Conhecimento Velomóvel

Prévia do material em texto

Velomobile Knowledge
Work in progress
Translation notes:
In the automobile world the steering rods are attached to the hub on the steering knuckle. I have used
this term in preference to “steering plate” – often in a velobobile the steering knuckle is a flat plate of
metal.
Some of the terms are the ones used by Google Translate / DeepL – they have either escaped my atten-
tion or I didn’t have a better idea. Please feel free to suggest better translations on the forum thread.
General Notes
What is a Velomobile?
A fully covered recumbent bicycle, typically with three wheels. The fairing provides weather protection and
improves aerodynamics significantly, but also provokes nicknames such as „egg on wheels“, „torpeedo“ or
„pill“.
How much does it cost?
The prices for new velomobiles usually range between 5000 and 10000 EUR. Of course they are cheaper
second hand but because of, not only low volume production, but also increasing demand, velomobiles are
relatively stable in value – often up to very high mileage.
Aerorider
Cabbike
El Loco
Leiba X-Stream
Leiba X-Stream
Milan GT
Milan SL
Quattrovelo+
Sunrider
WAW WAW
WAW
0 €
1,000 €
2,000 €
3,000 €
4,000 €
5,000 €
6,000 €
7,000 €
8,000 €
9,000 €
10,000 €
0 2 4 6 8 10 12 14 16 18 20
An
ge
bo
ts
pr
ei
s
Alter in Jahren
Quest
Mango
Alleweder
Go One
Strada
DF
sonstige
Fig. 1 : Second-hand prices for velomobiles in 2019 (without consideration of ori-
ginal price, configuration and condition). As one can see, the Quest, one of the
most produced velomobiles (see Fig. 6), has been offered accordingly frequently
and at various prices. In contrast, newer models like DF or Quatrevelo
(formerly: Quattrovelo) are still correspondingly expensive used.
https://cmoder.gitlab.io/velomobil-grundwissen/_images/GebrauchtPreise2019_optim.svg
https://cmoder.gitlab.io/velomobil-grundwissen/_images/GebrauchtPreise2019_optim.svg
https://cmoder.gitlab.io/velomobil-grundwissen/_images/velomobileworld_orderlist_medianage_de.svg
https://cmoder.gitlab.io/velomobil-grundwissen/_images/velomobileworld_orderlist_medianage_de.svg
Fig. 2 : Age of velomobiles produced so far, broken down by model. Since pro-
duction is constantly increasing, mainly due to additional new models, the me-
dian age is correspondingly low. (Status 09/2022; Milan only from MK6)
How much does one weigh?
Most velomobiles weigh between 20 and 30 kg. A few older models or those with an electric assist motor
are often well above that weight. There are also special racing designs weighing from about 16 kg. See Fig.
30 for velomobile models and their respective weight ranges.
Who makes such a thing?
There are a handful of manufacturers that make velomobiles, most are built by hand – most of these com-
panies are based in the Netherlands (three of them in Dronten), but there are also manufacturers in Aus-
tralia, Germany, Denmark, France and Switzerland. The principle area of distribution for velomobiles is
generally speaking the Netherlands, Benelux and Germany.
Who drives one?
Frequent drivers can be seen in the Graph of monthly driving performance. The velomobile is often used
for daily commuting.
The main areas of distribution of velomobiles are the Netherlands and Germany. Sales data of the Dutch
manufacturers (Velomobiel.nl, Intercitybike) are publicly available, see Fig. 3.
Fig. 3 : Countries to which Dutch velomobiles (i.e. Velomobiel.nl and
Intercitybike) were sold
Age distribution, according to a survey in the Velomobile Forum, see Fig. 4.
https://cmoder.gitlab.io/velomobil-grundwissen/_images/rijderslijst_countries_en.svg
https://cmoder.gitlab.io/velomobil-grundwissen/_images/rijderslijst_countries_en.svg
https://www.velomobilforum.de/forum/index.php?threads/velomobil-alter-hase-oder-junger-spund.47682/
https://cmoder.gitlab.io/velomobil-grundwissen/_images/age-histogram_en.svg
https://cmoder.gitlab.io/velomobil-grundwissen/_images/age-histogram_en.svg
Fig. 4 : Age distribution of velomobile riders from a survey in the Velomobil-Fo-
rum (as of: 2017–2019)
Where can I find more information?
In general, there is little literature and few websites. Most manufacturers have a website, but the informa-
tion there is often poor and/or outdated. But at least some dealers have very informative websites with tips
on the models they sell.
The main sources of information, however, are internet forums:
Velomobil-Forum (German)
BentRider Online (BROL, English)
Vélorizontal (French)
The German velomobile forum, with 4730 registered members (of which about 25% have specified a velo-
mobile model as of March 2021), is the leading forum, at least in Europe, where riders from other coun-
tries also participate. The wiki there is rather poorly maintained, most of the information is in the forum,
often buried deep in long discussion threads – you have to search for it.
More information can be found in the social media and Youtube channels, here Saukki’s channel
http://www.saukki.com/ is especially worth mentioning.
The scene is also well networked, there are regulars’ meetings in most of the larger German cities. The big
meeting place for the scene, however, is the annual Spezialradmesse SPEZI in Germersheim – practically
all manufacturers and dealers are present here, even if they are not exhibitors.
Where can I buy one?
Apart from at the manufacturers, there are also a few dealers spread across Europe (see Fig. 5). The best
way to see who sells which models is checking dealers listed on the manufacturer’s website.
Fig. 5 : Map of velomobile manufacturers and dealers (online interactive)
Who are the most important manufacturers and what are
their models called?
Manufacturers and models (alphabetical, incomplete):
Alligt: Alleweder (A1 to A6), Sunrider
Beyss Leichtfahrzeuge: Go-One Evo (K, Ks, R)
Cycles JV & Fenioux: Le Mans, Mulsanne
Drymer (Sinner): Hilgo, Mango (Plus, Sport, Tour)
Flevobike: Orca
InterCityBike: DF, DF XL
Katanga: WAW
Leiba: Leiba (Classic, Hybrid, Record, X-Stream, XXL)
Leitra: Leitra
Räderwerk: Milan (GT, SL), until MK5
Trisled: Aquila 2, Kestrel, Minihawk, Rotovelo, Tomahawk
Velomobiel.nl: Quatrevelo (formerly: Quattrovelo), Quest, Quest XS, Snoek, Snoek L, Strada
Velomobile World: Alpha 7, Alpha 9, M9, Milan (GT, SL) from MK6 on, Bülk
Velomobile in Hessen: Go-One Evo-R
Veloxiter: SR3
Others: After 7, Velayo
Interactive model comparison
Photo galleries:
https://cyclesjv.com/categorie-produit/velomobiles/
https://www.velomobilforum.de/
http://www.bentrideronline.com/
http://velorizontal.1fr1.net/forum
https://www.youtube.com/results?search_query=velomobile&sp=EgIQAg%253D%253D
http://www.saukki.com/
https://spezialradmesse.de/
https://cmoder.gitlab.io/velomobil-grundwissen/_images/map_velomobile-dealers.svg
https://cmoder.gitlab.io/velomobil-grundwissen/_images/map_velomobile-dealers.svg
https://www.google.com/maps/d/viewer?hl=de&mid=1Mr5RVj9MMaFSy7xnXUbZmODqEAZDI4n1
http://www.alligt.nl/
http://go-one.de/
https://cyclesjv.com/
https://www.drymer.nl/
https://www.flevobike.nl/
https://www.intercitybike.nl/
http://www.katanga.eu/
http://www.leiba.de/
http://leitra.dk/
https://velomobil.eu/
https://trisled.com.au/
http://www.velomobiel.nl/
https://www.velomobileworld.com/
http://velomobile-in-hessen.de/
https://veloxiter.de/
https://cmoder.gitlab.io/velomobil-grundwissen/vm-slider/vm-slider.html
https://cyclesjv.com/categorie-produit/velomobiles/
http://velomobiles.de/html/modellubersicht.html
Fig. 6 : Relative market shares of Dutch velomobiles (Velomobiel.nl and
Intercitybike as of: 02/2020)
Fig. 7 : Production figures from Velomobile World incl. earlier production (be-
fore 2020) in the Netherlands (as of November 2021). No earlier figures are
available for the Milans, therefore only from MK6.
Why are three manufacturers based in Dronten?
As you can see in Fig. 8, current velomobile production goes back almost entirely to the Alleweder. Today’s
manufacturers were either directly involved in the production of the Allewedera very constant speed – the gearing
there must be very finely graded – but on the other hand you cover a much wider speed range than with all
other bicycles, and you have a heavy vehicle which, uphill, must still be pedalled at a reasonable cadence
without going out of the saddle.
A fine gradation could also be achieved with a half-step gradation of the chainrings. However, it is very im-
practical to need two gear changes for each gear at high speeds, instead of simply shifting on a pinion.
Is a hub gear possible?
Rather not – hardly any IGH has a sufficiently large range of at least 500%. Only the Rohloff Speedhub
and the Pinion gearboxes are in that area. In addition, IGHs inherently have constant or symmetrical gear
changes, a flexible gradation is only possible with derailleur gears.
But what is possible and popular: combinations of derailleur and IGH. First, there are combined derailleur
and hub gears, here the hub gear extends the gear ratio range, and also enables gear changs to be made
quickly at traffic lights, for example, and the combination of both gearshifts to mitigate rough gear changes
through intermediate gears. Unfortunately, such a hub requires a two-sided swing arm. Second, there is
the Schlumpf Mountain Drive, although these only offer two gears and are less quick to shift with the heel
than with a gear lever, they offer an enormous gear jump, with which you can significantly expand the
range of the derailleur and do without the second chainring. Third, you can with a velomobiles install an
additional gearbox in the drive train, which can also be a hub gear. The disadvantage of all IGH systems is
the high weight.
Mountain bike or road bike cassette?
Neither nor. You cannot buy off-the-shelf an optimal cassette. Cassettes are no longer made from indivi-
dual sprockets, but are riveted together in groups. And for racing cyclists there are finely graduated casset-
tes with unfortunately too little gear range and for mountain bikers there is enough range, but incorrectly
spaced.
Therefore, some velomobile drivers facing this problem assemble the cassette themselves – either from a
mountain bike cassette, which you supplement with individual sprockets or entire sprocket groups from
other cassettes, or from special sets of individual sprockets. However, this rarely works without tinkering,
for example, spacers have to be adjusted or protruding parts have to be ground off. For optimal gear range,
it is often even necessary to drill out the rivets from riveted cassettes and rivet them back together with
new sprockets. Since the pinion wear on a velomobile is low thanks to little dirt, such a cassette will last for
many years.
Why can’t you change through all the gears?
Even a mountain bike derailleur with a long chain tensioner has a capacity of only 40 teeth, if the chain-
rings and sprockets have a larger tooth difference (i.e. teeth of the largest chainring + the largest sprocket
minus the teeth of the smallest chainring + the smallest sprocket), then the chain can no longer be tensio-
ned and sags. And an extended chain tensioner on the rear derailleur is rarely possible because the space
within the bodywork is too small. In practice, this means that only the largest sprockets can be used on the
small chainring. But you only lose “double” gears, and since these are mostly the small pinions, which are
ideally spaced anyway, it doesn’t matter.
Which chainring or cassette sizes work?
The smallest sprockets are freewheel body specific, smaller than 11 teeth does not fit on a normal Shimano
freewheel body. If you have a large rear wheel, you need a chainring with approx. 60 teeth in order to be
able to comfortably pedal up to approx. 60 km / h. And you want to be able to pedal uphill at 5 km/h, that
calls for a gear ratio of approx. 1:1. Because with well spaced cassettes the sprocket sizes only go up to ap-
prox. 40 teeth, and with a bolt circle of 130 mm the smallest chainring must have 38 teeth, there is much
to be said for compact cranksets, i.e. with 110 mm bolt circle, where you can also fit smaller chainrings.
The huge jump that occurs between the small and large chainring is customary, front derailleurs are
actually still changeable if they are carefully aligned (i.e. both the radial distance and the angle).
Cassette spacing?
Most of the time you drive on the flat, at speeds between 40 and 50 km/h. Accordingly, the sprockets
should be very finely spaced – a tooth difference is a much larger percentage difference with small sproc-
ket sizes than with large sprockets, and at high speeds and thus pedaling power, this also corresponds to a
big leap in performance that has to be mastered. You should ignore speeds higher than approx. 65 km/h.
They occur relatively often, but only downhill. No normal person can pedal at this speed for a long time on
the flat. And such speeds are usually over after a few seconds, you don’t need an extra gear for that, you
just let it roll a bit. Steep mountain climbs are not more common than steep descents – but it doesn’t take
seconds, but often many minutes to climb. A suitable gear is worth it here much sooner. So the bottom line
for the cassette is: the small sprockets finely spaced, towards the large sprockets always wider spacing.
Big or small chainring/sprocket?
At the same speed and cadence:
With a small chainring and small sprocket, the chain speed is low, but the chain tension high. This me-
ans: high losses on the traction run (with chain deflection), and a strong tensile load/deformation of
the drive.
With a large chainring and large sprocket, the chain tension is low and the chain speed is high. This
means: higher losses where there is little traction, for example on the empty strand.
In total, it is therefore advisable to drive on large chainrings – even if it feels as if the idle is less with smal-
ler chainrings. That’s true, but it’s the other way around under load.
Small chainring or large largest sprocket?
This is actually a matter of taste, the latter, however, has the attraction that you can then drive a lot with
the large chainring and rarely need the front derailleur. The efficiency is also somewhat higher there.
However, getting a well spaced cassette is more difficult if the largest sprocket is to be particularly large
(over 34 teeth).
Drivetrain
How big are the losses from chain idlers?
The following things happen on an idler:
The chain links are angled. The smaller the idler pulley, the stronger it needs to be – because the chain
links are distributed over fewer teeth.
The idler loads the bearing. If, for example, the chain is deflected by 90 °, it presses against the idler
pulley at a 45 ° angle.
The forces that occur are not negligible: with a deflection of, for example, 90 °, a force of sine(45°) = ap-
prox. 70% of the chain pull acting on the idler. Crank and chainring size can easily double the pedal force.
That can then correspond to a weight of 100 kg.
This is not so bad when the bearing is loaded: a ball bearing has very little friction, i.e. the losses are low
despite the high force. It is different with the force on the chain links. The deflection per chain link is much
less, the 90 ° deflection is distributed, for example, to 10 links on a large idler, and the force is
correspondingly low (here, for example, sine(9°) = 16% of the chain pull). But chain links are not ball bea-
rings, but plain bearings that have much higher friction – especially if they are also dirty.
Therefore, the most important measure is to keep the losses from idlers small: choose large idler pulleys!
One or two idlers?
Good question. Basically you can get the chain to the rear with an idler under the seat. But if it is also sup-
posed to be large so that the losses are low, it protrudes further down, and the chain runs obliquely at the
front and back. With two idlers you can lower the seat (i.e. lower cente of gravity ), but still have more
ground clearance, and the chain can come off the chainring more steeply so thatyou do not touch it with
your calves. In total, two idlers are slightly less efficient, but offer these other advantages.
Are ceramic bearings worth it?
Ball bearings made of ceramic are very wear-resistant and do not need any lubricant. Therefore, the stiff
ball bearing grease and seals can be dispensed with, which means that the bearings have lower losses.
However, even normal steel ball bearings have very low losses, in terms of magnitude, less than one watt
for all bearings in the drive train and wheels combined. That is why ceramic bearings can only save a frac-
tion of a watt at best – that is hardly measurable, and certainly not noticeable.
Are chain tubes inefficient?
A chain that grinds in a pipe naturally causes friction. And if the chain is oily and there is a lot of dirt stuck
to it, it also settles in the chain tube, the inside diameter becomes smaller and the chain grinds more often.
Wet dirt cannot dry and fall off as easily, but the wet dirt stays in the tubes forever.
But: in a velomobile, the chain is fairly clean because it has no direct contact with street dirt. Only the dirt
that the driver brings in, for example through dirty shoes, can land on the chain. And there a chain tube is
rather positive because it protects the chain from dirt. It is always damp in a velomobile and dirt collects at
the lowest point, i.e. happily below in the chain channel. It would not be a good thing if the chain were
permanently pulled through this damp dirt, but at least there tubes can help against the pollution.
The laying of the tubes is also important. Frictional force is the product of contact pressure and sliding
friction coefficient, where the chain is under tension, it does not follow the course of the tube, but is pres-
sed against the tube, the friction is correspondingly high. It is therefore important in the tension strand
that the chain does not follow the tube, but vice versa the tube follows the chain. If the chain does not
touch the tube under tension, there is no friction.
It is different in the empty strand. The chain sags there – in order to be frictionless, the chain tube would
have to follow the course of the sagging chain. But the contact pressure there is also low (namely only
approximately the weight of the chain), i.e. the friction is low. And in the Velomobile there is no space
anyway for the chain to sag freely – whether it is dragging in the chain tube or on the floor doesn’t make
much difference. In the first case, it is protected from dirt.
Alternative drive concepts?
Alternative drive concepts are discussed again and again, but so far none have been able to prevail over the
conventional combination of pedal crank + bicycle chain - mostly because their disadvantages outweigh
the advantages:
Belt Drive: A belt normally cannot be reversed, making it impossible to route backwards under the
seat. In addition, it is not compatible with a derailleur (which is superior to the vast majority of gear-
boxes because of its range of gear ratios), cannot be opened (which prohibits all closed bushings), and
the efficiency is somewhat lower.
Linear drive: A pedal drive without cranks would have geometric advantages, because the front of the
velomobile does not have to accommodate the extensive pedal circuit - especially for riders with long
legs and correspondingly long cranks and large feet, the front could be flatter and the angle of depar-
ture steeper. But the ergonomics are worse because the legs don’t describe a circular movement, but
have to come to a standstill at the dead points. This prevents high cadences.
Cardan shaft: A high torque must be transmitted on a bicycle. While a chain is only subjected to tensile
loads, a cardan shaft has to withstand torsional forces - and in order to be sufficiently stiff, it has to be
very thick and solid. In addition, the two bevel gears at the ends cause additional losses.
Electric drive: With a combination of pedal generator and electric motor, you can design the power
transmission geometrics completely freely and with the appropriate electronics you can even do
without a mechanical gear shift. However, the double conversion between mechanical and electrical
power generates high losses.
Hand crank drive: The leg muscles are significantly stronger than the arm muscles. Therefore, a drive
with only the arms does not make much sense. If, on the other hand, you use both arms and legs for
propulsion, you have significantly more power at your disposal. However, pure muscle power is only
decisive for short sprints, over time, the limiting factor is the supply of oxygen and nutrients to the
muscles – i.e. circulation, lung function and digestion. Therefore, a hand crank drive only adds a lot of
additional mechanics and thus weight, but that does not make it faster.
Why a stiff drivetrain?
Whenever you pedal hard, a stiff velomobile is important, because then the pedaling force ends up on the
road instead of in the deformation of the vehicle. This deformation is of course elastic, i.e. as if you were
tensioning a spring. However, such a deformation naturally has hysteresis, that means you don’t get back
all the energy you put into it.
But that’s not even the main problem: when you pedal on a stiff bike, the pedaling energy is immediately
converted into speed – if you stop pedaling afterwards, the bike is faster and the pressure on the pedals is
in the correct path. If, on the other hand, the frame is deformed by the pedaling energy, it is then under
tension – i.e. it pulls on the chain and accelerates the bike, but it also presses on the pedals and thus on the
muscles. But they don’t like that at all. For example, when you lift a weight, the muscles do lifting work,
but if you keep a weight at the same height, physically no work is done, but it still feels tiring, and the mus-
cles are consuming nutrients. Muscles therefore consume energy when they only have to exert a static
counterforce – a screw in the ceiling, on the other hand, can carry the weight of a lamp for centuries
without tiring. And that is why this counteraction against an elastically deformed drive train costs force
that is then missing for acceleration..
What needs to be stiff?
The forces that occur are primarily the chain pull and the pressure of the driver’s back in the seat shell.
Everything that goes with it has to be rigid:
The bottom bracket is attached to the bottom bracket mast.
This is above the steering bridge with the front wheel connected to the wheel wells. There are many
curved surfaces and relatively thick material here, which means that there is enough rigidity.
The chain movement pulls the idlers up, the front one is therefore usually connected to the stiff stee-
ring bridge.
The chain idler also wants to pull the vehicle floor between the two idlers together like a bowstring.
That is why in many velomobiles the chain tunnel also has a static function, because it serves as a U-
profile that stiffens the vehicle floor in the longitudinal direction.
The chain pull goes on to the rear wheel, whose swing arm must be correspondingly rigid and also
must be well supported by the bodywork.
Also the seat must be securely attached. For this reason, for example, some seats are bolted to the
front of the front wheel wells and are supported at the rear against the rear wheel arch, which often
holds the swing arm bearing in the front and is accordingly strong.
The body between the rear swing arm bearing and front wheel housings must also be sufficiently rigid.
But this is basically the case because it is a tube with a large diameter. However, openings that are too
large are disadvantageous, the velomobiles, which have huge entry openings, are correspondingly
massive and heavy. (There were also convertible cars, for example, which had to be reinforced in com-
parison to their closed coupé counterparts, because otherwise they would not have been stiff enough.)
The rest is not so important and can be made thin-walled accordingly.
It also depends on thedirection of the deformation: It is bad if the deformation creates a counter-pressure
to leg strength - muscles are strained without the power going into the drive. On the other hand, it is not so
bad if slight torsions occur in the bottom bracket mast - the force component in the pedaling direction is
only small. Therefore, the goal is not rigidity at any price, but a good compromise between lightweight
construction and rigidity in the pedaling direction.
Brakes
What are the requirements for a velomobile brake?
In any case, not particularly high braking forces. Firstly, the Velomobile has two front wheels that can be
easily braked, secondly, the front wheels are small, i.e. the lever between the radius of the brakes and the
radius of the wheels is smaller than with large wheels, and thirdly, you drive more smoothly, not downhill
like on a mountain bike, on a surface which has surprises in store. In practice, the limiting factor is the
tyres, a well adjusted brake can usually be blocked.
To do this, the brake must be able to withstand high heat output (see Fig. 15). Firstly, there is little drag on
the Velomobile that slows it, while a mountain bike hardly ever sees speeds faster than 60 km/h, a velomo-
bile easily reaches over 100 km/h. Second, with the Velomobile, the usual speeds are higher, with the same
gradient, a higher speed means that more altitude energy has to be braked away per time. And thirdly, a
velomobile is heavier and the brakes in the wheel wells are less well cooled.
So the problem is not short braking maneuvers, but long descents. Larger drum brakes help here, simply
because they are larger their heat disapation capacity is higher – there is more material that can be heated,
and the surface area of the hub shell is also slightly larger.
And what happens if the brakes are too hot? First, they fade i.e. the braking effect decreases noticeably. Se-
cond, the hub shell can expand so far that the spokes lose their tension and get loose when the wheel rolls,
and soon break through material fatigue due to the alternating load.
Fig. 15 : Braking power needed to maintain speed on various gradients: the so-
lid curves show a velomobile, the dashed ones a racing bike. While on the latter,
drag increases so much that, at higher speeds, the necessary braking power de-
creases again, and on a gradient below 5%, you don’t have to brake at all to keep
from going over 50 km/h, on the velomobile, this maximum power required is
much higher and at much higher speeds. While a road bike brake does not have
to withstand more than 500 W on a 10% incline, with a velomobile it is almost
twice as much at the same speed and at its highest at three times the speed, al-
most four times as much is needed.
How can I cool the brakes or make them less hot?
One way is to direct more of the airstream onto the brakes. This was done, for example, with the Velomo-
bile that Marcel Graber used to do the Trans America Bike Race 2018 – he used wheel well covers
(“pants”) and, correspondingly, front wheels without a wheel disc, and air channels were cut into the wheel
well linings pointing towards the hub.
Another option is water cooling, which was implemented by Patrick Flé (Velomobilize): with a plastic bot-
tle and a hose, water is sprayed into the brake drum, the water evaporates immediately because of the heat
and the vaporization means a very high amount of energy can be dissipated. The brakes can withstand this
temperature shock mechanically.
Then there were also experiments with continuous braking. Firstly, with an additional rear brake, owever,
this has the disadvantage that the rear wheel locks slightly and then tends to break out. Another method is
to use braking parachutes, it has proven useful to use two parachutes, each with a diameter of approx. 40
cm. However, this is only of limited practical use because firstly the parachutes have to be ejected
manually at the start of the descent, secondly you have to stop at the end of the descent to repack them,
and thirdly the parachutes dancing around are probably not recommended in heavy traffic.
The most practical methods are, however cooling fins and cooling towers of brakes sold by Ginkgo bike
parts. These are milled into the brake drums or glued to them. This increases the surface area of the brake
drums and air can cool them more effectively.
And last but not least, you can make the brakes heat less with your driving style: the worst thing is to drive
downhill at high speed and brake constantly. Intermittent braking means that higher top speeds are achie-
ved so braking drag is higher when the brakes are applied, and then higher temperatures are reached when
braking, which makes heat conduction to the air and heat radiation more effective. During the following
pause, the brakes can cool down more than if the brakes were applied permanently.
Why does a Velomobile have drum brakes?
Because no other brakes are suitable.
It has no disc brakes because they are attached next to the wheel. Exactly where there is the least space,
because the wheel well is insufficient, and a brake would also have to be housed next to the driver’s thighs.
That would only be possible if the velomobile were made wider. A brake disc itself is not particularly wide,
but additional space is required when turning, which must be available in the wheel well. There are velo-
mobiles with disc brakes, they do not have normal spoked wheels, but disc wheels – these are concave in
https://cmoder.gitlab.io/velomobil-grundwissen/_images/speed_vs_brakepower_downhill_en.svg
https://cmoder.gitlab.io/velomobil-grundwissen/_images/speed_vs_brakepower_downhill_en.svg
shape so that the brake disc can be accommodated further inside the wheel. However, these wheels have
other disadvantages, such as higher weight, and cannot be centeed. Another argument against disc brakes
is the poorer cooling in the wheel well, the brake disc and brake pad are relatively small and therefore heat
up quickly. Since the wheels are in wheel wells, the rainwater does not simply run off, but is repeatedly th-
rown by the wheel into the wheel arch and drips down in there, onto the brakes together with street dirt.
An unprotected disc brake would therefore wear out quickly in a wheel well.
There are no rim brakes because that would be difficult to achieve with front wheels suspended on one
side, cantilever bosses on both sides are fundamentally not possible, and even a side-pull brake does not fit
easily into the wheel well if the wheel must also be able to turn. In addition, a rim brake protrudes
outwards, which would be aerodynamically very unfavorable. A rim brake also heats the rim, this would
quickly overheat the rim when going downhill due to the high driving speeds and small wheel sizes.
So there are only drum brakes.
Why no brake on the rear wheel?
For two reasons:
The rear wheel is relatively far away from the centre of gravity – while the driver sits almost between
the front wheels, he sits quite a way from the rear wheel. Therefore, there is little weight on the rear
wheel – you can tell by how easily it spins on slippery roads. In addition, the braking deceleration en-
sures dynamic shifting of the wheel load to the front, which further relieves the load on the rear wheel.
You could only transfer small braking forces with the rear wheel before it slips.
A slipping rear wheel is dangerous because it slides equally well in all directions – while a rolling wheel
moves much easier in the direction of roll than across it. That means a slipping wheel doesn’t have op-
posing lateral grip anymore and lateral forces accordingly, which can be very dangerous (see: Why is it
dangerous when the rear wheel slides? ).
What is this about shims for drum brakes?
The Sturmey Archer drum brakes consist of two brake pads, which are attached to a common bearing on
one side and are pressed apart by a rotating cam on the other side. With new brake pads, this cam only has
to rotate a little until the brake pads touchthe brake drum. Because of the small actuation angle, the rota-
ting cam mostly pushes the pads apart and hardly ever moves sideways.
It is different with worn brake pads. The braking force remains approximately the same since the brake ca-
ble has been adjusted accordingly. However, the cam now has to rotate much more and also moves
sideways quite a bit. When the brake lever is released, it is reset by means of a spring that pulls the brake
pads back together, this spring no longer manages to press the cam hard enough so that it also slides along
the side of the brake pad holder – the brake no longer resets to off and locks up.
As a remedy, you can increase the distance between the brake pads and cams so that the worn thickness of
the brake pad is compensated for. This is achieved by using a thin metal shim under the sliding shoes on
which the brake pad holders slide on the cam (shim thickness e.g. 0.8 mm). Then the cam no longer has to
turn so far and accordingly moves less sideways. This is not critical for the brake pads, their thickness is
ample even if the cam causes problems. So you can realign the brakes several times, and even then the pro-
blem is that the shoe is not holding, but there is still plenty enough brake pad.
On this occasion you should also lubricate the cam and the sliding shoes, it is best to use copper paste be-
cause it is heat-resistant.
Why not apply the parking brake after a long downhill
ride?
On long descents, a brake gets very hot – including the housing, which is made of aluminium. This beco-
mes soft due to the heat, and if the wheel no longer turns but the brake is permanently applied, it can de-
form slightly. This is not immediately dangerous – but the brake is then out of round and can no longer be
adjusted so well. Therefore, the parking brake should only be applied after the brake has cooled down.
Electrical
Headlights: which ones? Where?
There is never enough light on a velomobile. First, you are often traveling at high speed – possibly up cycle
paths that are not made for this and have no painted lines or reflectors down the sides – secondly, you sit
low and therefore have a poor view of the street and are often dazzled by car headlights (especially when
the left-hand cycle path is lower than the street), and thirdly, the headlights are often mounted quite low –
and bicycle headlights are usually designed for a significantly higher mounting position.
While bright lighting is sufficient on a dry road, you will come up against limits on wet roads and in dazz-
ling oncoming traffic with normal bicycle lights. Here at least it helps to mount the headlight as high as
possible. But being on the hood is often counterproductive because you blind yourself. Therefore, an inter-
nal headlight is recommended, but as high as possible, without ruining the aerodynamics.
Turn signals: which ones? Where?
Since you can’t practically make hand signals, turn signals are highly recommended. These should be far
enough apart that it is clearly visible in the dark which side is flashing. Since turn signals are only used
very briefly, the power consumption is irrelevant – LEDs, as bright as possible (e.g. 3 W, 700 mA, with lar-
gest possible beam angle), and in the front for aerodynamic reasons inserted into the bodywork. Suitable
flashing relays are available for motorcycles.
Electronics inside are weatherproof and protected right?
Yes and no. Of course, wind and weather do not hit the inside of the velomobile. However, you sweat a lot
more, and in cold weather the air you breathe condenses on the cold bodywork surfaces. The velomobile
has a climate like that of a tropical stalactite cave, and the electronics have to be able to withstand this.
Anything that is not properly sealed or protected corrodes quickly.
Dynamo yes or no?
A bicycle which is more than a fair weather bike should have a good lighting system powered by a hub
dynamo. This is a bit more difficult with velomobiles: on the one hand these are everyday bikes with high
mileage – on the other hand there is no good dynamo solution yet. There are high quality hub dynamos for
front wheel hubs suspended on one side but these are for trikes that have disc brakes. Velomobiles usually
have drum brakes, i.e. the space in the hub is used for those.
It also is difficult on the rear wheel, there are dynamos for a cassette rear hub, however, they have rather
poor performance. And they are only available as double-sided hubs. Velomobile drivers with one-sided
swing arms abstain!
Then there would also be cross-country dynamos. However, you can only run these on the rim, since the
thin flanks of faster tyres would not be able to withstand the stress of a dynamo roller. In addition, you
would have to attach the dynamo somewhere in the wheel arch, where there is a lot of water and dirt when
it rains – so the dynamo doesn’t have an easy life and would probably slip easily.
And last but not least there is a combination of hub dynamo and drum brake from Sturmey Archer. Howe-
ver, this is not really convincing, because firstly, the efficiency is not great, secondly, the permanent mag-
nets will not tolerate the heat of the brakes for a long time (Curie temperature!), and thirdly, the disman-
tling of the wheel is nowhere near as easy, because not only one screw has to be loosened, but also the wi-
res have to be removed.
Finally, there is also the problem that a velomobile uses a relatively large amount of electricity. For a hea-
dlight, the typical 3 W of a dynamo is absolutely the bottom limit, it can sometimes be triple that. At least
one buffer battery is required. And that’s why most velomobile drivers stick to pure battery lighting.
Which voltage for the vehicle electrical system?
It used to be easy, since the dynamo always delivered 6 V at moderate driving speed, with which the incan-
descent light bulb shone passably, and at high speeds the dynamo made sure that not too much current
flowed despite possibly higher voltages. With a light bulb you only have to apply a voltage, the resistance of
the filament increases with the temperature, so that the current can only increase until it glows brightly.
It is different with today’s on-board electrical systems. A battery can deliver almost any current, and even a
LED no longer has this negative feedback that limits the current, rather the opposite. This is why electro-
nics are needed to regulate current and voltage. Many devices have such a thing built-in and tolerate a
wide voltage range, for example from 6 to 16 V. And naked LEDs do not really care about the voltage
anyway, it has to reach a certain minimum value, but otherwise the current has to be limited, which is so-
called constant current source (CCS).
Accordingly, some people prefer 12v battery systems because they can easily install motorcycle parts.
Others use 6v to install bicycle components. As long as all devices can cope with the voltage, and all LEDs
are connected to constant current sources and, for example, a USB cable is connected to a 5 V voltage con-
verter, the voltage of the vehicle electrical system does not matter much.
How to treat a lithium-ion battery?
Do not overcharge: When the final charge voltage is reached, the charging process must be stopped.
Do not undercharge: When the minimum voltage is reached, no more current may be drawn.
The drawn current must not be too high (rarely a problem in the velomobile).
The charging current must not be too high.
The temperature must not be too high.
These things are checked by any standard charger when charging, the charging current is kept constant
and, with increasing battery voltage, the charging voltage is increased until the final charging voltage is re-
ached. Small BMS boards are usually integrated in the removable battery (Battery Mnagement System),
which switches off the battery if the current is exceeded or the voltage limits are exceeded or undershot.
In addition, batteries with cells connected in series also need balancing, in whichall cells are fully charged
and evenly if they have previously discharged unevenly. However, this is more relevant for high currents,
for example for electric drive motors, with usual use as light batteries, one can usually do without
balancing.
To be sure that the battery lasts as long as possible, firstly the charging current should be kept low, and
secondly the battery should not be completely drained or fully charged, ideally it is not discharged below
30% and not above 80% to 90% (depending on the source).
Where do I attach the speedometer / GPS / Navigation?
Where you can see it well. If the display is large, this can be on the wheel arch or directly in front of the
eyes on the front edge of the cockpit. With a tiller handlebar, you can also attach the navigation system
there.
GPS reception under carbon?
It is well known, carbon fibers are electrically conductive – and will shield from electromagnetic waves
accordingly. Experience has shown that the GPS reception inside a velomobile works quite well, at least
with modern GPS receivers. But the signal strength decreases noticeably when the hood is put on, and if
there is also rainy weather with thick layers of cloud, the devices find it difficult to find the exact position.
However, signal is usually sufficient for navigation – at least when looking on the display and with a good
map (see Fig. 16). However when using voice navigation, the exact position is more important; if the an-
nouncement is delayed due to poor reception, one can easily miss a turn.
To improve GPS reception, some drivers use GPS repeaters. Alternatively, on some velomobile models,
you can purchase a service hatch cover or hood made of fiberglass or basalt fibres, these are not electrically
conductive and therefore permeable to GPS signals.
Fig. 16 : GPS recordings made from inside the wheel arch (device: Wahoo
Elemnt). On both maps you can see 10 rides each, which were made directly one
after the other – on the left without a hood, on the right with a hood.
Not only the GPS position, but also the measurement of altitude can be a problem in the velomobile. GPS
altitude measurement is notoriously inaccurate because the visible satellites are all up, i.e. in the vertical
direction the signal propagation times hardly differ – accordingly, with poor GPS reception, GPS altitude
measurement becomes even worse. However, most GPS receivers use a barometric altitude measurement,
i.e. the altitude is determined from the air pressure and the GPS altitude is only used to detect air pressure
variations (see Fig. 17). So altitude measurement should not be a problem even inside a carbon body. But
as you can see in Fig. 17, the GPS altitude deviates from the true altitude at higher speed – there is
obviously a negative pressure building up there which makes the altitude look too high.
Fig. 17 : Altitude profiles from 42 rides, recorded with GPS (device: Wahoo
Elemnt) on the wheel arch. While the shapes of the altitude profiles are very simi-
lar there are big differences in the absolute heights.
https://cmoder.gitlab.io/velomobil-grundwissen/_images/GPS_100tracks_2maps.svg
https://cmoder.gitlab.io/velomobil-grundwissen/_images/GPS_100tracks_2maps.svg
https://cmoder.gitlab.io/velomobil-grundwissen/_images/GPS_42elevation.svg
https://cmoder.gitlab.io/velomobil-grundwissen/_images/GPS_42elevation.svg
Fig. 18 : Comparison of the altitude measurement of a GPS with barometric me-
asurement (Wahoo Elemnt) at different speeds (velomobile: DF, without bonnet,
GPS inside on the wheel well). Uphill the values agree, downhill at over 30 km/h
there are significant deviations. The higher the speed, the greater the measured
height, there is therefore a vacuum in the vehicle.
Which navigation system?
In a velomobile, a navigation device or GPS with a map display is very useful, because it allows you to drive
with much more foresight and thus save energy in unknown areas, after getting lost it takes a lot of time
and effort to regain speed after braking, especially in a velomobile.
However, there are hardly any independent navigation devices that are suitable for bicycles and especially
for velomobiles. Car sat navs are completely unsuitable because they prefer highways and main roads –
where bicycles are either prohibited or one feels very uncomfortable due to large speed differences. Bicycle
sat navs often prefer cycle paths and dirt roads, on which efficient travel is impossible and where confu-
sion or getting lost at high speeds is dangerous.
Real-time navigation therefore only works effectively on a smartphone, where the route calculation is car-
ried out by BRouter and any supported app can be used to display it (e.g. OsmAnd, Locus Map).
Otherwise you can create a track before the trip and either follow the line on the map, or, if the track is
provided with navigation instructions, follow these via audio announcements.
In addition to this functionality, there are the following things to consider with the hardware:
Power consumption (higher with a large display)
Protection (against splashing water): a velomobile is like a stalactite cave, electronics have to withs-
tand humidity
Usability, even when damp, beware of bad touchscreens
Motor yes or no?
A velomobile drives fairly quickly on the flat, but is slow uphill and also accelerates slowly. The average
speed is the average over time, i.e. slow sections are more important – it is more useful to be faster in slow
sections than to increase top speed. Therefore, an engine is useful for travel time if there are many slow
sections that can be shortened with it. Because you only need the engine on these few sections and not
otherwise, the battery can be comparatively small.
However, an engine does not help much in stop-and-go traffic, there are many exhausting acceleration
processes, but because of the braking in between, you will not be able to reach the speed of the open road,
even with an engine. Here, an engine relieves the driver but does not make her/him much faster.
Also the amount of elevation gain is not as meaningful. On short climbs you can get some momentum be-
forehand and still have enough remaining speed at the top to be faster overall with a much lighter bike, but
this only works up to about 10 meters of altitude at a time (see Fig. 32). You only go slower on long climbs
(see: Can I ride in the mountains?), and only here would an engine reduce the travel time noticeably.
And then, of course, there are the legal regulations. In Germany (and the rest of the EU), a pedelec motor
is allowed to assist up to a maximum of 25 km/h, on a straight stretch, it would only be in use for a few se-
conds in a velomobile, and is therefore simply not worthwhile. Uphill, of course, it’s different. Faster mo-
tors can not be retrofitted, see: Is it possible to fit a 45 km/h motor?
Which engine?
There are basically two types here bottom bracket motor and hub motor, direct drive or geared.
A direct drive hub motor has the advantage that it can also brake, you can feed the braking power back
into the battery (recuperation), and thus recover up to 2/3 of the braking energy. This is particularly inte-
resting in very hilly terrain, where you have to brake a lot, so you can protect the brakes and then use the
energy for short accelerations. The problem is that these direct drive wheel hub motors have no gears, So
they can either drive fast or be powerful, but not both. And the steeper the slope, the more power the en-
gine would have to deliver, but its power increases with engine speed. So the slower it goes uphill, the
lower the efficiency – the engine overheats quickly. Direct drive wheel hub motors are therefore unsuitable
for long gradients. They are also quite heavy.
https://cmoder.gitlab.io/velomobil-grundwissen/_images/testride_chung_distance_speed_elevations_en.svg
https://cmoder.gitlab.io/velomobil-grundwissen/_images/testride_chung_distance_speed_elevations_en.svg
Geared hub motors are lighter (2.3 to 3 kg) and more adaptedto a velonobile, being geared they develop
more torque and climb quite well with relatively little power. In the correct gear – the driver still has to
participate – long gradients up to 13-14% are climbed with ease. Most popular geared hub motors fit stan-
dard dropout width and accept 10 speed cassettes. Some common motors (Mxus) are freewheel motors
and limited to 8 speed freewheels to stay within 138 mm dropout width.
Bottom bracket motors, on the other hand, are mounted beyond freewheels and gears. Therefore, they can
be small and light, because they can work at high speed and use the bicycles gears, i.e. always work in the
optimal speed range regardless of the gradient without overheating. No recuperation is possible. If you
have long or very steep inclines, a bottom bracket motor is the better choice.
How should the gearing of a bottom bracket motor be
chosen?
Electric motors are most efficient at a certain speed. The gearing should be chosen so that it is at comforta-
ble pedaling cadence in the assistance range (i.e. pedelec up to 25 km / h). If the motor then also ensures
that the driver accelerates as quickly as possible beyond the support area, the power consumption is the
lowest – either the driver (mostly) pedals himself or the engine works in its most efficient speed range.
Is it possible to fit a 45 km/h motor?
In Germany and the rest of the EU this is not allowed – because according to StVZO § 63a Abs. 2 a bicycle
may have an auxiliary drive with assistance up to a maximum of 25 km/h. There are indeed 2 and 3 whee-
lers (S-pedelecs) and even velomobiles that have a motor that assists up to 45 km/h, however, these are
legally no longer bicycles, but are considered light electric vehicles – three-wheeled velomobiles, for exam-
ple, belong to EU vehicle class L2e. This has the following consequences:
Registration: the vehicle must have undergone a registration procedure and carry a number plate.
Driving licence obligatory: A driving licence of class AM is required.
Compulsory insurance: You need motor vehicle insurance.
Compulsory motorcycle helmet
Use on cycle paths is prohibited
Restricted to approved components: One may not install arbitrary bicycle components, but must stick
to type approved equipment.
Prohibition of certain types of construction, e.g. a glass dome roof.
One does not necessarily have to pedal, but can also ride purely electrically.
This means: You cannot simply equip an existing velomobile with a 45 km/h motor, but you must buy a
specially approved 45 km/h velomobile. Since the approval process is expensive and time-consuming,
there are only a few 45 km/h velomobiles available. And they are very different from sporty velomobiles –
the weight is much higher, the tyres have higher rolling resistance, and riding without a motor is possible,
but much slower than with non-motorised velomobiles. 45 km/h velomobiles are therefore a completely
different type of vehicle with a somewhat different type of use.
http://www.gesetze-im-internet.de/stvzo_2012/__63a.html
Aerodynamics
Why are velomobiles fast?
Because of their low drag. As can be seen in Fig. 19, bicycles usually have rather poor aerodynamics, their
drag coefficient (cW) is much higher than that of a car. The only reason why drag is not higher is because
the cross-sectional area (A) is much smaller than that of a car. In contrast, the cross-sectional area of a ve-
lomobile is not necessarily smaller than that of a racing or recumbent bike, but the aerodynamics are much
better than even an average car, so that the effective cross-sectional area ( ) is much smaller – for a
very good velomobile only about 0.03 m², which corresponds to the area of a DIN-A5 sheet of paper.
Fig. 19 : Comparison of the drag coefficient ( ), the cross-sectional area ( )
and the effective cross-sectional area ( ) between different bicycles, velo-
mobiles and cars As you can see, racing bikes and recumbents are faster than
Dutch bikes mainly because their cross-sectional area is smaller, the
aerodynamics are not very good either. On the other hand, the cross-sectional
area of a velomobile is similar, but the aerodynamics are much better.
What is drag?
Air resistance is basically very complicated, the following effects occur there:
Pressure resistance: The air is slowed down (from the vehicle’s point of view) and accumulates, i.e. ki-
netic energy is converted into pressure energy (and to a small extent into heat), but this cannot be
completely converted back into kinetic energy from the outflowing air because of frictional resistance
and is therefore lost.
Frictional resistance: Friction occurs between the stationary surface and the flowing air, the rougher
the surface, the more a boundary layer forms. The air directly contacting the surface adheres to it, its
velocity is zero. With increasing distance from the surface, the speed of the air increases until it rea-
ches a maximum outside the boundary layer, in the free air. Here the boundary layer thickness varies
from 0 at the front to several cm at the rear of the velomobile.
Interference resistance: Interaction between the flow around neighbouring bodies, e.g. wheel and
body.
Induced drag: Different pressures lead to an equalising flow due to their differential force, e.g. in an
aeroplane the lift of the wings results from the differential force between a positive pressure on the un-
derside and a negative pressure on the upper side, but the resulting equalising flow from the underside
to the upper side causes turbulence at the wing ends.
Depending on the shape of the body, these effects vary in strength. With a blunt body, the pressure resis-
tance dominates, but the more streamlined a body is, the lower the pressure resistance becomes, i.e. the
proportion of frictional resistance becomes greater and thus dominant. A velomobile has a streamlined ba-
sic shape, but air accumulates at the wheel wells, mirrors and lid, so that both pressure and frictional resis-
tance play a role. In a highly optimised record vehicle it is different, there the frictional resistance domina-
tes, for example, in the record vehicle Aerovelo Eta the sponsor stickers were gathered at the very back of
the fuselage in order to make the surface in the area in front of it as smooth as possible and thus low-fric-
tion (largely laminar).
In any case, drag leads to a gradient in the flow velocity air, and this can lead to turbulence.
What is the cW value?
Air resistance is caused by a combination of different effects (see: What is drag?), in which not only
the shape of the body plays a role, but also, among other things, its surface properties and size as well
as the density and viscosity of the medium. A turbulent flow is too complex to be calculated
analytically, but for similar conditions one can describe the influences approximately by parameters.
One of these parameters is the value (drag coefficient), which describes the amount of drag indepen-
dent of velocity, size of the body and density of the medium. It includes both the shape of the body and (to
a lesser extent) its surface characteristics and describes the magnitude of all effects that enter into the drag
in a single number. Thus, it is a completely non-physical value to which no single law or measurement cor-
responds. But it can be used to calculate air resistance with sufficient accuracy by multiplying it by the
density of the medium, the reference area and the square of the velocity.
Strictly speaking, the value is not even a constant, because it changes with the flow behaviour of the
medium. This is described by another key figure, the Reynolds number. Roughly speaking, it expresses the
relationship between inertia and internal friction: If the number is low, the medium moves as a unit, a
high viscosity causes a strong internal friction, which hinders relative movements within the medium – it
is a laminar flow. With a high Reynolds number, on the other hand, the viscosity or internal friction is
cW × A
cW A
cW × A
cWcW
https://cmoder.gitlab.io/velomobil-grundwissen/_images/comparison_cW-A-cWA_en.svg
https://cmoder.gitlab.io/velomobil-grundwissen/_images/comparison_cW-A-cWA_en.svg
proportionally low and the inertia is high, so that parts of the medium can move more independently of
each other and, if they are deflected at an edge, for example, they do so – turbulence occurs. The Reynolds
number is not only material-specific, but also increases with velocity – while a slow medium is still lami-
nar, the inertial forces increase at higher velocities, so that turbulence occurs. In addition, turbulence also
needs a certain distance to develop – which is why the same flow can still be laminar with a small body,
but already turbulent with a large one, and why you need a correspondingly higher flow velocity in a wind
tunnel with scaled-down models in order to produce the same Reynolds number and thus the same flow
behaviour.
For the value, this means that it decreases relatively strongly with velocity in a laminar flow, whereas it
decreases only slightly with velocity in a turbulent flow. In the case of vehicles, at least at higher speeds
where air resistance is no longer negligible, one is in the turbulent range and can therefore assume a cons-
tant value around the reference speed. However, this means that one has to know the reference speed
at which the value is measured – for cars this is 140 km/h, for velomobiles one would have to choose a
practical reference speed of e.g. 50 km/h accordingly in order to be able to compare the aerodynamics.
How to achieve low Air resistance (drag)?
Ultimately, by releasing as little kinetic energy into the air as possible. I.e. the air should be slowly pushed
aside and slowly return to its original position. Any acceleration energy that is released into the air is lost
for the drivetrain.
A single air molecule cannot be accelerated linearly very much because the neighboring air molecules are
in the way, they should also be accelerated. You can squeeze them a bit, but that creates back pressure. Li-
near acceleration therefore quickly reaches its limits. The situation is completely different with rotations:
an air molecule can rotate almost anywhere on the spot without being obstructed by the neighboring air.
You can lose a lot of energy by rotating air – so it is essential to avoid turbulence.
Why is a teardrop shape usually quite efficient?
In short: because it is easier to push air part without a vortex than to let it flow back together again without
a vortex. The former can therefore happen quickly, the latter takes more time and therefore a longer
journey.
But of course there are exceptions. For example, the Kamm tail, which corresponds to a sharply cut tear-
drop shape. This will interupt the flow suddenly, instead of it being sucked back in. Aerodynamically, this
is not quite as good, but it saves you a long stern, with its extra weight and its larger wind attack surface.
Why no wing profile?
The profile of an airfoil is considered the perfect example of an aerodynamically good shape. But why does
it have this shape? First, a wing must accelerate air downwards, and for this it must have an angle of attack
relative to the flow angle. Second, on the other hand, where there is negative pressure, they do not break
the current, that is why this side is not straight, but curved so that the air is slowly drawn around the curve
instead of abruptly tearing off at the front edge. A velomobile, on the other hand, has no angle of attack (if
the wind results from the front), it shouldn’t accelerate the air if possible. The same thing, however, is that
a stall should be prevented – hence the even, flowing shape without sharp kinks.
Why is the front blunt instead of being pointed?
Usually one associates little flow resistance with slim, pointed shapes. But the front of most velomobiles is
round. It is true that the incoming air has to be slowly moved to the side instead of suddenly hitting a blunt
surface. But this is not the case: the air builds up in front of the velomobile during the journey, and this
“mound of air” acts like an elongated snout that deflects the incoming air to the side beforehand. Such a
mound of air would not build up on a point, i.e. the air would suddenly hit the body, nothing would be
gained.
Why are open wheel wells sharp at the front and round at
the back?
At the front of the wheel well, the edge is as sharp as possible so that the air flow does not follow the body,
but tears as much as possible and flows back past the wheel. Of course, this is only possible to a certain ex-
tent. At the rear, on the other hand, the part of the flow that has penetrated further into the wheel well
should not hit and swirl on the rear of the wheel well, but should be gently pressed outwards so that the air
flow is again parallel to the body.
What are pants?
These are fairings that are used on velomobiles with open wheel wells and are attached outside over the
wheels to improve aerodynamics (see Fig. 20). As a result, you have the good aerodynamics of a velomo-
bile with closed wheel wells – but a slightly wider track (i.e. better cornering stability) and the flexibility to
convert to open wheel wells again. Pants can be removed if something has to be done on the tyres or whe-
els, but they also make overall width increase significantly. The latter can be mitigated with a special whe-
elset with the rim spoked further inwards.
Pants were first made for the DF design, but fit most velomobiles with open wheel wells. They are quite
light and flexible and are simply stuck on with adhesive tape.
cW
cW
cW
https://cmoder.gitlab.io/velomobil-grundwissen/_images/Hosen_Alpha7_DF_P1066995.jpg
https://cmoder.gitlab.io/velomobil-grundwissen/_images/Hosen_Alpha7_DF_P1066995.jpg
Fig. 20 : Two velomobiles with open wheel wells, in front an Alpha 7 with pants
on the front wheels, behind it a DF without pants.
Why is the underbody next to the foot bumps curved, not
flat?
Foot bumps protrude outwards and displace the incoming air. However, this cannot escape arbitrarily, be-
cause the road is a few centimeters below. So it can only escape to the side. If the vehicle floor next to the
foot bumps were flat, the flow cross-section for the air would be reduced at the level of the foot bumps, the
air would be braked and pushed out to the side where it would disrupt flow. If the floor next to the foot
bumps is arched inwards, the cross-sectional area remains the same and the current can flow around the
foot bumps more easily.
Why are no wind tunnel tests done?
Because they are complex and expensive.
Also, it’s not that easy to generate realistic flow conditions. While an aeroplane is smooth on the outside
except for the engines and is only surrounded by air, a velomobile has rotating wheels in wheel wells as
well as the road, which is a few centimeters under the velomobile. For correct simulation, it is therefore
not sufficient to place the velomobile in the wind tunnel or to model it on the computer (so-called CFD si-
mulations), the wheels have to turn and the road has to move underneath it.
And last but not least: to get new insights, it is not enough to simply place a vehicle in the wind tunnel and
observe it. You have to set up and test hypotheses in a targeted manner, i.e. have a clear idea of what you
could change and how. And precisely because velomobiles are already pretty good aerodynamically,
further improvements can only be achieved if you know exactly what detail you are looking for.
Why is the large air intake at the front of the body?
Because he stagnation point is there.
If the air intake were further back on the fuselage, then you would have to somehow channel the air
inwards without the outside flow detaching from the fuselage – that would happen if an air inlet was in the
wind. On the other hand, as the air builds up in the front, you don’t need a device that directs the air in-
side, just a simple hole is enough. In addition, the flow is always there dueto the dynamic pressure, and an
air inlet there does not damage aerodynamics.
What is a NACA duct?
This is a triangular air inlet (see Fig. 21), which is located on the side of bodywork. The inventor and name-
sake is NACA, a US aeronautical research institute and forerunner of NASA.
If you want to bring air from the side into the interior of a vehicle, a simple hole is not enough – the air
flows across the hole and therefore not through the opening. One would have to redirect the air, however,
a corresponding “scoop” would increase the cross-sectional area and thus the air resistance, and possibly
create braking vortices behind it. The NACA duct takes a different approach: the opening is in the direc-
tion of travel (i.e. in the direction of flow), but offset inwards – this does not increase the cross-sectional
area. In order for the air to come in, there are two sharp edges in the direction of travel. It tears at this
edge, and vortices are formed that rotate inwards and come into the inlet opening. The NACA-Duct brings
the air inwards by creating inward vortices and then sucking these vortices away – so that the outside flow
is nice and smooth.
Fig. 21 : NACA-Duct on the bonnet of a Milan SL
Does ventilation slow you down?
Basically yes. The air hits the velomobile at driving speed and is braked inside – at the latest when it hits
the driver. The energy for the deceleration of the air (from the perspective of the velomobile) or the accele-
ration (from the perspective of the environment) must indeed come from somewhere, namely from the ki-
netic energy of the vehicle. On the outside, on the other hand, the air would be deflected but hardly slowed
down, meaning that less energy would be lost there.
Ventilation, on the other hand, has a positive effect if it succeeds in improving the external flow. For exam-
ple, the steep front of the bonnet creates a stagnation point, i.e. a “mountain of air” accumulates there,
which on the one hand makes the front of the bonnet less steep for the flow (see: Why is the front blunt
instead of being pointed?), but on the other hand increases the effective size of the bonnet – the air flow
has to flow around all the stagnated air and is therefore more difficult to get behind the bonnet/scoop. If
some of the air is now diverted inwards here, it ends up exactly where it is needed (by the driver or on the
inside of the windscreen, where it prevents the windscreen from fogging up), and not only is there no tur-
bulence on the outside, but the “mountain of air” accumulated there with its damaging effects on the flow
becomes smaller. It would also be positive if it were possible to divert an already swirled boundary layer
towards the inside, so that the flow outside is again nice and smooth. However, this happens mainly in the
rear part, behind the driver.
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Are freestanding wheels a lot worse than wheel wells?
At first glance, a velomobile with free-standing wheels like the Le Mans by Cycles JV & Fenioux looks very
attractive: the body is narrower yet the track is still wide, the steering linkage can be covered
aerodynamically, larger wheels are possible, and steering lock is not limited by wheel wells. And if the
wheels are covered with wheel disks, you would think that the aerodynamics should not be that bad either.
The problem, however, is that the top of the wheels are in the wind. Even a smooth tyre draws a lot of air
with it (with tread it is much worse), and with free-standing wheels, the top moves against the air at twice
the speed of the rotation. When the wheel wells are closed, the airstream is not attacked, the air in the
wheel wells is stationary relative to the vehicle, so that the wheels only work against the air at that speed.
Aerodynamic drag increases quadratically with speed, performance even cubic – i.e. a free-standing wheel
needs eight times the power at the top because of its double speed. Worse: the air transported there by the
tyres not only moves parallel to the tyres, but also to the side, where it hits the wind – i.e. the
aerodynamically effective width of such a wonderfully narrow tyre is much larger. And even worse: since
the wheels are not extremely far from the bodywork, these air turbulences also destroy the flow along the
bodywork (interference resistance; see: What is drag?). Wheels are relatively far forward, thus most of the
velomobiles laminar flow is destroyed. This is the reason why free-standing wheels are extremely poor
aerodynamically.
It would be different if you provided the wheels with wheel covers – one could make them very narrow
(because they steer in curves), and it is only important that the upper half or the upper 2/3 of the wheel
are covered.
How does wind make itself felt?
Headwind or tail wind is felt much less than on normal bicycles. You can see on the speedometer that the
speed differs slightly in headwinds or tailwinds, you don’t have the feeling of “pushing against a wall” in
headwinds.
Cross winds are noticeable mainly due to the influence on the steering, if you have a suitably sensitive ve-
lomobile, you should drive carefully in strong winds. The absolute force is not the problem, but its sudden
change – if you come out of the slipstream at the end of a hedge, for example, when driving downhill
quickly and a gust of wind suddenly pushes on the velomobile, you need a space of one meter to the side to
be able to compensate. So this is of course extremely unfavorable if it is a narrow street with oncoming
traffic. The actual offset by the wind is much smaller, but without warning you need very good reflexes to
keep the steering reasonably calm.
If the cross wind is very strong, it can also knock over a velomobile. This is not surprising, since the side of
a velomobile is not much smaller than a car (approx. One third), but weighs much less (approx. one tenth
with the driver), the ratio of the height (or height of the wind attack point) to the track width is also less fa-
vorable than in most cars. And so it can happen in a strong storm (approx. Wind force 9/10) that the wind
tips you in a straight line.
How can wind sensitivity be reduced?
Wind sensitivity can have various causes:
Caster: If the struts are not perpendicular (to the longitudinal axis of the vehicle), the wheel contact
point is not at the tracking point, but usually behind it. This tracking is desirable on a single-track be-
cause it stabilises the ride – the wheel follows the direction of the bike and counteracts tipping, so the
steering straightens itself. With a multi-track this is not only less important, but even counterproduc-
tive in windy conditions: if the wind pushes the vehicle to the side, the steering follows and steers the
velomobile away from the wind. Without caster, there is no lever through which the wind force could
exert torque on the steering. Caster can be reduced by adjusting the trailing arm.
Flow around: A body that is flowing around experiences a force, if this is undesirable, it can help to
deliberately break off the flow, for example with Stormstrips – these are thin, angular profiles that are
glued to the body in the longitudinal direction. Thus, they do not create any additional drag in the di-
rection of travel, but wind flow across the vehicle tears off and swirls there instead of creating lateral
lift.
Shape of the body: If the wind-attack surfaces of the body are asymmetrically arranged, the pressure
point is not in the centre of the vehicle, and thus a torque is generated which depends on the direction
of the apparent wind. Again, Stormstrips could help balance the wind forces better.
Centre of gravity and height of the point of wind attack: the higher the point of wind attack, the greater
the leverage over which it causes the vehicle to tip. And the higher the centre of gravity, the less it ne-
eds tobe lifted when tipping. So to make a vehicle less susceptible to tipping, you can set the centre of
gravity as low as possible (and as close as possible to the widely spaced front wheels), and use tricks
such as stormstrips to reduce the wind force on the top.
Swirling: At high speeds, it can be a problem for vortices to shed unevenly, causing the tail to become
unsteady. While this behaviour is basically dictated by the shape of the body, it is possible to provide
for small-scale turbulence, e.g. by a rough surface at the stern (golf ball effect), which prevents the for-
mation and detachment of large vortices.
What is the sailing effect?
Cross winds can provide propulsion, i.e. the velomobile “sails” forward. This is actually not surprising, be-
cause it has a relatively large side surface that the wind can blow along, it rolls easily, and it is very stable.
So like a sailboat – with a very small sail, but very little drag and an excellent keel without any drift. The
only problem is that a velomobile is usually much faster than the wind. That means: no matter from which
direction the wind blows, the apparent wind always comes more or less from the front – and for it to come
from the side at full speed, it has to blow quite hard.
A strong sailing effect does not necessarily imply a strong wind sensitivity (see: How can wind sensitivity
be reduced?) – if the body is shaped in such a way that a strong wind force is generated and this has a large
component in the direction of travel, this does not have to affect the steering, nor does it have to exert a
torque on the body, nor does it have to lead to unevenly detaching vortices.
The sailing effect varies in intensity depending on the velomobile model. A more detailed investigation has
so far only been made for the Milan GT 2011 in the Volkswagen wind tunnel, this has shown that the sail
effect exists and is strongest at a direction of the apparent wind of 75°.
Under what conditions is drag the least?
The shape and cross-sectional area of a vehicle are unchangeable, and you don’t want to reduce the speed,
you want to increase it – this leaves only the air density with which the air resistance can be changed.
There is the lowest possible air density:
At high altitude. However, physical performance also decreases with altitude, since oxygen supply to
the body becomes more difficult. Since oxygen is relatively heavy compared to the other air compo-
nents, the amount of oxygen available decreases disproportionately with altitude. Therefore, attemp-
ting records at 1000 m is a good idea, but not at 3000 m.
At high temperature. Then the rubber of the tyres is not as rigid and the rolling resistance is lower.
However, the body must not overheat, because otherwise the performance drops sharply.
In humid air. However, this makes cooling more difficult because sweat does not evaporate as well and
the body overheats more easily. In addition, raindrops on the surface interfere with aerodynamics, and
water on the road increases rolling resistance.
As you can see Battle Mountain in the Nevada desert at an altitude of 1375 m with a warm desert climate is
quite well suited for record attempts. But there is another reason why the records are set there of all pla-
ces: there are hardly any roads with perfect asphalt that are absolutely level over several kilometers.
Accordingly, the IHPVA allows in their rules, a maximum gradient of 2/3%. The Battle Mountain course is
very close, with a gradient of 0.64%. This is very little and is roughly in the range of the breakaway resis-
tance, this means that a bicycle does not roll off on this slope. But if a record driver is traveling at 113 km /
h, that’s a good 31 meters per second, with a gradient of 0.64%, that’s 20 cm difference in height per se-
cond, which means almost 200 W additional power for a weight of 100 kg – almost as much as a legal Ger-
man Pedelec motor gives at continuous performance.
Basic Physics
Note: The example calculations here always refer to a 75 kg rider in a 25 kg velomobile, in reasonably good
condition, but without record fitness.
What is rolling resitance?
Rolling resistance is fundamentally complicated because it is a collective term that includes many things:
Deformation of the tyre
Roughness of the road
Rolling and sliding friction in the bearings
In particular, the deformation of the tyre is not only geometrically complex, it’s hysteresis losses also de-
pend on the material properties of the rubber. And this is itself a complex combination of many substances
and a company secret of the manufacturer. What exactly happens there cannot be calculated – at least not
as an outsider.
Nevertheless, it shows that the rolling resistance is primarily dependent on the load. Accordingly, one
might summarize all influences on the rolling resistance value, which can be regarded as a constant, and
thus very well describes the rolling resistance in the relevant speed range. This constant has little to do
with the physical processes behind it, but it works well enough.
This is not enough for bean counters like velomobile drivers, here it has been shown that there is still a
small speed-dependent share in rolling resistance – and this is the so-called dynamic rolling resistance.
There are hardly any studies of the causes, only speculations. It is also an empirical factor that works well
enough, and with the help of which the rolling resistance can be adequately described within the scope of
measurement accuracy.
How do you reduce rolling resistance?
Tyre pressure: High air pressure = lower friction. But this only works to a certain degree, if the tyre is
already hard, it hardly deforms, and therefore, no matter how high the pressure, it can hardly be made
to deform even less. This increases the risk of tyre damage. And on rough ground, the tyre does not
spring, but jumps, which also costs performance (see: What tyre pressure? and Fig. 12). Therefore, a
good recommendation is to use the maximum pressure specified by the manufacturer and somewhat
less on rough roads.
Fast tyres: It largely depends on the rubber compound, which cannot be assessed from the outside.
Here you have to rely on the information provided by the manufacturers, together with practical
reports.
Thin-walled tyres: All fast tyres have in common that they are relatively thin-walled – tyre flanks
especially often have very little rubber. The less rubber there is, the less it has to be deformed, the los-
ses are correspondingly lower and the comfort is also higher because the tyre adapts better to the road.
Latex tubes or tubeless: The tube also contributes to the thickness and therefore rigidity of the tyre.
That is why a thin tube is better than a thick one, so use latex tubes or go tubeless (where the tyres are
a bit thicker). As one can see in Fig. 22 these tyres do not only roll better, but are also less sensitive to
reduced pressure – which better absorbs the braking vibrations.
Wide tyres: Geometrically, wide tyres are faster because the tyre contact patches are shorter and are
not deformed as much in the direction of travel. However, a wide tyre can withstand less pressure, and
is usually strongly built. Therefore, one cannot simply conclude the rolling resistance from the tyre
width, but must look at the entire tyre.
Fig. 22 : Rolling resistance of road bike tyres at 8.3 bar as well as its increase at
only 4.1 bar tyre pressure. As you can see, tubeless tyres not only have a low rol-
ling resistance, but this also tends to increase less at low air pressure.
Why are good tyres so important on a velomobile?
On a straight line at constant speed, the drive energy is primarily spent in air resistance and rolling resis-
tance. While the rolling resistance force is constant, the air resistance force increases quadratically with
speed, that’s why air resistance dominates on normal bicycles as soon as you roll more than just
comfortably (about 25 km/h).
It’s different with velomobiles. There the air resistance ismuch lower, so even at about 50 km/h air and
rolling resistance are approximately the same value (see Fig. 23). But hardly any velomobile driver
constantly drives more than 50 km/h where air resistance dominates. Because the air resistance is so
small, the share of rolling resistance is much larger, so that it dominates during most of the journey (see
Fig. 24). (On fast downhill sections, the air resistance clearly dominates, but that only makes up a small
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part of the driving time.) That is why good tyres are important for the velomobile, because it can reduce
the dominant rolling resistance. This goes so far that even the material of the tubes (Butyl or Latex) and
the ambient temperature noticeably affect the attainable speed.
Fig. 23 : Comparison of propulsion losses ( ), rolling resistance ( ) and
air resistance ( ) at different speeds. As you can see, air resistance is
completely negligible below about 15 km/h, and even at 50 km/h it is not even
half. This means that rolling resistance mostly dominates during the ride – ex-
cept for a few high-speed sections. On other bicycles, rolling resistance and drive
loss are roughly similar, but air resistance is significantly higher, by a factor of 5
to 10.
Fig. 24 : Histogram of the speeds of a long-distance ride (to SPEZI 2019, first
approx. 200 km). Assuming the same resistance coefficients and the same system
weight as in the other diagrams (and neglecting braking), we see that despite a
brisk speed (median: 36.7 km/h) about twice as much energy went into rolling
resistance (62%) as into air resistance (31%).
Why are velomobile riders so obsessed with low weight?
Many people say that low weight is not so important to them:
You won’t be racing, so gaining a second or two is not important, reliability is more important.
The weight saving is negligible in relation to the total weight (driver, vehicle and luggage).
Both are basically correct, but apart from the fact that reliability has little to do with weight (a light vehicle
is not necessarily more fragile, but only more elaborately manufactured), you have to look at the energy
balance. And that’s where air resistance comes in again – or its absence. While with a normal bike at high
speed a large part of the energy is used to beat air resistance, it is usually less than half of that in the velo-
mobile, despite significantly higher speeds. And the mass does not go into overcoming air resistance, but
into the following resistances:
Rolling resistance: This is usually the dominant resistance, and it increases linearly with weight.
kinetic energy: Since a velomobile can reach much higher speeds, the acceleration phases are also
much longer – the kinetic energy increases quadratically with speed, i.e. for twice the speed, four times
the energy has to be put in. Accordingly, acceleration phases account for a much larger proportion in
the energy balance (see Fig. 28 and How to achieve the highest possible average speed?).
Pchain Proll
Pair
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Uphill: Here you also notice the weight clearly, and because uphill the velomobile has no aerodynamic
advantage but a disadvantage due to its higher weight (see Fig. 31), the difference feels even stronger.
So with a velomobile, weight plays a bigger role, but at the same time it is significantly heavier – that is
why a weight reduction pays off more (see Fig. 25). And not only for sporty riders: the weaker a rider is
(i.e. the lower the speed), the lower the air resistance – and the rolling resistance has a greater share. In
addition, strong riders can often take hills with momentum (dolphining) on undulating terrain, while weak
riders have to lug their weight up without momentum.
And quite pragmatically: It is very pleasant when a velomobile is so light that you can carry it alone, e.g.
over a few steps or lift it onto a train, instead of always needing a second person to do it.
Fig. 25 : Additional power requirement due to luggage, for a road bike (dashed)
and for a velomobile (solid). At low speeds, the luggage plays a greater role on a
road bike because the bike is significantly lighter – the luggage therefore ac-
counts for a greater proportion of the total weight. However, this is also the case
with light riders. At higher speeds, air resistance is added, so weight is less noti-
ceable, but because a velomobile has less air resistance, the influence of luggage
weight remains much greater. Accordingly, especially light, low-powered riders
should pay attention to keeping the total weight as low as possible.
Why is it said that the wheels count twice in weight?
The following energy is required to bring a wheel up to a certain speed:
Kinetic energy: 
Rotational energy`: 
As you can see, both formula are quite similar:
 is the Moment of inertia`, it depends on the mass and its distance from the fulcrum. If you assume
that the mass is on the outside of the wheel, the following applies: .
 is the Angular velocity`, i.e. the number of revolutions over time ( ). Since the tread of the
wheel must move at driving speed, i.e. the circumference over time must be equal to the speed (
), we get: 
If you use this formula, the following results as rotational energy:
. This means that if the entire mass of the wheel sits on the
outside of the tread, the rotational energy is equal to the kinetic energy – hence the statement that the
weight of the wheels would count twice, because rotational energy and kinetic energy taken together are
twice as large as the kinetic energy of one rotating component.
In reality, the rim and tyre make up the largest part of the wheel, but the mass is not completely on the
outside, so the contribution of the rotational energy is smaller – so it is not quite twice as much. And as
you can see, the size of the wheel is irrelevant: a large wheel has a higher moment of inertia (into which the
radius is squared), but rotates correspondingly slower (the angular velocity is also squared) so that the ro-
tational energy is the same.
But how much does this effect matter in practice? Suppose you have a velomobile with a system weight of
100 kg, its wheels weigh 4 kg. Their rotational energy is correspondingly about 3% of the kinetic energy. At
50 km/h, the kinetic energy is 9645 J, together with the rotational energy of the wheels, this is about 10 kJ.
If you manage to make the wheels 500 g lighter on the outside, this corresponds to a weight reduction of 1
kg, and for acceleration to 50 km/h 100 J less have to be applied. With a pedalling power of 300 W, it ta-
kes almost a minute to reach 50 km/h – but the 100 J saved correspond to only a third of a second of pe-
dalling power. Moreover, the rotational energy is not lost if you don’t have to brake it away. Therefore, it
does not play a major role in normal cases.
Why is it so difficult to to drive faster?
Top speed is mainly determined by air resistance – because this increases faster than other driving resis-
tances. The air resistance force increases quadratically with speed, so to travel a distance twice as fast re-
quires four times as much energy for air resistance. But since you then cover the distance in half the time,
you have to provide the aforementioned four times the energy in half the time – work per time is power, so
you have to provide eight times the power for twice the speed. (This is somewhat simplified and only
approximately valid for very high speeds, since air resistance is only a part of the total driving resistance, it
increasesor its successors, or were
involved as suppliers. That’s why the local proximity is no wonder. And for the same reason, many models
use the same shock absorbers and the same tiller – they fall back on tried and tested components from
friendly companies. Since several manufacturers have now moved their production to Velomobile World
in Romania, there will probably also be some shared components and similar production processes in the
future.
http://velomobiles.de/html/modellubersicht.html
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Fig. 8 : Velomobile family tree (large version online), there are close personal
links between the Dutch and also partially some German manufacturers.
Are there velomobiles for more than one person?
At least the Leiba Cargo can carry a passenger, and a very small person or child fits in the Quattrovelo.
However, they cannot join in and pedal. Real tandems exist but only as prototypes, not as a series. Only
the DuoQuest is now being built as a small series, but it’s more of a fun vehicle and not particularly fast.
But the point of having a tandem is also somewhat questionable: a velomobile tandem is much heavier
than a solo, and if you drive it alone also much slower. In addition, it is not cheaper than two separate ve-
lomobiles and also not more efficient. (A correspondingly highly optimised tandem velomobile is conceiva-
ble, but has not yet been built, and would only have minor advantages and significant disadvantages with
much larger external dimensions and a larger turning circle).
Which model is the best?
It depends on your requirements:
First of all, it has to fit you and you have to feel comfortable in it. For an average sized velomobile dri-
ver (approx. 1.70–1.90 m) this is much easier than for very tall or short people.
The seating position also differs, in some one sits more upright and in others almost lying down. So it
depends on your prefered riding style.
Some models are particularly fast because they are as light and stiff as possible. But they also tend to
be more uncomfortable (less space, firmer chassis).
Some models offer a particularly large amount of storage space for luggage or for bulky items.
Some models have a particularly large opening for entry.
Depending on the route, models with larger widths can be impractical.
Depending on your garage space, particularly long models can be hard to park.
So there are many criteria, you can (and should) look at the technical data and tests and reviews, but
whether it really fits you or not you will only notice during a test drive. Even if your body length fits, it may
be too tight at the shoulders, for example.
How complete should a test drive be?
Hard to say, you will see if you fit in it, if you can see out and can pedal without problems. But whether a
Velomobile is really the right thing for you, you won’t know after a short test drive – your muscles have to
adapt over several 100 km, and an efficient and correct driving style takes weeks to months to master. And
finally can a velomobile work for you on your everyday routes? For example in city traffic where it hardly
shows its qualities. If you are unsure you should take into account that you may have to resell the velomo-
bile – or it maybe best to buy a cheap used one to start off with to gain your first experiences.
Can you build a velomobile yourself?
Of course, most of the parts can easily be made in the home workshop, and the special components such as
struts can be obtained from the manufacturers. However, a velomobile made of GRP/CRP is very tedious
because you have to produce a master model and a negative mold - that’s why most hobby projects use
other materials such as plywood or aluminum.
There are also some blueprints/building instructions; E.g. for the Agilo (made of plywood; design by Bodo
Sitko) or the Meufl asphalt pedal boat (frame in positive carbon construction, body made of foam; by Ha-
rald Winkler).
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https://www.sitko-velo.de/
A few velomobile models were also sold as kits that only required assembly; Eg various Alleweder models
(A2, A4, A4, FAW) and infrequiently some Go-One models.
If velomobiles are so fast, why don’t you see them in bike
races?
Competitive cycling, especially in the professional sector, is almost entirely run by the UCI (Union Cycliste
Internationale). This organisation has proven to be very conservative in the past. Not only are recumbent
bikes forbidden in their set of rules, but even triathlon bikes and all sorts of other innovations and optimi-
zations - only classic diamond frames are allowed. And professional cyclists only ride the races where
money can be made - namely those of the UCI - and use the appropriate material.
But there is another reason: in conventional cycle races, a lot of energy can be saved by slipstreaming be-
cause the air resistance is much lower. On the other hand, in a velomobile race, drag is always low, so there
is no reason to form a peloton. Accordingly, the team, management work and tactics play a much smaller
role, the performance of the individual is much more important - a race would therefore have more of the
character of an individual time trial and would therefore be more predictable and less exciting.
Body and geometry
Why do Velomobiles have three wheels?
A two-wheeler without fairing is significantly more compact than an unclad tricycle, and a whole lot lighter
because a wheel and the steering and possibly suspension mechanisms are omitted. This is no longer so
clear with bodywork, the vehicle is wide, regardless of whether it has two or three wheels, and together
with the weight of the fairing, the relative weight difference is significantly smaller. Another reason is the
wind sensitivity. A fairing means a lot of exposed side area for cross winds, and a two-wheeler is more sen-
sitive to this because it is narrower and taller, so it offers even more side surface. In addition, you can not
easily put your feet on the ground to catch a fall on a faired two-wheeler. That is why multi-track velomo-
biles ultimately prevailed because they are not that much heavier and slower than single-track velomobi-
les, but are more relaxed to drive, especially at high speeds and on long journeys.
Why are there usually two wheels in front and one behind?
There are two reasons for this:
First, driving stability. In a curve, the force of inertia pulls the vehicle tangentially out of the curve.
With two front wheels (so-called tadpole arrangement), the front wheel on the outside of the curve is
exactly in the direction in which the inertia is acting – the vehicle cannot tip over so easily. If there are
two rear wheels (so-called delta arrangement), there is no wheel there, so it tilts more easily.
Second, the aerodynamics. It is easier to build a fast vehicle with the front wheels forming the widest
part and close to the front or in the middle. If you had the two wheels in the back, you would have a
long, unused space behind the rear wheels – while the rear wheel fills this space in a tadpole
configuration.
Why are the front wheels small and the rear wheel big?
The front wheels are small for space reasons – if you wanted big wheels in closed wheel wells then the
vehicle would have be very tall, and since you want to steer with the front wheels, the wheel wells would
need to be deep enough, which in turn increases the overall width. So you make the front wheels no higher
than the interior space that the recumbent cyclist needs for pedaling.
The rear wheel,more slowly, see: Why don’t you accelerate in a velomobile “like against a wall”?)
A second limiting factor is the large amount of kinetic energy that has to be built up (see Fig. 28 and Why
are the acceleration phases so long in a velomobile?). This is because it takes a lot of time and distance –
especially at high speeds, a large part of the pedalling power is already consumed by the driving resistan-
ces, so that only little power is left for further acceleration. This means that you only accelerate very slowly,
but because of the already high speed you need a lot of free distance to do so.
Ekin = 1/2 × m × v2
Erot = 1/2 × J × ω2
J
J = m × r2
ω 2π/T
2 × r × π/T = v ω = v/r
Erot = 1/2 × m × r2 × (v/r)2 = 1/2 × mxv2
https://cmoder.gitlab.io/velomobil-grundwissen/_images/speed_vs_power_luggage_en.svg
https://cmoder.gitlab.io/velomobil-grundwissen/_images/speed_vs_power_luggage_en.svg
And a third problem is time: If you need 20 minutes for a certain distance at a certain speed, you can save
10 minutes by doubling the speed – but (if you only consider the air resistance) you have to produce eight
times the power. A further doubling of speed again results in eight times the power requirement (i.e. 64 ti-
mes the power in total), but only saves a further 5 minutes (i.e. only saves a further quarter of the original
journey time).
How fast can a velomobile go?
With a velomobile air resistance is significantly lower and the theoretically achievable top speed is
significantly higher than that of other bicycles. However, kinetic energy is not less – due to the higher
mass of a velomobile, it is even slightly higher. The speed is quadratic to the kinetic energy, in order to
drive twice as fast, you not only have to achieve eight times the power to overcome the air resistance, but
also four times the kinetic energy during acceleration.
If you can achieve 400 watts, for example, it takes almost one and a half minutes and 1.1 km to reach 65
km/h (system weight: 100 kg). If you drive downhill, you get quite a few watts from the slope, however, as
the speed increases, the necessary downhill section becomes longer and longer: if you go downhill at 3%,
for example, you can reach around 104 km/h with 400 watts of pedaling power in two minutes – but the
downhill section must also be almost 1.7 km long and have 160 m difference in altitude – and be
significantly longer for the braking distance without curves or obstacles. And it would take even three ti-
mes the time and distance to reach the terminal velocity of 118 km/h (see Fig. 26). Therefore, a trained dri-
ver rarely ever reaches 100 km / h in ideal conditions, although much more should be possible on an ideal
gradient.
Fig. 26 : Comparison of acceleration: If you pedal at a constant 400 W, you ac-
celerate faster at the beginning than if you roll downhill with a 3% gradient. But
on the downhill you accelerate more strongly at high speeds and reach a
significantly higher top speed, because with increasing speed the altitude energy
released per time also increases, so that after 180 metres of descent more than
twice the driving power (without drive losses) is effective.
Are Velomobiles faster because of their high top speed?
Not really. Since people are quite underperforming, the maximum speed that can be achieved depends
more on the gradient than on the pedaling power (see Fig. 26), and since high top speeds require very long
acceleration distances (see Fig. 34), in practice the maximum speeds of velomobiles and other fast bicycles
are not all that different.
But what is significantly different with a velomobile is that you can keep a high continuous speed much
longer than with another fast bike – if you do not have to brake.
Why don’t you accelerate in a velomobile “like against a
wall”?
With aerodynamically poor bicycles, you feel a relatively clear maximum speed, even with significantly
more effort, you no longer get appreciably faster. This feels different on a velomobile: you don’t “pedal un-
til you’re hitting a wall”, but can accelerate further more easily (which only takes a correspondingly long
time and requires a correspondingly long distance, see Why are the acceleration phases so long in a velo-
mobile?). The reason is the high proportion of rolling resistance (see Fig. 23), as this increases more slowly
than air resistance, the total resistance also increases with a lower power (see Fig. 27) – so at the same
speed, not only is the total resistance lower on a velomobile than on a conventional bicycle, but the total
resistance also increases more slowly there, and so it is easier to go even faster.
https://cmoder.gitlab.io/velomobil-grundwissen/_images/acceleration_400W_downhill3pc_en.svg
https://cmoder.gitlab.io/velomobil-grundwissen/_images/acceleration_400W_downhill3pc_en.svg
Fig. 27 : Effective exponent by which the driving resistances increase with speed,
at different gradients, the solid line is a velomobile, the dashed line is a racing
bicycle. The various driving resistances increase with speed at different rates,
while rolling resistance (which is not speed-dependent) increases linearly with
speed, air resistance increases cubically. But because rolling resistance is a large
component of total resistance on a velomobile, it effectively grows only
approximately quadratically even at high speeds, whereas on a road bike it is
much closer to cubic growth. Uphill, the effective exponent is smaller because the
climbing work, which only grows linearly with speed, is added – the total resis-
tance is of course much higher uphill than on the flat, it just grows more
slowly.
Why are the acceleration phases so long in a velomobile?
In any case, it is not due to inefficient power transmission or a higher total weight – as you can see in Fig.
34, a velomobile accelerates practically as well as any other bicycle – at low speeds, the higher mass is no-
ticeable, but from about 30 km/h onwards, this is overcompensated by the low air resistance.
Nevertheless, the acceleration phases are very long – so long that you can’t sprint back to cruising speed
after every braking, but have to divide your power. With other bicycles this works well, and is even recom-
mendable from an efficiency point of view (see: How to achieve the highest possible average speed?), with
the velomobile, however, you would totally exhaust yourself if you wanted to ride the long acceleration
phases with a high sprinting power.
The reason for this is: With the velomobile, the air resistance is small, but not the kinetic energy. So you
can ride at high speeds, but you have to build up the necessary kinetic energy first. As you can see in Fig.
28, at 50 km/h the kinetic energy is more than 50 times the energy needed for air resistance, rolling resis-
tance and drive losses per second at that speed. Or to put it another way: someone who kicks enough con-
tinuous power to drive 50 km/h (in our example, that’s about 179 W) first has to do twice as much for 40
seconds to accelerate the vehicle upwards – and needs 400 metres of free distance to do it. And then when
a red light comes, it starts all over again.
With any other bicycle, by the way, it would take just as much effort and time to build up the kinetic energy
needed for high speed – you are just stopped much earlier by air resistance.
That, by the way, is the reason why in Battle Mountain a run-up of 8 km is taken even for the 200 m
sprints – there is no other way to build up the kinetic energy for 130 km/h, the measuring distance itself is
then passed in a few seconds. And it might also be one of the reasons why long-distance endurance records
are popular in the velomobile scene – because there you only have to accelerate once, and then “only”
maintain the speed.
Fig. 28 : Comparison of the kinetic energy with the driving resistances, the refe-
rence value is the energy consumed by the driving resistances in one second.
Since in the velomobile the driving resistances are lower at high speed, the build-
up ofkinetic energy is much more significant.
https://cmoder.gitlab.io/velomobil-grundwissen/_images/speed_vs_power-exponent_en.svg
https://cmoder.gitlab.io/velomobil-grundwissen/_images/speed_vs_power-exponent_en.svg
https://cmoder.gitlab.io/velomobil-grundwissen/_images/kinetic-energy_ratio_cWA_en.svg
https://cmoder.gitlab.io/velomobil-grundwissen/_images/kinetic-energy_ratio_cWA_en.svg
Why is performance data alone meaningless?
Since power meters are now widely available, many velomobile riders indicate how much power they nee-
ded to go a certain speed. However, power requirements depend on many things:
Weight of rider and vehicle
condition of the road (rough, smooth)
which tyres, at what air pressure
temperature, wetness of the road
Without the specification of these boundary conditions, however, a performance specification is not worth
much. Firstly, it determines the rolling resistance (see: Why are good tyres so important on a velomo-
bile?), and secondly, the acceleration work – because of the long acceleration phases (see: Why are the ac-
celeration phases so long in a velomobile?) you rarely ride at a constant high speed. And so it can happen
that a only moderately efficient velomobile achieves fantastically low wattage values if the rider is a
lightweight and only rides in good conditions and on good roads.
Why do cars accelerate better even though they are
heavier?
Because they have much higher power reserves.
An average-sized athletic cyclist can indeed produce many hundreds of watts – but only over a few se-
conds. Over a longer period of time, it is more in the order of 200 watts. As you can see in Fig. 23, you can
do a good 50 km/h with it in a velomobile. However, the power requirement uphill or when accelerating is
a multiple of this (see How to achieve the highest possible average speed? and Why are the acceleration
phases so long in a velomobile?). For example, the kinetic energy at 50 km/h is already just under 10 kJ,
for a car, accelerating from 0 to 50 km/h in 10 seconds is pretty lame, but a cyclist would have to muster
an average of 1000 watts for this in addition to the other driving resistances. Only a professional athlete
can do that.
A car needs 13 kW for 100 km/h (with the data from Fig. 19 and 1000 kg) – converted, that is just under 18
hp. But hardly any car has less than 100 hp. A leisurely acceleration from 0 to 50 km/h in 10 seconds only
takes an average of 13 hp – so together with the driving resistance, the car needs less than a quarter of its
maximum power (which a car cannot produce for just a few seconds) instead of having to expend all its
energy on it like a cyclist.
Uphill, by the way, it is similar: to ride up a 5% incline at 50 km/h requires almost 1000 watts with the ve-
lomobile – hardly feasible even for a professional athlete. A 1000 kg car needs a good ten times that power
(over 11 kW), but these 16 or so hp are ridiculous for a car. This only slowly reaches its limits when driving
on the motorway through the Kassel hills (up to 8%) at well over 100 km/h.
How to achieve the highest possible average speed?
Actually, it is quite simple: only the energy invested in rolling and air resistance is lost (and of course the
braking energy), in contrast, acceleration and climbing work is converted into another form of energy and
can be recovered again. And of the losses, it is only air resistance that increases strongly with speed. There-
fore, it is energetically most favourable to travel at as constant a speed as possible.
On the other hand, the body wants power output to be as constant as possible – high power peaks require
anaerobic metabolism and fatigue the muscles.
What does this look like in numbers?
As you can see in Fig. 31, for the calculated example velomobile, the power demand at 1% incline is
about twice as high as on the flat (slightly less at high speeds). Because of the small-angle approxima-
tion, one can accordingly assume that one needs three times the power for 2%, four times the power
for 3%, and so on. Uphill, therefore, you can spend an extreme amount of power if you want to main-
tain your speed. Or vice versa: If you assume that on uphill gradients at correspondingly low speeds
the power increases approximately linearly (this is quite true, see Fig. 27), then at the same pedalling
power the speed at 1% gradient is only half as high, at 2% gradient only a third, etc.
Acceleration is a little more difficult to describe, because you don’t consciously ride with a certain ac-
celeration power – you accelerate with the remaining power, after subtracting all the other riding re-
sistances. But in the end, acceleration can be described in the same way as an incline – because with
the latter, the acceleration due to gravity is effective, which is 9.81 m/s². So a 1% gradient that doubles
the driving resistance corresponds to an acceleration of 1% of the acceleration due to gravity, that’s
about 1/3 km/h per second. This is not particularly fast – at this acceleration, it would take just under
five minutes to go from 0 to 100. In practice, however, you accelerate much faster because it takes less
time, as you can see in Fig. 32, 50 km/h corresponds to a hill of only about 9 m height, i.e. it is easier
to sprint away than a high hill, and you are faster for it. (As you can see in Fig. 34, the acceleration dis-
tances are still long enough even with strenuous pedalling). So you often invest a multiple of the dri-
ving resistance, but only for a few seconds.
It is quite different when riding at constant speed on the flat. Of course, the drag power increases
cubically with speed – but firstly, this is no longer true for the total drag (see Fig. 27), and secondly,
the power does not vary so much here – between comfortable cruising and sporty riding there is
perhaps 30% more speed, which then corresponds to just twice as much power (see Fig. 23). On the
other hand, this is not a sprint of a few seconds, but the power is delivered over minutes to hours.
The human body is not so easy to calculate (and is also individually different). But at least the concept
of Normalized Power could give a hint. This describes how strenuous a certain average performance is
perceived to be. Here, a moving average of pedalling power over 30 seconds is calculated and taken to
the fourth power. Low and high power do not cancel each other out, but strong deviations from the
average power in both directions are clearly noticeable.
In summary, this means that although losses increase disproportionately with speed, both on inclines and
accelerations the power required can multiply at the same speed. However, the body reacts very sensitively
to power fluctuations – at least over minutes, not seconds. Therefore, you have to find a compromise: On
the one hand, don’t let the speed drop too much, on the other hand, keep the averaged power constant.
Uphill, this means sprinting away short ramps and recovering on the flat – but taking long climbs
comfortably. That’s why dolphining is so efficient on small hills: you don’t exhaust yourself because
the average power is not excessive, but your speed still doesn’t plummet.
When accelerating: Get up to cruising speed quickly, and then ride along comfortably. However, while
you can easily sprint to top speed in a few seconds on a racing bike, the acceleration processes are
much longer on a velomobile because of the higher top speed and thus much higher kinetic energy.
Therefore, you should accelerate quickly as long as the driving resistance is still low – but not
immediately up to the final speed, but divide the forces. Otherwise, routes with frequent braking and
acceleration will be very strenuous, but hardly faster. This is not to say that a velomobile is
fundamentally slow in frequent stops in city traffic – as you can see in Fig. 34, accelerating to the same
speed takes about the same time as a road bike. But higher speeds are not achievable due to lack of
free track.
And on the flat, it doesn’t do much good tobe maximally fast if you lack the grains elsewhere. It’s bet-
ter to rest here. Or slowly build up additional speed to be able to ride the next climb with more
momentum.
Last but not least, the average speed is the time average, i.e. slow sections have more weight than fast
sections.
So you don’t ride fast by having a high number on the speedometer as often as possible – but a very low
number as seldom as possible.
Does tilting technology for velomobiles make sense?
With tilting technology you can drive faster through bends they say. But that’s only partially true, whether
the vehicle is traveling up or down through a curve usually does not change the possible speed at all (if the
position of the cente of gravity is the same).
The first limiting factor in cornering speed is losing grip. In addition to the surface quality of the road, this
mainly depends on the tyre material – a good tyre should roll easily, but have a lot of grip in the corners.
There there are actually models that use different rubber compound in the middle of the tread than on the
edge, so that you drive straight on the smooth-running rubber, but when you corner, you are on the better-
adhering rubber. Of course, this effect cannot be exploited in a multi-lane vehicle without tilting
technology.
The second limiting factor is tipping over. And that mainly depends on the height of the cente of gravity
(as low as possible) and its distance from the outside wheel (as large as possible). With tilting technology
you can of course move the cente of gravity towards the inside of the curve, thus increasing its distance
from the wheel on the outside of the curve. But you can also do this by simply leaning towards the inside of
the curve – provided you have a seating position with sufficient lateral support where possible.
So tilting technology would actually have certain advantages, but also higher weight, greater technical
complexity, and that also needs space. You can shift the cente of gravity laterally with tilting technology,
but you will probably not get it as low as without tilting technology. Even if you don’t lean the whole vehi-
cle, but only the heaviest part – the driver. And then you also need an energy source that performs the in-
clination in the opposite direction to the centrifugal force – if you do it by hand, you can immediately do
without the mechanics and simply lean your body inwards. There is something like a passive tilting techni-
que, but in principle the vehicle is suspended on the chassis like a swing – yes, it tilts in the curve of its
own accord, but that only prevents you from slipping on the seat, you can’t drive faster through the curve,
but on the contrary, only slower (because the cente of gravity swings outwards instead of inwards).
And last but not least there are very few tight bends in practice that could be driven at high speed, real cur-
ves are usually wide enough, and with narrow junctions you rarely have the overview to drive through
without slowing down. For these few special cases and a few seconds saved, complex mechanics are not
worthwhile.
Measurement and Optimization
How to measure rolling resistance?
In order to minimise air resistance, the test must be carried out at low speed.
To rule out uneven pedalling, a rolling test is recommended. (See also: How do you know if tracking is
set correctly?)
To rule out environmental influences, it should be a windless track with perfectly even asphalt and no
bends.
The height energy lost then corresponds to the energy spent on rolling resistance – the lower this is,
the greater the distance rolled.
How can I measure air resistance?
In order for air resistance to dominate, the test must be carried out at as high a speed as possible, for
example, 70 km/h.
To exclude the uneven pedalling power, a rolling test is recommended.
Since at high speed the acceleration phase costs a lot of energy and therefore takes a long time (see:
Why are the acceleration phases so long in a velomobile?) and thus rolling resistance plays a major
role during this time, the beginning of the rolling distance should be as steep as possible in order to re-
ach the measured speed as quickly as possible. For 70 km/h, 20 metres of altitude would be necessary.
The following measuring section should then be a constant downhill, where the velomobile rolls at a
constant speed, for 70 km/h this would be just under 2% downhill (see: Fig. 15).
At the end, there is then ideally a steep counter-climb where you come to a stop quickly, the difference
in height between the start and end position then corresponds for the most part to the energy that was
expended for air resistance.
The cross-sectional area of a velomobile can be drawn by projecting it with a light source that is as pa-
rallel as possible (= as far away as possible, e.g. sunlight), and then e.g. cutting out the drawing paper
and weighing it to determine the area. Thus one can finally determine the value from the air
resistance.
How to measure drivetrain losses?
Since it is about the difference between pedalling power and riding power, a rolling test is unsuitable,
but here the pedalling power must be recorded with a power meter.
In order to minimise the influence of air and rolling resistance, one rides up a steep hill, then the
necessary climbing power is much higher than these losses.
In addition, one precisely determines the difference in altitude between start and finish as well as the
total weight with rider.
The pedalling power varies a lot, but added up over the whole ride it should correspond quite well to
the climbing work expended plus the riding resistances. Therefore, one can simply multiply the ave-
rage power by the riding time.
While air resistance is virtually completely negligible at these low speeds, rolling resistance is not, it is
only a few per cent of the total resistance, but since drive losses are of a similar order of magnitude,
one must know the rolling resistance coefficient at least reasonably well. Since the rolling resistance
force is largely constant (except for dynamic rolling resistance), the speed does not necessarily have to
be constant in order to calculate the rolling resistance losses simply using the average speed.
The difference between the measured muscle work and the sum of rolling resistance and the climbing
work calculated from weight and height difference are then the propulsion losses.
Can air and rolling resistance be measured at the same
time?
There are methods that use regression analysis to search for parameters that describe the measured data
well. A particularly interesting method is Robert Chung’s
`__ method, in which a hilly cir-
cuit is run several times at different speeds. It must be as windless as possible (however, on a circuit the
wind eventually comes from all sides), and one must not brake. Since it is a circuit, an exact measurement
of the absolute altitude is not so important either – even if the altimeter drifts slowly, you know that the
lowest and the highest points of the track must always be at the same altitude, and accordingly you can ad-
just the parameters for rolling resitance and air resistance so that the calculated net altitude gain becomes
zero. (Speed-dependent errors in the altitude measurement, as seen in Fig. 18, on the other hand, are very
much a problem, in this case one should resort to external altitude data). The evaluation is supported, for
example, by the software GoldenCheetah.
Is there a calculator for air and rolling resistance?
Yes, even several:
Kreuzotter calculator: Calculates the final speed or pedalling power from numerous parameters, and
includes presets for various upright bikes, recumbents and velomobiles. This variant of the calculator
even allows free input of rolling and drag coefficients.
HPV Speed Simulator: This calculator is similar to Kreuzotter, but also graphically displays the incre-
ase in speed, so you can also see howlong it takes to reach approximate final speed.
Power Analysis Graph: Here you can upload a file with recorded power data, and get a graph showing
the different driving resistances at any given time (see Fig. 29).
Velomobile simulator: Here you can enter the curves of the altitude profile and pedalling power in a
diagram and calculate the speed of a velomobile from this.
On the respective pages there are also sample values for air and rolling resistance coefficients. These were
mostly obtained from performance measurement data, so the calculations from them are reasonably
realistic.
cW
https://cmoder.gitlab.io/velomobil-grundwissen/dynamicrollingresistance
https://wallace78tria.files.wordpress.com/2013/02/indirect-cda.pdf
https://www.goldencheetah.org/
http://kreuzotter.de/deutsch/speed.htm
http://infotom.de/kreuzotter/
http://www.recumbents.com/wisil/simul/HPV_Simul.asp
https://christoph-moder.de/fahrrad/powermeter2diagram.php
https://christoph-moder.de/fahrrad/vm-simulator.php
Fig. 29 : The power analysis diagram that calculates and displays the rolling re-
sistance, air resistance and other power data for a recorded ride with altitude
profile and power data.
https://cmoder.gitlab.io/velomobil-grundwissen/_images/powermeter2diagram.png
https://cmoder.gitlab.io/velomobil-grundwissen/_images/powermeter2diagram.png
Ergonomics
What are the limiting factors in size? What do you have to
watch out for?
Leg length: Since the velomobile tapers at the front, the feet rub against the bodywork if the legs are
too long. The knees can also be a problem.
Upper body length: small people can not look out over the nose, and tall people do not fit under the
hood.
Shoulder width: in rare cases, a velomobile is too narrow at the shoulders.
Thigh width: with large thighs you no longer fit between the wheel wells. Since you have to move your
legs, absolutely nothing should rub on the bodywork here.
Foot length: people with large feet usually have long legs and may also want to use longer cranks, ove-
rall, this ensures that the feet rub against the side of the bodywork and/or below and above.
Preferences: e.g. flat or upright sitting position
Technical features: For example, for riders with short legs, where the bottom bracket is far back, the
chain often runs very steeply down to the idler pulley. This can lead to problems with the front derail-
leur, which – depending on the size of the chainrings – cannot be adjusted far enough.
What is the ideal sitting position?
Basically, it has to feel pleasant – some people prefer a steep sitting position, others prefer a flat one. Up-
per body opening angle (i.e. the angle between the upper body and legs) must be correct, many people can
exert more pedaling power when sitting upright.
Compared to an unclad recumbent bike the bottom bracket height in a velomobile is rather low. While
with the recumbent bike the legs are in front of the body, reducing cross-sectional area would not work in
a velomobile – you still have to look over the hood, so the legs are lower. In addition, the low aerodynamic
drag of a velomobile does not primarily result from a small cross-sectional area, but from a low drag
coefficient.
What is the impact of a short crank?
A short crank means that the lever that turns the chainring is shorter – at the same pedal frequency thus
requires more power and less distance (= less circumference of the pedal circuit), the pedal speed drops.
Conversely: To pedal with the same force and pedal speed, you have to drive in a lower gear than with a
long crank. Since the pedal circumference is smaller, the same pedal speed means that the cadence is
higher.
You also have to push the bottom bracket forward so that the leg is stretched equally when the crank is in
the front. The leg is then angled significantly less in the opposite crank position.
Why do recumbent riders often use short Cranks?
Of course, the crank length depends strongly on personal preference and habits, and of course also on
anatomy – longer legs need longer cranks. Apart from that, shorter cranks have proven themselves be-
cause the seating position is more fixed than on an upright bike (i.e. there is no out of the saddle) and at
the same time significantly higher pedalling forces are possible (i.e. you can not only push on the pedal
with your own weight but also push against the seat). This leads to high forces with strongly bent legs,
which can cause knee problems. On upright bikes, on the other hand, it is rather unusual to stay
completely in the saddle when pedalling powerfully – but when you pedal standing up, at top dead centre
your leg is hardly bent at all. With short cranks on the recumbent, the knee is less bent, i.e. experiences the
highest load in a position where there are less shear forces.
In velomobiles, however, there is also a purely geometric reason for short cranks: with long legs, the bot-
tom bracket is far forward – i.e. where the body is narrower and lower than further back. At the same time,
tall riders usually have large feet. In order to still be able to pedal without bumping your feet on the top
and bottom, the cranks have to be shorter.
On an open recumbent, on the other hand, there are aerodynamic reasons: if the legs extend less thanks to
short cranks, then less air is swirled.
How do I shorten cranks?
Most pedal cranks have a length of approx. 170 mm, shorter than 165 mm is usually difficult to obtain.
That’s why you have to shorten yourself or have the cranks shortened.
In itself, it’s pretty easy if you have the right tool: drill a hole and cut a thread. Since pedal thread has a di-
ameter of a good 14 mm, you cannot simply place a second hole next to the existing one at a closer distance
– because the new hole must be surrounded by sufficient material, it is advisable to use a crank that is 20
mm longer than the desired length.
Solid aluminum cranks can of course be shortened without any problems. But also hollow-forged cranks
are usually not a problem – you only drill the edge of the cavity, where there is still enough wall thickness
for the thread. An exception are rotor cranks, for example, because they contain several cavities next to
each other – among other things, where the thread would be on the side. Also carbon cranks cannot be
shortened eaasily, since the thread cannot be cut directly into the carbon (which would mean point loads
much too high), but is done via metal inlays.
What is the Q factor and why is it best to make it small on a
velomobile?
The Q factor is the width between the cranks, i.e. the lateral distance between the pedals. It is determined
by the width of the bottom bracket, the width of the crank arms, and their offset.
In the case of an upright bicycle with wide tyres, the chainstays must offer enough space, therefore the Q
factor must not be too small. Accordingly, the cranks are offset to get past the wide chain stays at the rear.
But the chainrings can also come into contact with the chainstay if they sit too far inside, so the bottom
bracket should not be too narrow there either.
With a velomobile, on the other hand, there are no chainstays at the bottom bracket, even the widest bot-
tom bracket mast is even narrower than a bottom bracket. There is therefore no reason for a large Q factor.
On the contrary, with a tall rider (= long legs, big feet) the feet can easily touch the bodywork if they are
too far apart. For this reason, attempts are being made to keep the Q factor small – for example, by shorte-
ning the bottom bracket axis a little and using cranks that don’t have much offset.
And last but not least, it is also more pleasant for many drivers to be able to put their feet closer and keep
their legs parallel.
High or low cadence?
Depending on personal preference and anatomy, but also habit. Both have advantages and disadvantages,
since low cadence means high strength and vice versa.
It is often said that too high a pedaling force would break the knee joint. This is only partially true, becausea trained knee can easily withstand great forces. But you shouldn’t go untrained on long tours using high
strength, but with a slower approach. The direction of movement also plays a role: a joint can withstand
very high forces if it is only subjected to pressure. If it still has to move, complications are much more
likely – therefore a pushing movement with short-term high strength should be much less critical than a
grinding movement with constantly high strength.
But even a high cadence is not necessarily a problem. In order for a knee to be free of symptoms, well-trai-
ned muscles that hold the joint in position – and muscles only develop under load, and not if you only ever
crank there without force. It also needs a certain alternating load because articular cartilage has fluid and
therefore nutrients that pump into the interior.
The cadence also has an effect on technology: a bike with a very responsive suspension bounces more
when the cadence is low and uneven – because there the mass of the legs is accelerated and braked more.
Accordingly, more energy is lost into the suspension damping. But you can change the pedaling force fas-
ter than the cadence, those who pedal at a high frequency need a better-tuned gearshift because they can-
not jump gears when accelerating as easily as a powerful driver.
Uphill the cadence gets lower for most people. This also makes sense because the pedal resistance is higher
there, i.e. in the dead cente speed drops more – and you need more strength behind the dead cente. In
contrast, the load is more even in the plain, it would be counterproductive to exert a high shear load on the
knees with a very slow and grinding movement over the entire pedal rotation.
Everyday use
How does a velomobile drive?
Good question – in any case, clearly different from other bicycles:
The speed is higher, so you have to ride much more carefully.
Acceleration phases are much longer, so you have to manage your power well and ride with foresight
(see Why are the acceleration phases so long in a velomobile? and Fig. 34).
Distances seem shorter because you usually ride faster.
Luggage is less critical – you don’t have to carry extra bags or straps and you don’t have to pack your
luggage in a special way, you can just carry it clean and dry inside (see: How much luggage can I
accommodate?).
You hardly notice the wind, because headwinds slow you down much less, you can see a slight diffe-
rence on the speedometer, but you don’t have the feeling that you’re not making any progress at all.
And if you ride with the bonnet on, you don’t feel the wind at all, but at most notice the influence of
gusts on your driving behaviour (see: How does wind make itself felt?).
Cold is no problem, because even in the depths of winter you can still ride with a T-shirt and thin trou-
sers (see: Which clothes?).
Precipitation is not a problem either, you don’t stay completely dry (on the contrary), but you don’t get
soaked to the skin by a downpour, and you don’t freeze either. A ride in the rain is not particularly ple-
asant, but it is not particularly daunting either (see: Can I ride in the rain?).
Ventilation is very important, at low temperatures because the windscreen fogs up, and at higher tem-
peratures because the cooling and drying effect of the airstream is almost completely absent. Even
with good ventilation you are actually always sweaty (see: What about ventilation?).
Small hills seem flatter because you can ride them with momentum for the most part (see: can I ride in
hilly countryside?).
Long hills seem steeper because, firstly, you are lugging more weight around, secondly, the power re-
quirement is high but the cooling is poor, and thirdly, you are spoilt by the other high speed (see: can I
ride in hilly countryside?).
Fast tyres are much more important because rolling resistance is a much bigger part (see: Why are
good tyres so important on a velomobile?).
Good grip is less important because velomobiles are multi-trackers – they don’t tip over immediately
when it’s slippery. You can risk slipping a bit instead of constantly riding like on raw eggs (see: Do you
need winter tyres or studs?).
Weight is more noticeable because air resistance, where weight is not a factor, is lower (see: Why are
velomobile riders so obsessed with low weight?).
You can deliver your power much more evenly because the losses are lower, i.e. you get back more of
the power you put in, e.g. you can accelerate before a climb and then ride it with more momentum, or
coast for an extremely long time after a descent. In the end, you have many more rolling phases than
with a normal bike.
How much luggage can I accommodate?
That depends very much on the respective velomobile. Basically bulky items are often problematic. But
otherwise the luggage volume is surprisingly large, even in the smallest velomobiles you can accommodate
at least as much as a touring bike can fit in two large saddlebags plus on the luggage rack. So touring is not
a problem at all. Larger velomobiles even have the same luggage volume as a smaller bicycle trailer, and
thus space for large purchases.
Can a trailer be used?
Basically yes, if it has a low drawbar. If you look at the back of the bodywork and it can be strengthened,
you can bolt on a standard trailer hitch. But this only makes sense in exceptional cases, because in the ve-
lomobile you can accommodate quite a lot of luggage, and a trailer is heavy, bulky, and significantly incre-
ases air resistance. So you can’t drive fast, and uphill you not only have to pull the weight of the trailer and
the load, but also the heavy velomobile. Therefore, it usually makes more sense to pull the trailer with a
normal bike.
Which clothes?
Similar to upright bikes but less. Even in deepest winter you can still drive with a T-shirt, then you have to
have warm clothes with you, otherwise a breakdown will quickly make you very cold. Overall, a thin shirt,
short or long trousers, and possibly a scarf or a neck warmer are usually sufficient. You can definitely leave
windbreakers, sleeves and gaiters at home.
Do you need click shoes?
Actually yes. Firstly, because on a recumbent bike the foot pushes on the pedal from behind instead of
from above i.e. it is not already pressed on the pedal by gravity. Second, because otherwise you can slip off
the pedal. While that on an upright bike often has only minor consequences, in the velomobile there is al-
most no space next to the feet – if the foot is not sitting correctly on the pedal, you bump into something,
and if you slip off while pedaling hard, you can even damage the bodywork on thin-walled velomobiles.
And thirdly, efficiency is also somewhat higher if you simply don’t have to worry about slipping, but can
always rely on a firm hold on the pedal.
How big is the turning circle?
About 10 meters, about the same as a car.
That sounds like a lot for a bike (it is too), but since you mainly drive on roads for cars, you almost never
have a problem in practice. On known routes you can often adjust to problem areas and make sufficient
swings in time, only on unknown routes and then typically on bike paths, it can happen that you
occasionally have to maneuver to get out of a trouble spot. But that happens too rarely to be a real
problem.
The exact turning circle depends on several factors:
Velomobil type: the narrower the wheel well, the larger the turning circle.
Velomobiles with closed wheel wells usually have a slightly larger turning circle.
Tyre width: the wider the tyre, the smaller the possible steering angle. First, the tyre hits the side of the
wheel well faster, second, the tyre is also taller and protrudes further forward / backward.
Wheel lacing: in velomobiles with closed wheel wells, the turning circle is smallest when the wheel is in
the cente of the wheel well. You can also dress up open wheel wells with so-called pants, this increases
the turning circle significantly and you have to countersteer on many curves beforehand.However, if
you re-spoke the wheels so that they no longer sit flush with the open wheel well, but in the middle of
the well, the turning circle is similar to that with open wheel wells.
How do you go backwards?
Bicycles usually do not have a reverse gear. You don’t normally need it either, because the turning circle is
small and otherwise you get off and push very quickly. Neither is the case with the velomobile, getting out
is more cumbersome, especially if you have to remove the hood or foam cover, and the turning circle is si-
milar to that of a car.
In a car, you need to go into reverse to park or to turn it several times. You don’t need the former with the
Velomobile: you just push it out of the parking space. And you rarely have to turn, especially not on fami-
liar routes. It may only be necessary on cycle paths with hairpin bends on a regular basis. But even then
you can often do without a reverse gear:
Hardly any street is really flat, and certainly not adjacent entrances, you can often drive uphill there,
let yourself roll back, and then get around the curve. A barely perceptible slope is sufficient for this.
With velomobiles with open wheel wells, you can at least do without getting out and turn the front
wheels with your hands like a wheelchair. But you get your hands dirty, and it only works on a really
flat roads, not uphill.
And then of course there are velomobiles with two foot holes where you can push back with the Fred
Flintstone technique.
What about ventilation?
In the velomobile you are shielded from the wind, i.e. if not driving during winter, the body needs cooling
– especially on the thorax and head. Another point is humidity, on the body this does not necessarily mat-
ter, but if it is too moist, you can irritate yourself in the crotch, for example. With the hood on it mists up
the windows at cool temperatures. With a fresh air supply you can blow away the humid air.
Most velomobiles have an air inlet at the front – this is the stagnation point where there is increased pres-
sure, so you can achieve a large air throughput with a small opening. In addition, a hole there does not dis-
turb the air flow along the body.
On some models there is also the headlight cut-out – this has the advantage that no further holes have to
be drilled in the bodywork, and the LEDs are well cooled by the wind, which increases efficiency. In return,
the headlamp sits quite low, and lighting of the road is correspondingly poor (only a small proportion is
scattered back).
In some Velomobile models, the bottom bracket mast is attached to the front of the air intake. This has the
advantage that the bottom bracket mast can also be supported from the front, and the air flows through
the mast backwards and the feet are not cooled by the cold fresh air.
If this cooling is not sufficient, you can also install a NACA duct duct usually in the front and in the top of
the bodyork (see: What is a NACA duct?).
Anyone who drives with a hood can also drive with a raised visor, a narrow opening is usually sufficient
there for sufficient air flow.
In addition, some drivers have drilled holes in the seat so that the back is better ventilated.
With all these measures, however, it is important that not only additional air is fed into the velomobile, but
that it can also flow out well (e.g. via vent holes at the rear) – otherwise an additional vent does not bring
additional air, but lowers the air flow through the other air intakes.
Can I ride in the rain?
Rain is not as annoying in a velomobile as on an open bike, but you don’t stay dry either. You are protected
from street dirt and splash water thanks to wheel wells and you are not soaked to the bone by a cloudburst,
but due to the high humidity inside, no sweat is removed, and a partly open visor or without a hood the
head and upper body get wet.
In addition, raindrops obstruct the view – regardless of whether you are driving with a hood or in converti-
ble mode with glasses. In the former case, it helps to have windshield wipers with which at least the large
drops can be distributed so that the view is tolerable.
While there are no real windshield wipers, at least the following solutions have proven their worth:
Magnetic wiper: Two elongated neodymium magnets, wrapped with absorbent material, stuck to-
gether on both sides of the pane. A viewing window can be wiped freely from the inside – that’s
enough because you sit close to the window and therefore don’t have to keep large areas clear. In addi-
tion, the magnets provide contact pressure so that even large snowflakes can be wiped away.
Wiper: There is also a manual windscreen wiper which is screwed into the visor; the elastic wiper arm
presses the wiper blade reliably against the double-curved visor.
Thread wiper: an elastic cord is stretched lengthways or across the visor and can be pulled back and
forth perpendicular to it with a second cord. This means that larger areas can be wiped than with a
magnetic wiper, but the contact pressure is lower.
Driving at night and in rain is still not fun, because first of all the oncoming drivers headlights reflect in
the raindrops on the windshield or your glasses, and secondly, the often low to the ground attached velo-
mobile headlights only dimly illuminate a wet road.
What to do against fogged up windows?
What is the cause of fogged windows? The driver sweats and the warm, moist air condenses on cold surfa-
ces, such as the windscreen.
The remedy is accordingly:
Insulate the pane so that it is not cold on the inside. That works for example with the Pinlock visor,
with which you can almost achieve double glazing.
Keep the moisture away from the window. You can do this by ventilating the velomobile well, if fresh
air flows in continuously from the front, the moist air is pushed out to the rear.
You can also open the visor a little, and place a small barrier in front of the lower edge of the visor,
which deflects the incoming air upwards, over the inside of the visor. This air film prevents the moist
indoor air from coming into contact with the visor.
And if none of this helps – for example because you are not moving and therefore have no air flow –
you have to wipe the inside of the window.
Then why is that not a problem in cars?
You sit passively in the car, so you don’t sweat. The humidity is correspondingly lower.
In the car you sit much further away from the windscreen. So you don’t breathe directly against the
window.
The interior of the car has a much larger volume. Even if you were sweating, it would take much longer
for all of the air to become damp.
The car has a heater. An internal combustion engine is inefficient, only about 20% of the energy goes
into the drive, the rest is heat – and with these thousands of Watts, the interior can be heated without
any problems, and fresh air can also be heated and directed to the window.
Is a velomobile suitable as a car replacement?
Depends. It is and remains a bike that only offers a slightly higher speed and range and a little better we-
ather protection. A car, on the other hand, is a “one size fits all”, you can take several people or large
amounts of luggage with you, drive hundreds of kilometers through very mountainous terrain, but also
only drive a short distance alone into town for shopping. A bicycle is of course significantly more restric-
ted. But that also means that a car is completely oversized for most everyday tasks, this can be done
excellently with the Velomobile. If this is the case on most days, you can do without a car – and still rent a
car that fits your needs for the few remaining transport tasks.
You can drive without being sweaty on arrival?
Difficult. Because inside the airflow is missing and you have to drive very slowly to avoid sweating down
your back. If you are not going uphill, a pedelec engine is not much help, because you practically always
drive faster than the maximum speed of the engine.
How does a velomobile drive in winter?
Not much differentfrom summer, you may need long trousers instead of shorts and a scarf against the
cold wind, and with a hood a Pinlock visor against fogging – but otherwise everything is like summer, you
can usually drive in a T-shirt (but you should have a warm jacket with you if you have to get out in the
event of a breakdown at freezing temperatures and tinker for longer).
In addition, good lighting is even more important in winter than in summer – because drivers expect fewer
cyclists in winter. Semi-puncture-proof tyres are also recommended, first, it’s not fun to have to patch a
flat in the dark and cold, and secondly, the cold also makes the rubber stiffer, so just changing the tyres be-
comes very tedious. However, the rolling resistance also increases noticeably in the cold – that’s why easy-
running tyres are not unimportant, especially in winter.
Do you need winter tyres or studs?
Not really, at least not on a flat route. Spikes on the front wheels prevent from slipping and shorten the
braking distance, and tread on the rear wheel ensures that the rear wheel is less likely to spin in snow. The
latter is actually only a problem when starting off and with steep climbs, so only in a few places. And since
a multi-track does not fall over on black ice, it is not worth installing spikes due to a few smooth bends –
spikes, like tread tyres, significantly increase rolling resistance so that high speeds can no longer be rea-
ched even on a straight road. It is better to drive carefully in curves and make slow steering movements,
and calculate that the velomobile can slip a bit – which is normally completely harmless. Only steep, win-
ding descents are critical on black ice, because then you may not be able to steer or brake. But as long as
you travel on cleared and clean streets, there are generally few problems – and if it is very slippery, then
the car traffic also slides.
How do people behave?
Basically, velomobiles are received very positively, there is almost exclusively positive interest or com-
ments – but you always draw everyone’s attention, more than with the most expensive automobile. It’s
rarely a problem on the go, children point at the velomobile, and drivers often drive slowly alongside, mar-
vel at the vehicle, crank down the window, make a comment and/or film or take pictures with their
smartphone.
Interest, however, can become a real problem when parking. People don’t just have to look at everything
up close or touch it carefully, damage is not uncommon. Children seem magical mirrors and other exposed
parts, it is not uncommon for the mirror to be twisted, maybe even broken off. If the velomobile was open,
footprints can be found inside because, for example, parents have put their children in without having
asked.
But it gets annoying when something breaks. Even if the Velomobile foam lid or the hood is closed, it can
be partially torn open violently, so that a Velcro strip on the foam lid was torn off or a crack appeared in
the carbon on the hood. It is simply incomprehensible how naturally some people tear off the foam lid as
they walk past so that they can take a look inside. But also the bodywork is at risk. Again and again there is
a crack in the carbon at the front because someone has obviously sat on it. While none of this affects
functionality and security, it is very annoying and also very expensive. So it’s best not to park the velomo-
bile where there are too many people with too much time and very bad manners.
How to lock and secure?
Like every bike: connect to a fixed object. Due to the lack of triangles, this is only possible on the rear
wheel – or on the stern handle or carrying eye, if present. While that’s not as good as a normal bike where
you can put a lock around the stable main frame – however, a velomobile is neither handy to steal nor in-
conspicuous, i.e. not for casual thieves. In addition, the removal of the rear wheel on some models requires
special knowledge, and sometimes also special tools.
There is a bigger problem – vandalism. The best remedy here is a tarpaulin in the most inconspicuous co-
lor possible – while an open velomobile attracts everyone’s attention, a covered vehicle is largely ignored.
How big does a storage room have to be?
See Fig. 30, here the dimensions of many velomobiles are recorded. The height is usually just under a me-
tre, and in terms of width, most velomobiles fit through normal doors.
Fig. 30 : Length and width of many velomobiles, the colour indicates the weight
– green is 20 kg, red is 40 kg. Note that the weight can vary greatly depending
on the equipment, and e.g. with the WAW, different front and rear sections are
available, so the length can be 269-301 cm. Leitra, Velayo and DuoQuest are out-
side the diagram.
Can I take a velomobile on the train?
In principle it is possible, but it is not without problems – velomobiles are large and bulky, unsuitable for
normal bicycle racks, and cannot be hung on hooks. So they can block half the bicycle compartment or the
boarding area, and the train employees then rightly refuse to take them along. In principle, you don’t have
a right to this, often even special bikes (tandems, cargo bikes) are not allowed in the conditions of carriage
– in the end, it’s always up to the discretion of the staff.
But with a few measures you can significantly increase the likelihood of being taken along:
Choose a route where you rarely have to change trains, and if you do, choose the transfer times very
generously.
Find out what type of carriage is used on the route. A bicycle compartment must be available, well-sui-
ted are, for example, double-decker carriages with a deep entrance or driving trailers with bicycle com-
partments, as these also have wide doors. Old carriages with narrow doors and steep stairs, on the
other hand, are unsuitable.
Do not board or disembark en route, but at the starting or terminus station. Then there is more time to
get on or off, and the train is not yet so full or is already a little emptier.
Arrive at the station early and be in the right place on the right platform.
If necessary, organise help in good time so that you do not take longer than other passengers to get on
or off the train.
Travel when there is little traffic. This means not during rush hour, but e.g. very early or late on wee-
kends or public holidays, or on routes with a lot of leisure cycling traffic, preferably in the off-season or
during the week.
Possibly buy two cycle tickets at the same time. This is not explicitly required, but avoids discussions if
you also need the space of two bicycles.
Take into account that the train may be surprisingly full and you have to take the next one.
Ultimately, there is no guarantee that you will find space on the train or that the conductor will take you.
But if you don’t cause any problems (don’t block a path, don’t cause delays, don’t disturb fellow passen-
gers, don’t make extra work for the staff and don’t violate any safety regulations) and are friendly, it
usually works out quite smoothly – then the railway employees have no reason to complain. And if you are
so quick that you have created a fait accompli before the staff can react, they usually don’t feel like starting
another unnecessary discussion afterwards.
https://cmoder.gitlab.io/velomobil-grundwissen/_images/vm-dimensions_en.svg
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Route selection
Can I ride in the mountains?
If you have a suitable gear ratio, this is no problem. But you need a different technique than on the upright
bike: do not pedal hard and out of the saddle, but crank uphill in a low gear – slowly but steadily.
Nevertheless, a velomobile shows its strengths especially in the lowlands:
Uphill aerodynamics have no advantages.
Downhill, the air resistance brakes much less, so the brakes overheat much faster (see Fig. 15).
The higher weight costs more power uphill (see Fig. 31)and puts more strain on the brakes downhill.
Uphill there isno cooling without a headwind, that makes mountain trips in the summer heat very
tedious.
Fig. 31 : Power demand at different gradients, the solid line is a velomobile, the
dashed line a road bike. As you can see, velomobiles are increasingly at a disad-
vantage at low speeds as the gradient increases – or rather, they have to go fas-
ter and faster as the gradient increases in order to have an advantage over a ra-
cing bike. While at a 1% gradient a velomobile is already at an advantage from
about 17 km/h and 100 W pedalling power, this point shifts to over 30 km/h and
over 500 W pedalling power at a 5% gradient. With 200 W pedalling power, on
the other hand, a velomobile is only as fast at a 4% gradient as a racing bike
would be at a 5% gradient.
Can I ride in hilly countryside?
In contrast to high hills, short hills work much more smoothly because, firstly, you can pedal with a lot of
power and/or a high output for a short time – it doesn’t matter so much if the gears aren’t suitable.
Secondly, the high speed of a velomobile means that you have a lot of kinetic energy (see Fig. 32) – so you
can take small hills in your stride without getting bogged down. This is called dolphining.
However, all this only applies to main roads that are designed for speedy riding. Pass roads in the high
mountains, for example, are surprisingly easy to cycle on because the gradient is very constant and the ro-
ads are very well adapted to the landscape profile. In contrast, in hilly country, especially on secondary ro-
ads, there are often also very steep (albeit short) sections that are poorly adapted to the landscape and that
you therefore cannot ride with constant power. A series of such climbs is often surprisingly exhausting –
with any bike, but especially with the velomobile it makes itself felt negatively if you can’t take advantage
of any momentum.
https://cmoder.gitlab.io/velomobil-grundwissen/_images/speed_vs_power_uphill_en.svg
https://cmoder.gitlab.io/velomobil-grundwissen/_images/speed_vs_power_uphill_en.svg
Fig. 32 : Conversion of kinetic energy into altitude metres. So at speed 50 you
have enough energy to roll up a hill about 9 m high. On the one hand, you have
to subtract the driving resistance from this, on the other hand you can pedal
along. So the exact balance then depends on the gradient, for steep hills the dia-
gram is quite correct, while on a flat hill you can pedal along for longer and thus
get higher.
Fig. 33 : Map of maximum gradients (= total differential of topography) and ve-
lomobile riders (from data provided by Velomobiel and InterCityBike and mem-
bers of the Velomobile Forum). It can be seen that only in the Alps and parts of
the low mountain ranges there are steep gradients, e.g. the foothills of the Alps
and the southwestern German strata are rather flat, except for the northwestern
sides (e.g. Albtrauf) and deeply cut valleys (e.g. Jagst, Kocher, Altmühl).
Accordingly, velomobile riders can also be found in the hilly country – the distri-
bution corresponds more to population density than topography.
Can I ride on bike paths?
Good question – the quality of bike paths is far too different to make a general statement about it, but the
following generally applies:
Cycle paths are not designed for velomobile speeds, even with a racing bike you reach your limits.
Cycle paths often have tight curves and are very confusing, even if you could sometimes drive fast, you
would often have to brake.
Junctions are often confusing and blocked by stopped cars and cyclists are not often given the right of
way.
Cycle paths are often narrow, so that other cyclists can hardly be overtaken.
Cycle paths often have obstacles such as jostle bars or hairpin bends that cannot be passed with a
velomobile.
Roots and other bumps are particularly uncomfortable with a multi-track with a tight chassis.
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That is why it is usually not only more comfortable, but above all much safer to drive on the road. But
there are also good, wide and clear inter-country cycle paths that can be used perfectly by a velomobile.
However, you cannot rely on a minimum standard.
Can I drive on unpaved roads?
Walking speed does it, but it’s not fun. As mentioned, the rolling resistance plays a major role in the velo-
mobile, this is much higher on unpaved roads, and accordingly you are much slower. In addition, a velo-
mobile typically has narrow, hard-inflated tyres and a tight chassis, which makes driving less comfortable.
A multi-track not only hops up and down, but also tilts around the longitudinal axis. And since a velomo-
bile is a wonderful sound box, it rattles and booms quite well.
How about driving in city traffic?
In principle, you can also ride well in the city, however, a velomobile has hardly any advantages there.
The main advantage is speed, but since the acceleration distances are long (see Fig. 34) and you have to
stop frequently in the city, you hardly reach a high speed. However, this does not mean that velomobiles
are slower than other bicycles there – the acceleration is very similar, but the high final speed is only achi-
evable if you can let it run for kilometres. In the city, a velomobile is therefore permanently in the accelera-
tion or coasting phase.
As velomobiles are not that manoeuvrable, many cycle paths are unsuitable, either impassable because of
obstacles, or too narrow to overtake other cyclists, or too confusing for higher speeds (see: Can I ride on
bike paths?). The recumbent position is practically irrelevant: because the head is further back, you can
see junctions later – but it is only a matter of fractions of a second, at higher speeds this time becomes
shorter and shorter, but the braking distance longer and longer. Therefore, unclear cycle paths brake all
bicycles to a similar speed, with the velomobile, only the difference to the normal cruising speed is greater.
On the road, on the other hand, heavy traffic is often a problem, there you are stuck in traffic jams with the
cars. On major thoroughfares, however, you can definitely benefit from a “green wave” for which you
would be too slow with a normal bicycle.
Fig. 34 : Time and distance to reach 90% and 99% of the final speed with 300 W
pedalling power. Both increase strongly with speed, that is why the acceleration
phases are so long in the velomobile. In the lower speed range, all bicycles acce-
lerate similarly well, a velomobile is minimally slower due to its higher mass and
drive losses (upper diagram), but has made up for this shortfall at a good 30
km/h. The velomobile’s acceleration is also slower in the lower speed range. This
is hardly noticeable in the acceleration section (lower diagram). After about half
the time and a third of the distance, you are already close to the final speed,
further acceleration is very slow.
How does it work on short distances?
A velomobile is rather unsuitable for short distances. The higher speed does not save any significant time,
the weather protection is less important (you can hardly cool down in a few minutes, you can better close a
gap between rain fronts), getting in and out takes longer, and you cannot carry a backpack, you have to
Stow luggage and take it out again.
How does it go on long distances?
Outstanding. This is where the strengths of a velomobile come into play: great time savings thanks to high
average speeds, good weather protection, large luggage capacity, no seat problems, no numb hands, no
neck pain.
Are velomobiles only suitable for rural areas?
Rural areas with lots of open space and little traffic should be ideal for velomobiles, at least if the
topography plays along (see Fig. 33). However, in Fig. 35 youcan see that most velomobile owners do live
in densely populated areas, maybe not necessarily in the middle of big cities, but at least on their outskirts
or in the suburbs.
https://cmoder.gitlab.io/velomobil-grundwissen/_images/speed_vs_time_distance_300W_en.svg
https://cmoder.gitlab.io/velomobil-grundwissen/_images/speed_vs_time_distance_300W_en.svg
Fig. 35 : Velomobile users and population density (Eurostat, population density
2019 by NUTS 3 regions).
How do you drive as energy-efficiently as possible?
By not braking.
You can’t do anything about drive losses, rolling resistance and air resistance while driving, because they
are always there. Or, by keeping your speed as constant as possible, you can reduce air resistance, which
increases disproportionately with speed (see: How to achieve the highest possible average speed?). You
get the energy from climbing back on a descent, the acceleration power when coasting (or by rolling uphill
with momentum), but everything that is braked away is lost and has to be laboriously built up again.
The first thing that helps against this is a good route planning, so that you don’t have to brake if possible,
and if you do, then let it roll as early as possible – you get surprisingly far, see Fig. 36.
Fig. 36 : Conversion of kinetic energy to rolling distance for different types of
bicycles
How to plan a route for the velomobile?
If you want to travel as quickly and relaxed as possible, you have to be able to drive at a constant speed.
That means:
clear thoroughfares instead of winding alleys or residential streets
Priority roads or roundabouts instead of stop signs
as few gradients as possible
Descents should be as flat as possible so that you don’t have to brake, but can always pedal along
You can tend to look at online route planners for cars instead of bicycles, the latter mostly lead over low-
traffic routes, but are often very winding. In contrast you don’t need a high maximum speed, but as few
braking operations as possible – each acceleration not only costs a lot of power, but also several 100 me-
https://cmoder.gitlab.io/velomobil-grundwissen/_images/map_velomobile-users_population-density.svg
https://cmoder.gitlab.io/velomobil-grundwissen/_images/map_velomobile-users_population-density.svg
https://cmoder.gitlab.io/velomobil-grundwissen/canIrideonhills?
https://cmoder.gitlab.io/velomobil-grundwissen/canIrideonhills?
https://cmoder.gitlab.io/velomobil-grundwissen/Howdoyouplanarouteforvelomobiles?
https://cmoder.gitlab.io/velomobil-grundwissen/_images/speed_vs_rolling-distance_en.svg
https://cmoder.gitlab.io/velomobil-grundwissen/_images/speed_vs_rolling-distance_en.svg
ters of distance, so that with frequent traffic lights you never get to high speed, but still exhaust yourself. It
is better to choose a route where you can not drive quite as fast, but instead smoothly – instead of a single
braking process that ruins the speed over several hundred meters.
BRouter is recommended as a route planner, this has, among other things, a routing profile for velomobi-
les and is completely configurable. The data comes from Openstreetmap, incorrect routing is therefore
usually caused by incorrectly entered or incomplete Open Street map data. Fortunately, everyone can cor-
rect this themselves, until the changed data arrives in BRouter, however, it will take some time. The as-
sumptions made by BRouter have generally proven themselves, however, they can be inappropriate in cer-
tain areas or in other countries.
If you want to plan the route by hand, you can still use the BRouter velomobile profile as a guide. This con-
verts all obstacles into detours, For example, the specification uphillcost = 80 from the profile file means
that one vertical meter uphill corresponds to a detour of 80 meters, and turncost = 150 means that a right-
angled branch corresponds to a 150m detour.
Commuting
Is a velomobile suitable for commuting?
Depends on, for example, if you want to travel to work in less than an hour, you can travel up to 30 km in
the lowlands – correspondingly less with mountains. Depending on the route, the velomobile is a few mi-
nutes faster than an upright bike, but above all much more comfortable (since it is less worth driving at full
throttle everywhere), you can take more luggage with you and is also less dependent on the weather – the
clothes are almost the same summer or winter, and even a cloudburst doesn’t get you completely soaked,
you can continue driving.
You should always have a change clothes with you – unless the route is very short. Ideally, you can then
take a shower at the workplace, otherwise you can get by with a reduced “cat wash”.
Which distance can be covered daily?
This depends a lot on the particular route, but the lists at Velomobiel.nl and Intercitybike can give a rough
idea. Entering the kilometers is voluntary and not always up-to-date, but one can assume at least for larger
mileages that it was not a short vacation trip, but that the kilometers have accumulated over several
months. This gives fig_rijderslijst_dist, here one can see that faster velomobiles tend to be used for
slightly larger distances.
Fig. 37 : Monthly travel distances of velomobiles from the manufacturers
Velomobiel.nl and Intercitybike. Data entry is voluntary and thus not represen-
tative. Only velomobiles with a total mileage of at least 7500 km have been eva-
luated (as of: 02/2020).
Do you need a motor for a long commute?
To make the driving time on a long route bearable, it is often desired to install a motor. Whether this ma-
kes sense, however, depends very much on the route and the motor (see Motor yes or no?). Although a 45-
km/h motor reduces the riding time in almost all cases, it is not so easy legally, at least in Germany – only
a few models are even permitted and cycle paths may not be used (see Legal situation in Germany). A 25
km/h motor, on the other hand, is legally quite unproblematic. However, you usually ride a velomobile
above 25 km/h, where the motor is of no use. Therefore, such a motor is only useful on long climbs, where
you can save a lot of time. On frequent accelerations, a motor also helps, but only saves power – you don’t
accelerate significantly faster, and accordingly you save almost no time.
Do you need a fast velomobile for a long commute?
Beginners looking for an all-weather bike for a longer commute are often advised to buy a fast velomobile
– but these are very expensive new and hard to get second-hand. Beginners, on the other hand, rarely want
to spend that kind of money and don’t intend to set speed records. Who is right?
The top speed is actually not that relevant in everyday life, and compared to normal bicycles, the
aerodynamics of “slow” velomobiles are still excellent. In contrast, velomobiles trimmed for maximum
speed often have other disadvantages, such as a very large turning circle, small suspension travel and low
ground clearance, which makes them impractical to unsuitable for some routes. Moreover, even at high
speeds, air resistance only accounts for a good half of the drag, and even less at the median speed in
everyday life (see Fig. 23) – so it is hardly worthwhile to put a lot of money and effort into the final optimi-
sation here.
But fast velomobiles not only have very good aerodynamics, they are also particularly efficient – i.e. they
are relatively light and have a stiff drivetrain. You also benefit from both at low speeds: a low weight is not
only beneficial uphill (more so than on normal bikes, see: Why are velomobile riders so obsessed with low
weight?), but also reduces rolling resistance (see: Why are good tyres so important on a velomobile?) and
kinetic energy (see: Why are the acceleration phases so long in a velomobile?). And a stiff drivetrain ma-
kes powerful acceleration more efficient, as needed when accelerating or going uphill (see: Why a stiff
drivetrain?).
http://www.velomobiel.nl/rijderslijst/index.php?amount=0
https://www.intercitybike.nl/rijderslijst/index.php?amount=0https://cmoder.gitlab.io/velomobil-grundwissen/_images/rijderslijst_dist-histogram_en.svg
https://cmoder.gitlab.io/velomobil-grundwissen/_images/rijderslijst_dist-histogram_en.svg
This means that on long and mountainous routes it is worthwhile to have a velomobile that is light and has
a stiff drivetrain.
Repair and maintenance
Do you need a special workshop?
Not really. Velomobile technology is not rocket science, basically most things are easy to master with a lit-
tle basic knowledge of bicycle technology. And since the vast majority of components come from the nor-
mal bicycle sector, a bicycle workshop should have no problem with most things. You don’t have to be a
hobby mechanic to drive a velomobile. The fact that there are many velomobile drivers who are is probably
due to their interest in bicycles and bicycle technology, and secondly, they often do high mileages and the-
refore save a lot of time/money if they can do routine work themselves.
Manufacturer support is only required for comparatively few defects, but even special parts (e.g. struts)
are usually sent quickly and are easy to install. And if you have bought a somewhat older velomobile model
whose teething troubles have now been eliminated, you should be able to do many tens of thousands of ki-
lometers without any velomobile-specific spare parts.
However, the Velomobile is definitely more difficult for troubleshooting because many parts are difficult to
see and you cannot turn the crank with one hand and watch the rear derailleur. It is therefore a thankless
task to find the cause of some symptoms. A velomobile driver should therefore keep an eye and both ears
open when something feels or sounds different and get to the bottom of things as soon as possible.
Wear parts, in contrast to normal bikes?
Basically, there is less wear and tear on the velomobile, the drive train in particular is very durable because
it is protected from dirt. The chain lasts a very long time because the wear is also distributed over a much
greater length. Also drum brake pads are very durable – not because they are not used very much, but be-
cause they are quite oversized. The short-lived parts are usually the tyres.
What are common maintenance tasks?
Most likely: check air pressure, inflate tyres, and examine the tyres (especially on the rear wheel) for da-
mage (stones, cuts, damage to the carcass). And of course charge the light battery.
Occasionally the chain must be wiped and oiled and the brakes adjusted. If the latter no longer resets
properly, you can place shims on the brakes (see What is it about placing shims on drum brakes?), Or re-
place the brake pads completely. And if necessary, the braking and Shift cables can be changed. And if the
chain tubes are dirty, you put a thin piece of fabric around the chain and pull it gently through the tubes.
How long does carbon fiber last? How can I protect it?
Carbon fibers do not age, just the epoxy resin under the effects of UV light. But that’s just a cosmetic pro-
blem, if the top layer of resin changes color or decomposes, you can grind it down and apply a new thin
layer of resin. A UV resistant lacquer, Gelcoat or Film can protect the epoxy resin.
How to repair carbon?
By gluing a patch over the breakage with epoxy. Important here is the :term:` Scarfing `,
around the broken point the material is beveled in a V-shape and filled with several patches of increasing
length. Firstly, this increases the adhesive surface and secondly, the overall thickness remains constant,
which means that there are no stress peaks at the transitions; the respective edges of patches and original
material are thin and therefore flexible and adapt to deformations of the other side instead of seperating.
Since carbon fibers can only absorb tensile forces (see: `Why are velomobiles made of carbon or glass fi-
ber?`_), the fibers of the patches must be aligned in the direction of the tensile forces and lie as flat as pos-
sible. A well-made carbon repair is neither heavier nor less strong than the original material.
What is twill? What is a roving?
A carbon fibre is only a few micrometres thin, that is why fibre bundles of several thousand fibres are
usually used. This is called roving.
In order to be able to produce flat components from the fibres, they are usually woven into a fabric. Vari-
ous weave types are possible here. In plain weave, a weft thread runs alternately over and under a warp th-
read, shifted by one warp thread for each weft thread. This results in a quite strong fabric, but it is difficult
to drape over curved shapes. For this reason, the twill weave is usually used for carbon, here the threads
cross over less frequently than in the plain weave, which makes for better drapeability, and also for the
typical carbon look.
In a woven fabric, the rovings support each other through the crossing points, this reduces the sensitivity
to puncture stresses. This is why carbon fabric (with its typical carbon look) is usually used on the surface
of components. In contrast, uni- or bi-directional fibres are often used in deeper layers of a heavily loaded
component. Since these are not interwoven, the fibres lie straight instead of wavy, which provides more
stiffness – under tensile load, the fibres are not first pulled straight, but already are.
Why shouldn’t aluminum parts be glued directly on
carbon?
Because of the electrochemical voltage effect. Both carbon and aluminum conduct electricity and there is
also sufficient moisture in the velomobile, Carbon has an electrochemical potential of +0.75 V (compared
to the normal hydrogen electrode), aluminum of -1.66 V – making aluminum the less noble material. If a
current can flow between the two materials, it beccomes contact corrosion, Carbon serves as the cathode
and aluminum as the anode, it is oxidized to aluminum oxide – it slowly dissolves.
Epoxy resin has an insulating effect, but, for example, at holes there is a direct connection between carbon
and aluminum. It is therefore advisable to place a thin layer of glass fiber fabric around the metal that iso-
lates it from the carbon.
How can the Velomobile body be decorated?
Three methods have been established:
Gelcoat: This is a colored synthetic resin, which is incorporated into the mold during construction.
Only a few colors are possible here, and only single-color components.
Painting: the finished velomobile is painted, this means more colors are possible and, by masking, the
combination of several colors. In addition, the layer tends to be thinner (approx. 0.08 mm) and there-
fore lighter (approx. 200 g / m²).
Filming: vynil film offers the most design options and requires the least equipment to achieve a good
result. The thickness (approx. 0.09 mm) is comparable to lacquer, but tends to be lighter. Compared to
a car, however, velomobile filming is relatively expensive because there are many curved surfaces.
Safety
How is a velomobile perceived by drivers?
Basically, you are treated more like a car than a cyclist. This also means that you usually have more side
passing distance, and are rarely referred to take the bike path.
However, speed is often underestimated, it often happens that you are slowed down by drivers who want
to pass the bike too quickly, or that overtaking drivers need a lot more distance and are close to oncoming
traffic or another constrictions.
In addition, overtaking is often prohibited in oncoming traffic, Here you have to react appropriately and
just close the lane in dangerous places.
Visibility?
A velomobile in itself is definitely not inconspicuous or invisible, and if a still don’t see it, you should con-
sider whether he is fit for public road traffic.
Nevertheless, there are weak points, for example, the narrow and low silhouette is difficult to see,
especially in difficult lighting conditions. Good lighting helps here especially daytime running lights. The
second main problem is likely to be selective perception – cyclists are often not expected,on the other hand, has enough space because behind the head of the driver the vehicle is
high anyway (exception: four-wheeler ). A large bike wheel has
slightly lower rolling resistance, and secondly, it transfers the pedaling force of the driver to the road over
a longer distance (larger circumference) than with a small rear wheel, there the wheel needs to turn faster
for the same speed, so the chainring should have about 100 teeth or you will need an intermediate gear
box. Small rear wheels do provide more torque for climbing steep hills.
Why is the drive wheel usually in the rear?
Because the steering is in front. It would be very cumbersome to drive a steered wheel because you would
have to steer the chain somehow. Driving both front wheels would require, for example, a cardan shaft and
a differential, and there is no space for this because the driver sits between the wheels. It is therefore the
lesser evil to run a long chain to the back wheel, the two idler pulleys under the seat only take up a few cen-
timeters extra height.
Why a velomobile with four wheels?
A four-wheeler is a velomobile that has two rear wheels instead of one. In order to not have to make the
hood extremely wide, small wheels are used as rear wheels so that you can place them closer to the cente of
gravity.
Four-wheelers have a few advantages:
The tipping stability is higher.
There is a larger luggage compartment between the rear wheels under the hood which can accommo-
date bulky items.
The rear breaks out less easily because, firstly, two wheels are hardly ever in the air at the same time,
and, for other reasons they don’t both lose grip at the same time (see: Why is it dangerous when the
rear wheel slides?) And secondly the rear wheels are closer to the cente of gravity so that they carry
more weight.
If both rear wheels are driven then traction is better, also because they carry more load. For the same
reason, a single driven small rear wheel is only slightly worse than a large driven rear wheel on a
tricycle.
You have four tyres of the same size, so you only have to take one spare tube and tyre with you.
But there are also disadvantages:
An additional wheel with an additional or larger swing arm means more weight.
Two driven rear wheels are problematic when cornering if you use a rigid axle, they will wash out in
curves. You can solve this with a differential, but this in turn means more weight and complexity and
causes additional drive losses.
If you only drive one rear wheel, the traction is less than with a tricycle.
A small drive wheel needs a higher gear ratio, an intermediate gearbox may be necessary, which in
turn means more weight.
The chain runs in the middle, but the drive wheel is on the side so you need a heavy, torsionally stiff
axle.
Small wheels have higher rolling resistance.
Why is a four-wheeler more stable?
Tipping stability is determined by how wide the vehicle is and how low the centre of gravity is. A four-whe-
eler is no wider than a three-wheeler, the centre of gravity is the same height, and the tipping line (i.e. the
line connecting the front wheel and the rear wheel on the side of tipping) is hardly further away from the
centre of gravity, namely only at the rear – but the centre of gravity is closer to the front wheels than to the
rear wheel. Why is a four-wheeler nevertheless noticeably more stable against tipping?
Firstly, the position of the centre of gravity relative to the tipping line determines the balance:
If the centre of gravity is above the tipping line, the equilibrium is unstable – any shift of the centre of
gravity across the tipping line lowers it, i.e. it tips to one side or the other.
If, on the other hand, the centre of gravity is next to the tipping line, the equilibrium is stable – in or-
der to cross the tipping line, the centre of gravity must first be raised.
The wider the vehicle, the higher the centre of gravity must be raised to cross the tipping line.
The lower the centre of gravity, the steeper it must be lifted initially, the lifting corresponds to the co-
sine of the angle – first it goes upwards, then increasingly to the side. I.e. a low centre of gravity not
only has to be lifted higher when tilting, but the lifting is also steeper at the beginning.
This means that a multitrack is stable because the centre of gravity is located on the inside between the tip-
ping lines and thus has to be lifted first when tipping. With a three-wheeler, however, this only applies to
the front wheels – the rear wheel is in the middle of the vehicle, and the mass there is above its point of
contact, so the three-wheeler is in an unstable equilibrium at the rear wheel. On a four-wheeler, on the
other hand, the mass is in stable equilibrium along its entire length.
Secondly, there is the suspension. A vehicle with suspension does not tilt immediately, but before that the
wheels spring up or down – the centrifugal force is not compensated by the lifting of the centre of gravity,
but by the spring force of the chassis. This causes the body to rotate around the longitudinal axis between
the wheels. However, this only works with the wheels on the outside – in the case of a three-wheeler, this
means only the front wheels, while the rear wheel continues to tilt over its point of contact. With a four-
wheeler, on the other hand, all four wheels can compress in the curve before the vehicle starts to tip – the
front wheels then do not have to counteract the roll alone, so their suspension can be softer. In addition,
with a four-wheeler, the rear suspension can be designed so that the centre of roll during compression is
higher up compared to an independent suspension (as with the front wheels) – so the roll axis is not at
road level as with the rear wheel of the three-wheeler, but closer to the centre of gravity, which makes the
vehicle roll less.
And thirdly, a four-wheeler is wider at the rear, which means that the luggage there does not have to be
stacked as high, which brings the centre of gravity further down, moreover, the luggage there is next to the
tipping line instead of above it.
Open or closed wheel wells?
Both have advantages and disadvantages:
Closed wheel wells are slightly better aerodynamically.
With closed wheel wells it doesn’t matter aerodynamically how far inside the wheel sits, with open
wheel wells, it must be as flush as possible on the outside, i.e. the adjustment is more flexible.
Closed wheel wells are often slightly larger, so wider tyres can be used (these are also correspondingly
taller). With open wheel wells, on the other hand, you try not to make them as large because the gap
between the wheel and bodywork disturbs airflow.
Velomobiles with closed wheel wells are not necessarily wider, which means that they have a smaller
track width and are therefore somewhat more sensitive to tipping.
And of course, with open wheel wells, removing and installing the wheels and adjusting the brakes is
much easier. However, there are now velomobiles with closed wheel wells, where you can access the
axles from outside via maintenance hatches, there at least the removal and installation of the wheels is
similarly simple.
One-sided or two-sided swing arm?
A double-sided swing arm is the classic design, normal rear hubs fit. Special hubs are required for one-
sided swingarms.
Wheel hub motors are only available with two-sided mounting (except for one direct drive model from
Canada). With one-sided swingarms you can only easily install a bottom bracket motor.
In the case of a double-sided swing arm, the forces act on the cente, this makes torsion significantly
lower. A one-sided swingarm must be built much more solid to be similarly torsionally rigid.
With a one-sided swingarm, you can change the tyre without having to remove the wheel.
With a one-sided swingarm there is more space on the left side of the wheel arch for baggage. There is
less space on the right-hand side because the swing arm is much moreleast of all to be
fast, and also not in bad weather. To change that, more people would have to cycle.
How to behave in traffic?
As usual: with foresigh, confidence, calm.
However, a particular danger is waiting behind stopped cars without being visible in their mirrors. Many
SUV-like cars only have very high and small rear windows, so you should keep a good distance to be visible
from the inside mirror. In addition, a velomobile is too narrow to be seen from the side mirrors if you are
not exactly offset to the side of the car. Many cars have reversing sensors, but these are often mounted
quite high, so that a velomobile may not be reliably recognized.
What is the risk of injury when an accident?
Solo accidents are generally less common in multi-lane vehicles because it is not so easy to tip over, when
it’s slippery you slide a bit, but usually nothing else happens.
In a collision a velomobile has neither the stability nor the mass of a car in order to counter it with so-
mething worth mentioning. Nevertheless, many accidents have gone surprisingly lightly so far for the fol-
lowing reasons:
Protection by the bodywork: the velomobile slides on its body over the asphalt instead of the driver
with his bare skin – even if the bodywork is damaged by a collision.
Lying position: in the event of a frontal impact, the legs are affected first, however, these can withstand
high forces quite well, in contrast to the head or arms that often contact first on an upright bike.
Shape: the convex shape of the body prevents the bike from sliding under the car and being overrun.
This is why injuries often arise primarily from sharp objects in the interior, such as screws, handlebars,
brake and shift levers, or from a collision of the head and upper body with the coaming or the inside of the
hood.
However, there have also been some serious accidents, in these, the driver has either been thrown out of
the velomobile or has collided with an object (e.g. stone, post). For this reason, some velomobiles have a
cockpit hatch that is as small as possible, which is not only aerodynamically favorable, but (especially if it
tapers to the rear) fixes the body at the shoulders. Since the rear hood is usually higher than the head, it
acts as a roll bar – if the driver sits far enough back. A shoulder strap would also help here.
In contrast, a hood is usually not so stiff and firm that it can withstand high forces. But above all, it is only
fastened with rubber tensioners, so that it could fly away under greater force. At least it should direct ob-
jects past the head and prevent skin contact with the asphalt.
Fear is relatively widespread that a sharp-edged carbon splinter will result in a crash. But this is largely
unfounded, the carbon shell is so thin that it tears quickly and hardly produces splinters. In addition, mo-
dern velomobiles have a nylon liner that largely prevents the cover from tearing, some carbon fibers break,
but remain in place. A danger would only arise if very massive and stiff carbon parts were pulverized by
the collision, but in such a violent accident, you have completely different problems than a few splinters of
carbon in your skin.
Because of the roll bar function of the scoop and the lower risk of self inflicted accident, there are
significantly fewer reasons for one to wear a helmet, in addition, many do not fit under the hood or are too
long at the back. In addition, the face would still be unprotected.
Legal
Status: 08/2022
Legal situation in Germany
From a legal point of view, a velomobile is clearly a bicycle - it does not require registration, vehicle tax or
insurance, but the obligation to use the cycle path applies. An exception is an S-Pedelec; this must be ap-
proved by the manufacturer, requires an insurance number and may not be used on cycle paths.
In practice, however, some regulations for velomobiles do not make sense. Firstly, this concerns the obli-
gation to use the cycle path (StVO § 2 Para. 4); However, cycle paths are rarely suitable for velomobile
speeds and often have too small curve radii and chicanes such as side gates. On the one hand, there is an
obligation to use it, but at the same time there are structural measures that make use impossible. And then
there are things like blind spots, parked cars, inattentive pedestrians and cyclists, poor surface quality.
Even if such a mandatory cycle path could be used by a velomobile, it is often much safer to use the lane –
especially in urban areas, where you drive at about the same speed as cars, but the cycle paths are often
very difficult to see from exits and junctions.
http://www.gesetze-im-internet.de/stvo_2013/__2.html
https://cmoder.gitlab.io/velomobil-grundwissen/_images/StVO_Zeichen_237-240-241.svg
https://cmoder.gitlab.io/velomobil-grundwissen/_images/StVO_Zeichen_237-240-241.svg
Fig. 38 : Compulsory cycle lanes: signs 237, 240 and 241
In particular, the statements of the Road Traffic Regulations on cycle paths are specified in the General
Administrative Regulation on Road Traffic Regulations (VwV-StVO) (e.g. with minimum dimensions);
The following paragraph is particularly interesting for velomobiles:
The specified dimensions for the clear width refer to a single-track bicycle. Other bicycles (cf. defini-
tion of the Road Traffic Convention of November 8, 1968, Federal Law Gazette 1977 II p. 809) such
as multi-track cargo bicycles and bicycles with trailers are not included. As a rule, the drivers of
other bicycles should not be objected to if the use of the cycle path is unreasonable under the circums-
tances of the individual case if they do not use the cycle path.
– VwV-StVO 2017, paragraph 23
The mentioned definition of a bicycle can also be found in StVZO § 63a Abs. 1 again, Pedelecs added in pa-
ragraph 2.
The second point is the bicycle lighting (StVZO § 67):
Headlight: Many velomobile models do not meet the minimum mounting height of 400 mm.
Rear light: Foreign manufacturers rarely install rear lights with a German test mark. Individual LEDs
or LED strips are often integrated directly into the rear, and commercially available rear lights with
test marks are not suitable for integration into a body.
Reflector: Is also almost never available. Some manufacturers install a retro-reflective film on the rear,
which is just as good in itself, but does not have a test mark.
Indicators: These have only been permitted since 2017; and accordingly there are practically no bicycle
turn signals with type approval on the market. Since it is difficult to show the direction with your
hands on velomobiles, turn signals are almost always installed, but they often have no test marks.
Spoke reflectors: These would be mandatory, but practically never exist, and at least with the wheel ar-
ches closed, they are also completely pointless. Only reflective strips on tires in open wheel arches are
possible without any problems and also make sense.
Pedal reflectors: Are also completely pointless and therefore practically never available.
The bicycle lighting is regulated in a separate paragraph of the StVZO, but not the type approval of the
lighting. Therefore, with a velomobile you are not limited to bicycle lights, but can also, for example,
install components for motorcycles. This is particularly interesting for turn signals, because they
hardly exist in bicycle accessories.
It is therefore very difficult to combine safety and legal compliance in a velomobile. You are in a legal gray
area; Much is tolerated in practice or is even stipulated in the VwV-StVO, but there is no legal certainty.
On the other hand, the regulations on the maximum speed in StVO § 3. For the most part, these only apply
to motor vehicles, i.e. cyclists in particular do not have to observe the limit of 50 km/h in built-up areas.
Legal situation in Austria
In Austria, the Road Traffic Act (StVO) 1960 and the Bicycle Ordinance (FVO). The relevant statements
there for velomobiles are:
For correspondingly signposted cycle lanes (StVO§52), there is a general obligation to use cycle paths.
However, this only applies to single-track bicycles with a wheelbase of up to 1.7 m.
Racing bikes on a training ride, multi-track bikes and bikes with trailers may use both the roadway and
the bike path if they are no more than 1 m wide. Wider vehicles must always be on the road. (A bicycle
with a maximum weight of 12 kg, a rim diameter of at least 630 mm and a maximum rim width of 23
mm is considered a racing bike.)
Unlike in Germany, there are separate signs for cycle paths that are not required to be used (= square
signs).
Cycle paths may generally be used in both directions, unless one direction is indicated by directional
arrows.
Cycle paths may also be used by roller skaters.
Cycle streets may be used at a maximum of 30 km/h (StVO §67).
Helmets are compulsory for children under the age of 12 (StVO §68).
Headlights: Only a white continuous light with at least 100 cd light intensity is required, but no mini-
mum mounting height or approval (FVO §1).
Rear light: Here, too, only a minimum light intensity of 1 cd is required (FVO §1).
Front and rear reflectors (white or red) as well as yellow spoke reflectors (or reflective tires) and pedal
reflectors are required (FVO §1). Hardly any velomobile can fulfill this.
Multi-lane vehicles need two rear lights and reflectors at the same height (FVO §2). Only a few velo-
mobiles fulfill this.
The brakes must act on all wheels (FVO §2). Almost no velomobile does this – the rear wheel is usually
unbraked, and with good reason (see: Why no brake on the rear wheel?).
There must be a bell/horn (FVO §1).
If a bicycle trailer is towed, the bicycle must have a stand (FVO §3). This is obviously pointless with a
multi-tracker.
Legal situation in Switzerland
In Switzerland, traffic is regulated by the Road Traffic Act (SVG), the Traffic Rules Ordinance (VRV) and
the Ordinance on the Technical Requirements for Road Vehicles (VTS). The rules relevant to cyclists are:
Bicycles are vehicles with at least two wheels that are moved exclusively by muscle power (VTS Art.
24).
Bikes with motor support up to 25 km/h and a maximum of 0.5 kW (= correspond to pedelecs) are cal-
led light motorbikes; in principle, the same rules apply to them as to non-motorised bicycles. On the
other hand, higher motorized bicycles (up to 45 km/h, up to 1 kW electric or 50 cm3 cubic capacity;
correspond to S-Pedelecs), called motorcycles, are in some respects more equal to light motorcycles
(e.g. Helmet obligation, insurance vignette, lighting regulations) (VTS Art. 18).
In contrast to bicycles and light mopeds, mopeds are basically single-track (VTS Art. 18); as three-
wheeled vehicles, on the other hand, they count as small motorcycles (VTS Art. 14), with four wheels
as light motor vehicles (VTS Art. 15).
Children under the age of 6 may only cycle on main roads with a supervisor (from the age of 16) (SVG
Art. 19).
Persons who are unfit to drive can be prohibited from cycling (SVG Art. 19).
Sidewalks, footpaths and hiking trails may not be used by bicycles unless expressly permitted (SVG
Art. 43).
Cycle paths and cycle lanes must be used (SVG Art. 46).
http://www.verwaltungsverbindungen-im-internet.de/bsvwvbund_26012001_S3236420014.htm
https://dejure.org/ext/a63942972b2d9b3a5f6937aa5e69f835
http://www.gesetze-im-internet.de/stvzo_2012/__63a.html
http://www.gesetze-im-internet.de/stvzo_2012/__67.html
http://www.gesetze-im-internet.de/stvo_2013/__3.html
https://www.ris.bka.gv.at/GeltendeFassung.wxe?Abfrage=Bundesnormen&Gesetzesnummer=10011336
https://www.ris.bka.gv.at/GeltendeFassung.wxe?Abfrage=Bundesnormen&Gesetzesnummer=20001272
https://www.fedlex.admin.ch/eli/cc/1959/679_705_685/de
https://www.fedlex.admin.ch/eli/cc/1962/1364_1409_1420/de
https://www.fedlex.admin.ch/eli/cc/1995/4425_4425_4425/en
Cyclists are not allowed to ride next to each other, except in a closed group of more than 10 cyclists, on
cycle paths and signposted cycle paths on secondary roads (VRV Art. 43) and not let themselves be
pulled (SVG Art. 46).
Bicycle trailers must have a triangular reflector on the outside left and right on the front and back.
Blinkers are only allowed if the towing vehicle has them. If the rear light of the towing vehicle is cove-
red, the trailer needs one (VTS Art. 210).
Bicycles and bicycle trailers must not be wider than 1 m; for transporting disabled people up to 1.3 m
(VTS Art. 213, VRV Art. 68). The load of a trailer may not overhang by more than 50 cm, the total
weight of the trailer may not exceed 80 kg (VRV Art. 68).
Bicycles must have two brakes, one each on the front and rear wheel. With Multitrack, the two brakes
may also act on two front/rear wheels if the braking effect is just as good and the vehicle keeps its
course; In addition, a brake must be lockable so that the fully loaded vehicle is prevented from rolling
down a gradient of up to 12% (VTS Art. 214).
Co-drivers are only allowed on seats set up for this purpose (SVG Art. 30) – a maximum of as many
co-drivers as there are corresponding pairs of pedals, or a maximum of two children or one disabled
person (VTS Art. 215, VRV Art. 63).
Lighting must be used between dusk and the next daylight, in poor visibility conditions and in tunnels
(VRV Art. 30). A white headlight must be used at the front and a red taillight at the rear. They must
not dazzle or flash and must be visible at 100 m at night (SVG Art. 216).
Motorized bicycles count as motor vehicles and must therefore also be driven with lights during the
day - with daytime running lights or low beams (VRV Art. 30).
Yellow, non-dazzling, symmetrically arranged indicators are permitted (SVG Art. 216).
Reflectors (front: white; rear: red; SVG Annex 10.1) or other reflective devices with the same effect
with a luminous surface of at least 10 cm2 must be permanently attached at the front and rear, which
are visible at 100 m at night are. Multitrack must have reflectors on both sides (SVG 217).
Os pedais devem sempre ter refletores amarelos (SVG Apêndice 10.1), mas os pedais de corrida e de
segurança são excluídos (SVG Art. 217).
Situação jurídica na Holanda 
Nos Países Baixos, a lei relevante é o Reglement verkeersregels en verkeerstekens 1990 (RVV 1990) :
Há uma obrigação de usar ciclovias marcadas com o sinal G11, G12a ou G13 (RVV Art. 5.1). Há também
ciclovias não obrigatórias.
Veículos de várias faixas e bicicletas com reboques estão isentos da obrigação de usar a ciclovia se fo-
rem mais largos que 0,75 m (RVV Art. 5.4).
Se não houver passagem para pedestres, os pedestres também podem caminhar na ciclovia (RVV Art.
4.2).
Não há limites gerais de velocidade para bicicletas (RVV Art. 5.20, 5.21 e 5.22).
As bicicletas devem andar com as luzes acesas à noite ou em condições de pouca visibilidade; É neces-
sário um farol branco ou amarelo na frente e uma luz traseira vermelha na traseira (RVV Art. 35.1 e
35.2). As luzes não devem piscar. Não há outros requisitos.
Os veículos multipista com duas rodas dianteiras devem ter dois faróis dispostos simetricamente (RVV
Art. 35.3).
Indicadores amarelos são permitidos (RVV Art. 35.4).
Situação jurídica na Bélgica 
Na Bélgica, o trânsito rodoviário é regulado no Wegcode (ou Code de la route ). Para ciclistas:
Bicicletas são veículos com duas ou mais rodas que são movidos exclusivamente por força humana.
Reclináveis e velomobiles são explicitamente incluídos. Multi-pista são consideradas bicicletas até
uma largura máxima de 1 m. (Art. 2.15.1).
Uma bicicleta com um motor auxiliar de até 250 W e até 25 km/h de assistência ao pedalar também é
considerada uma bicicleta. Por outro lado, se a motorização for de até 1 kW, é uma “gemotorised
rijwiel” (= bicicleta motorizada) (Art. 2.15.1 e 2.15.3).
Um velomóvel motorizado mais potente (até 4 kW de potência de tração), por outro lado, conta como
um “bromfiets” (= ciclomotor), dependendo da velocidade máxima relacionada ao design como
“bromfiets classe A” (25 km/h) ou “bromfiets classe B” (45 km/h).No entanto, não é considerado um
“pedelec de velocidade” porque isso inclui apenas veículos de duas rodas. São permitidos até dois as-
sentos (Artigo 2.17).
As ciclovias e as ruas para pedestres/ciclistas/motociclistas/pedelecs de velocidade aplicam-se aos ve-
lomóveis, mas não aos ciclomotores (= velomóveis fortemente motorizados) (Art. 2.34, 2.61).
Bicicletas, ciclomotores classe A e pedelecs de velocidade devem ser usados em ciclovias ou caminhos
compartilhados e ciclovias. No entanto, bicicletas reclinadas e velomobiles com largura máxima de 1 m
e pedelecs de velocidade com limite de velocidade de 50 km/h ou menos são livres para escolher se
querem usar a ciclovia ou a estrada (Artigo 9.1.2).
Os ciclomotores da classe B só podem circular nas ciclovias se o limite de velocidade na via for de no
máximo 50 km/h e não colocarem em perigo os outros utilizadores da via (artigo 9.1.2).
Na Valônia, aplica-se um limite de velocidade de 50 km/h em áreas urbanas e 30 km/h em ciclovias
(Artigo 11.1).
Um limite de velocidade de 25 km/h se aplica aos ciclomotores da classe A (Artigo 11.3).
Veículos de três e quatro rodas não motorizados (ou seja, velomobiles) e qualquer tráfego local tam-
bém são permitidos em estradas para tráfego agrícola, bicicletas e cavaleiros. Um limite de velocidade
de 30 km/h se aplica (Art. 22-8).
Nas ciclovias aplica-se um limite de velocidade de 30 km/h; os carros não podem ultrapassar bicicletas
(Art. 22-9).
Somente pedestres, bicicletas e speed pedelecs são permitidos nas ruas escolares (marcadas pela pala-
vra “schoolstraat”), assim como veículos de emergência e carros com licenças especiais. Os carros de-
vem dirigir em velocidade de caminhada e dar passagem a pedestres e ciclistas (Art. 22-11).
No escuro ou quando a visibilidade for inferior a 200 m, as bicicletas devem estar equipadas com luzes
(Artigo 30.3).
Bicicletas e ciclomotores de duas rodas devem ser ultrapassados a uma distância de pelo menos 1 m,
fora das cidades, pelo menos 1,5 m. O tráfego rodoviário só pode cruzar ciclovias em velocidade mode-
rada e sem impedir/colocar em risco o tráfego de bicicletas (Artigo 40-3).
Os ciclistas e condutores de ciclomotores não devem andar com as mãos livres, devem manter sempre
os pés nos pedais e não devem deixar-se puxar (Artigo 43.1).
Ciclistas podem andar lado a lado, desde que possam ser ultrapassados. Com um trailer, em uma faixa
de ônibus ou com uma motoneta, você tem que dirigir em uma fileira (Artigo 43.2).
Grupos de 15 a 50 ciclistas não precisam usar ciclovias e podem pedalar lado a lado. Grupos de até 150
ciclistas precisam de dois veículos de escolta e dois guias (Art. 43-2).
Uma bicicleta sem motor pode ter no máximo 2,50 m de comprimento, incluindo a carga; esta pode
sobressair no máximo 0,50 m para trás (artigo 46.º).
https://wetten.overheid.nl/BWBR0004825/2021-07-01
https://www.wegcode.be/nl/regelgeving/1976101105/fietsers~hra8v386pu
No escuro ou quando a visibilidade for inferior a 200 m, as bicicletas devem estar equipadas com lu-
zes; ou seja, um farol branco ou amarelo na frente e uma luz traseira vermelha na traseira (Art. 30.3),
que seja visível a uma distância de pelo menos 100 m no escuro (Art. 82.1.1).
Deve haver um refletor branco na frente e um vermelho atrás; este último separadamente da luz tra-
seira. Os pedais devem ter refletores de pedal e todas as rodas devem ter pelo menos dois refletores de
raios amarelos ou uma faixa refletiva branca no pneu (art. 82.1.1). Os refletores não devem ser triangu-
lares (art. 82.1.4).
Bicicletas com diâmetro de roda de até 500 mm, bicicletas sem bagageiro, com guidão drop e pneus de
no máximo 25 mm de largura, bem como bicicletas com pneus de pelo menos 38 mm de largura com
diâmetro de roda de 650 mm ou pneus de pelo menos 32 mm de largura com diâmetro de roda de 700
mm e sem para-lamas e sem bagageiro não têm iluminação à luz do dia. Se tiverem para-lamas, tam-
bém devem ter os refletores dianteiros/traseiros brancos/vermelhos (art. 82.1.1).
Os triciclos e quadriciclos devem ter mais refletores: se houver duas rodas dianteiras, dois refletores
brancos na frente; se houver duas rodas traseiras, dois refletores vermelhos atrás, cada um com o
mesmo formato e tamanho (Art. 82.1.4).
As bicicletas podem ser equipadas com indicadores amarelos ou laranja (Art. 82.1.5).
As bicicletas devem estar equipadas com uma campainha ou similar que possa ser ouvida a uma dis-
tância de pelo menos 20 m (Artigo 82.2).
As bicicletas devem ser equipadas com dois freios, um na roda dianteira e um na roda traseira - exceto
se o diâmetro da roda for de 500 mm ou menos, caso em que um freio é suficiente. Para triciclos e qua-
driciclos, o único requisito é que o sistema de frenagem seja suficientemente eficaz (Artigo 82.3).
As bicicletas podem ter até 0,75 m de largura, os triciclos e quadriciclos até 2,50 m de largura e os re-
boques de bicicletas até 1 m de largura (mas não mais largos que o triciclo ou quadriciclo de reboque)
(Artigo 82.4).
Um reboque de bicicleta pode pesar até 80 kg, com um freio de inércia ainda maior (Artigo 82.5).
Situação jurídica na França 
Observação: alguns dos artigos abaixo podem estar desatualizados em relação à versão mais recente do
`Code de la route https://www.legifrance.gouv.fr/codes/texte_lc/LEGITEXT000006074228?
etatTexte=VIGUEUR`__ .
Os regulamentos específicos para ciclistas são:de passageiro (exceto tandems) devem ter cinto de segurança ou alça de apoio e
dois apoios para os pés. Crianças menores de 5 anos devem usar uma cadeira especial para crianças
(Art. R431-11).
Situação jurídica no Reino Unido 
No Reino Unido, as regras de trânsito são resumidas no Código de Estradas . Este não é um corpo de leis,
mas contém tanto conselhos quanto regulamentos (com referência às leis relevantes). Os regulamentos
mais importantes para ciclistas são:
Um farol branco, uma lanterna traseira vermelha, um refletor vermelho e refletores de pedal são obri-
gatórios à noite (Regra 60). Refletores adicionais são recomendados, luzes piscantes são permitidas.
Não há obrigação de usar ciclovias, mas é proibido andar na calçada (Regra 64).
É proibido o uso de celulares ou similares durante a condução (Regra 149).
Ciclistas não estão autorizados a circular em autoestradas (Regra 253).
Situação jurídica na Dinamarca 
Na Dinamarca, o ciclismo é regulamentado em Færdselsloven :
Os pedestres (incluindo, por exemplo, patinadores) podem andar na ciclovia se não houver passagem
para pedestres e eles não atrapalharem os ciclistas (§10).
Os ciclomotores devem usar a ciclovia, a menos que especificado de outra forma por meio de placas
(§14.2).
Os ciclistas também podem ultrapassar pela direita (§21).
https://www.securite-routiere.gouv.fr/reglementation-liee-aux-modes-de-deplacements/velo/regles-de-circulation-pour-les
https://www.securite-routiere.gouv.fr/reglementation-liee-aux-modes-de-deplacements/velo/regles-de-circulation-pour-les
https://www.gov.uk/guidance/the-highway-code
https://www.retsinformation.dk/eli/lta/2021/1710
Nas paradas, os pedestres têm prioridade ao atravessar a ciclovia (§27.4).
Embora bicicletas de duas rodas possam circular lado a lado se houver espaço suficiente, isso nunca é
permitido para Multitrack (§49.1).
Há também o Bekendtgørelse om cyklers indretning og udstyr com os seguintes regulamentos:
Bicicletas que são legais na UE, Turquia ou um estado do EEE também podem ser usadas na Dina-
marca (§2.3).
As bicicletas podem ter no máximo quatro rodas e os reboques para bicicletas podem ter no máximo
duas rodas (§3).
Um veículo com várias faixas pode ter até 1,25 m de largura (com carga; sem espelhos etc.) (§5.1).
Uma bicicleta não deve ter mais de 3,5 m de comprimento (incluindo carga, incluindo reboque) (§5.3,
§6.1).
Uma bicicleta deve ter pelo menos dois sistemas de travagem independentes que atuem nas rodas di-
anteiras e traseiras (§7).
Uma bicicleta deve ter um farol branco ou amarelo (visível a 300m) e uma lanterna traseira vermelha.
O brilho deve ser de pelo menos 4 cd na linha de visão e 0,4/0,05 cd em 20°/80° da lateral (§8.1, §9).
No caso de um carro com várias faixas, o farol pode estar a no máximo 0,5 m da borda esquerda; a
partir de uma largura de 1 m, duas luzes traseiras devem ser montadas a uma distância de pelo menos
0,6 m (§8.2).
Refletores de pedal amarelos e refletores de raios amarelos ou refletores de pneus brancos são obriga-
tórios (§18, §19).
Frente e traseira devem ter refletores branco/vermelho. Todos os refletores devem estar em conformi-
dade com o Regulamento UN/ECE 88 (§33).
Um veículo com várias faixas deve ter indicadores de direção e luzes de freio âmbar se a
conversão/frenagem não puder ser indicada com o braço (§13).
Uma bicicleta deve ter uma campainha; a buzina é proibida (§23).
Um motor auxiliar pode ter uma potência máxima de 250 W e suportar até uma velocidade máxima de
25 km/h, até 6 km/h sem pedalar (§27).
https://www.retsinformation.dk/eli/lta/2016/976
Contribuidores e Fontes 
Versão 3.0 (commit Git: 7ca4fd1 , data: 2022-12-20)
Colaboradores:
Texto e diagramas: Christoph Moder (1978-2022)
Edição de tradução em inglês: Tony Grant
Controle deslizante VM: Jockel Hofmann
Fontes:
Fig. 1 : LazyBiker
Fig. 3 , 6 ,%s: dados Intercitybike , Velomobiel (em: 2020-02-29)
Fig. 4 : dados (em: 2020-03-04)
Fig. 5 : dados de Christian Schulz , online no Google Maps .
Fig. 7 : dados do site Velomobile World (em 11/11/2021) e números de produção anteriores da Velo-
mobiel e da InterCityBike .
Fig. 9 : É uma adaptação de um gráfico da Wikipedia originalmente criado pelo usuário Bromskloss e
licenciado sob a GNU Free Documentation License 1.2 e a Creative Commons CC-BY-SA .
Fig. 11 : WeLi-Arno
Fig. 12 , Fig. 22 : dados do BicycleRollingResistance.com (autor: Jarno Bierman, em 04/07/2020).
Fig. 30 : dados do VM-Slider , veja as fontes lá.
Fig. 16 , Fig. 24 , Fig. 18 : Dados de GPS de Christoph Moder, dados de elevação do Surveying Office.
fig_pants_alpha7_df, :numref:`21 : Fotos Christoph Moder
Fig. 33 : topografia dos dados do SRTM, usuários do velomobile dos dados da Fig. 3 e da lista de mem-
bros do fórum do velomobile, geocodificados via Nominatim .
Fig. 35 : densidade populacional por regiões NUTS-3 a partir de dados do Eurostat (a partir de 2019),
utilizadores de velomobile a partir de dados da Fig. 3 e da lista de membros do Velomobile Forum, ge-
ocodificados via Nominatim .
Outros diagramas: calculados com NumPy e desenhados com Matplotlib .
Foto da capa: Velomobile DF em Walchensee, vista do leste em direção a Sachenbach, foto de Chris-
toph Moder.
Contracapa: Dias de caminhada reclinada da Baviera em Ornbau 2021, no acampamento, foto de Ch-
ristoph Moder.
Modelo 3D : Aus Thingiverse do usuário hausmilbe ; Licença: GNU LGPL . Com visualização e filtro
suaves , dizimados e limpos .
https://gitlab.com/cmoder/velomobil-grundwissen/
https://christoph-moder.de/
https://www.velomobilforum.de/forum/index.php?members/anotherkiwi.21983/
https://www.velomobilforum.de/forum/index.php?members/24kmh_sammler.17233/
https://www.velomobilforum.de/forum/index.php?members/lazybiker.21824/
https://www.intercitybike.nl/rijderslijst/index.php?amount=0
http://www.velomobiel.nl/rijderslijst/index.php?amount=0
https://www.velomobilforum.de/forum/index.php?threads/velomobil-alter-hase-oder-junger-spund.47682/
https://www.velomobilforum.de/forum/index.php?members/hellrich.18913/
https://www.google.com/maps/d/viewer?hl=de&mid=1Mr5RVj9MMaFSy7xnXUbZmODqEAZDI4n1
https://www.velomobileworld.com/de/auftraege/
https://www.velomobiel.nl/orderboek/
https://www.velomobiel.nl/orderboek/
https://www.intercitybike.nl/en/orderboek/
https://commons.wikimedia.org/wiki/File:Ackermann_radius_M.svg
https://commons.wikimedia.org/wiki/Commons:GNU_Free_Documentation_License,_version_1.2
https://creativecommons.org/licenses/by-sa/3.0/deed.de
https://www.velomobilforum.de/forum/index.php?members/weli-arno.8903/
https://www.bicyclerollingresistance.com/road-bike-reviews
https://cmoder.gitlab.io/velomobil-grundwissen/vm-slider/vm-slider.html
http://nominatim.org/
https://ec.europa.eu/eurostat/estat-navtree-portlet-prod/BulkDownloadListing?dir=data&sort=1&sort=2&start=d
http://nominatim.org/
https://numpy.org/
https://matplotlib.org/
https://www.thingiverse.com/thing:1542704
https://www.gnu.org/licenses/old-licenses/lgpl-2.1.html
http://paraview.org/
Cálculos e parâmetros 
Todos os diagramas neste livro são calculados com os seguintes parâmetros e fórmulas:
Massa do condutor: 75 kg
Massa do velomóvel: 25 kg
Área da seção transversal efetiva: 0,05 m 
2
Coeficiente de resistência ao rolamento: 0,005 (e = 0,1)
Perdas de condução: 8%
Os cálculos exatos podem ser encontrados no código-fonte dos scripts no repositório Git do livro .
..index:: ! resistência ao rolamento, resistência dinâmica ao rolamento, somador
Resistência ao rolamento 
Resistência ao rolamento é a força necessária para rolar uma roda sobre uma superfície áspera. Depende
principalmente da carga; todas as outras influências são resumidas em uma constante, o coeficiente de re-
sistência ao rolamento (veja também: `O que é resistência ao rolamento?`_ ). Então a fórmula é:
A força normal é , ou seja, a proporção do peso (= massa vezes aceleração gravitacional) que
pressiona verticalmente a superfície. Então a massa entra linearmente, a velocidade não importa.
Potência é trabalhopor tempo, ou seja, força vezes distância dividida pelo tempo, ou força vezes veloci-
dade somada:
Portanto, a potência de resistência ao rolamento aumenta linearmente com a velocidade .
No entanto, as medições mostram que a força de resistência ao rolamento não é constante, mas depende
da velocidade (veja: `O que é resistência ao rolamento?`_ ). De acordo com a convenção de cálculo de
Kreuzotter, as seguintes fórmulas resultam:
coeficiente de resistência ao rolamento 
O site Bicycle Rolling Resistance oferece o que provavelmente é o teste mais abrangente e consistente de
pneus de bicicleta. Lá, os pneus são testados em um tambor de 77 cm, com uma carga de 42,5 kg, veloci-
dade e temperatura do ar constantes e após uma fase de aquecimento de 30 minutos.
Como você pode ver na Fig. 12 , o coeficiente de resistência ao rolamento dos pneus de bicicletas de es-
trada está principalmente na faixa entre 0,003 e 0,006.
No entanto, pneus rápidos são testados lá apenas em tamanhos de bicicletas de corrida, enquanto as rodas
dianteiras do velomóvel são significativamente menores. Portanto, pode-se presumir que a resistência ao
rolamento de pneus pequenos é ligeiramente maior - se o material e a produção forem idênticos aos dos
pneus grandes. Além disso, as rodas dianteiras da maioria dos velomóveis têm uma cambagem negativa;
isso também deve aumentar um pouco a resistência ao rolamento (veja: `Por que as rodas dianteiras estão
inclinadas? Isso não freia?`_ ).
Outra fonte para medições de resistência ao rolamento é o blog de Wim Schermer ; em seus testes, ele se
concentra em tamanhos de pneus para velomobiles e reclinados. No entanto, ele não usa um dinamômetro
de rolo, mas seu método de pêndulo - duas rodas conectadas a um eixo carregam um peso excentricamente
preso, de modo que a construção rola para frente e para trás. No entanto, alguns de seus resultados de me-
dição não são consistentes com os resultados de medição do suporte de teste de rolo e também com as ex-
periências subjetivas de muitos motoristas. Provavelmente é devido à baixa velocidade de rolamento do
método do pêndulo e, portanto, à resistência dinâmica ao rolamento , que faz com que a resistência total
ao rolamento aumente acentuadamente em altas velocidades.
Resistência dinâmica ao rolamento 
É amplamente aceito que métricas de potência são melhor explicadas em termos de uma força de resistên-
cia ao rolamento, que não é constante, mas aumenta com a velocidade. No entanto, quase não há medições
do coeficiente de resistência ao rolamento dinâmico, e nenhuma explicação conclusiva da causa.
Na calculadora Kreuzotter é assumido, assim como nos diagramas aqui. Isso significa, por exem-
plo, que um coeficiente de resistência ao rolamento de 0,005 medido pela Bicycle Rolling Resistance a
28,8 km/h corresponde a um coeficiente de resistência ao rolamento base de 0,0042.
Outra medição vem de Charles Henry , determinada em um suporte de teste de rolo; ele chega a um au-
mento médio diário no coeficiente de resistência ao rolamento em 0,0001 por m/s de aumento na veloci-
dade. No exemplo anterior, o coeficiente de resistência ao rolamento base também seria 0,0042.
No entanto, seu gráfico também mostra que o aumento no coeficiente de resistência ao rolamento não é li-
near – é mais pronunciado em baixas velocidades e que o aumento é diferente para pneus diferentes.
A resistência ao rolamento da bicicleta também tem uma pequena medição , mas com pressão de pneu
relativamente baixa; aqui o resultado é significativamente menor, ou seja, 0,000067 por m/s.
temperatura e humidade 
Quando se trata de arrasto, os efeitos das mudanças de temperatura são bastante claros; a temperatura
influencia a densidade do ar , que diminui com o aumento da temperatura:
A humidade também influencia a densidade do ar (através da constante dos gases ); diminui com o au-
mento da umidade. No entanto, a influência da temperatura e da umidade na resistência do ar é bem pe-
quena em temperaturas externas normais.
A resistência ao rolamento é completamente diferente. Isso também aumenta com a diminuição da tempe-
ratura, mas de forma não linear - em alguns casos, aumenta drasticamente perto do ponto de congela-
mento, de modo que um bom pneu de verão se torna uma âncora de freio no inverno. Dependendo do
pneu, no entanto, a dependência da temperatura difere muito; pneus de parede grossa tendem a ser mais
dependentes da temperatura. O material da câmara de ar da bicicleta também desempenha um papel; Em
baixas temperaturas, as mangueiras de butil se tornam mais lentas do que as mangueiras de látex. A razão
para essas dependências de temperatura não é clara, então elas não podem ser calculadas, e as medições
são complexas e, portanto, dificilmente disponíveis.
cdyn
cR
Froll = cR ⋅ FN
FN = m ⋅ g
Proll = Froll ⋅ v = cR ⋅ m ⋅ g ⋅ v
v
Froll = cR ⋅ FN + cdyn ⋅ v
Proll = Froll ⋅ v = cR ⋅ m ⋅ g ⋅ v + cdyn ⋅ v2
cdyn = 0.1
T
ρ
ρ =
p ⋅ M
R ⋅ T
R
https://gitlab.com/cmoder/velomobil-grundwissen/-/blob/master/data/
https://www.bicyclerollingresistance.com/
http://wimschermer.blogspot.com/search/label/bandentest
http://wimschermer.blogspot.com/2011/07/oscillerend-banden-test-apparaat.html
https://www.velomobil.ch/ch/de/rollenpruefstand
https://www.bicyclerollingresistance.com/specials/crr-speed-test
A umidade também afeta a resistência ao rolamento; a resistência ao rolamento é maior em estradas mo-
lhadas. Forças adesivas provavelmente são a causa; elas provavelmente não são facilmente calculáveis.
resistência do ar 
O arrasto é fundamentalmente complicado (veja: O que é arrasto? ); mas para cálculo ele é geralmente re-
duzido à resistência à pressão e empacota todos os outros efeitos no valor c 
W
 (veja: O que é o valor cW? ).
Portanto, a força de arrasto é simplificada pela pressão dinâmica ( ), que atua na área da
seção transversal efetiva :
Assim, a área da secção transversal e a densidade do ar tem um efeito linear na resistência do ar, mas a
velocidade tem um efeito quadrado na força de arrasto e até mesmo na terceira potência na potência.
No entanto, como os velomóveis têm um formato bastante aerodinâmico, não apenas a resistência à pres-
são desempenha um papel, mas também a resistência ao atrito. Isso significa que não é apenas o formato e
a área da seção transversal que importam, mas também a área total da superfície no fluxo - uma grande
área de superfície fornece muito atrito de superfície e é refletida em um valor c 
W
 aumentado .
coeficiente de arrasto 
As medições de resistência do ar são caras; para medi-las independentemente da resistência ao rolamento,
você precisa de um túnel de vento, e há correspondentemente poucas medições. Provavelmente a única
medição de vários tipos diferentes de velomóveis foi realizada na Universidade Ostfalia em Wolfenbüttel;
os resultados foram publicados em 2022 na publicação “ ` Medição da resistência do ar de vários velomó-
veis no túnel de vento HU Meier ”. __” publicado por Velten et al. .
As áreas da seção transversal dos velomóveis medidos estão entre 0,393 m 
2
 e 0,472 m 
2
 , com os velomó-
veis conhecidos por serem rápidos todos estando em torno ou abaixo de 0,41 m 
2
 .
O valor c 
W
 para o velomóvel com capuz a 53 km/h estava na faixa entre 0,11 e 0,17; a área transversal efe-
tiva (mais relevante) para esses veículos estava entre 0,044 m 
2
 e 0,071 m 
2
 . Houve apenas uma pequena
diferença entre velomóveis com casas do leme abertas e fechadas en (ou calças ). No entanto, a medição
não foi realizada com as rodas girando, então, na realidade, velomóveis com arcos de roda fechados devem
ter uma vantagem maior.
Além disso, o solo estava parado, então ele não se movia em relação ao velomóvel como uma estrada. Isso
significa que o fluxo na parte inferior da carroceria é ligeiramente diferente na realidade do que no túnel
de vento. (No entanto, pelo menos a distância até o solo foi aumentada parareduzir a influência de sua ca-
mada limite.) E como os velomóveis estavam parados, não havia vibrações na carroceria, como seria o caso
na estrada. Os resultados da medição, portanto, não são diretamente transferíveis para a realidade.
Um resultado interessante, no entanto, é que para os velomóveis rápidos o valor c 
W
 diminuiu com a velo-
cidade em todas as medições. Isso não é totalmente surpreendente; esse valor é apenas uma constante
aproximada para um fluxo turbulento (veja: O que é o valor cW? ) - para esses velomóveis o número de
Reynolds deve, portanto, ainda estar próximo da faixa laminar.
perdas de condução 
Em uma bicicleta, há perdas dependentes de carga e independentes de carga. Consequentemente, a efici-
ência depende da potência de pedalada - quanto maior, melhor a eficiência, porque as perdas independen-
tes de carga são menos importantes.
Com uma transmissão por corrente limpa e bem lubrificada, as perdas de transmissão podem ser de 2% ou
menos. Com engrenagens desviadoras, as rodas jockey são adicionadas; se estas estiverem funcionando
suavemente, as perdas de transmissão podem ser igualmente baixas - no entanto, podem ser de 5% ou
mais se a corrente estiver torta e suja (cada uma com base em uma alta potência de pedalada). O mesmo se
aplica às engrenagens do cubo: embora as perdas na engrenagem direta também possam ser de 2% ou me-
nos, elas aumentam para 5% ou mais em outras engrenagens ( Speedhub, medido por Rohloff ). Uma me-
dição de Andreas Oehler apresenta perdas consistentemente maiores: engrenagens desviadoras e engre-
nagens de cubo boas têm cerca de 5% de perda, engrenagens de cubo ruins chegam a 10% de perda ou
mais.
Não há estudo sistemático para velomóveis, então as perdas só podem ser estimadas. Velomóveis geral-
mente têm engrenagens desviadoras (com quase nenhuma inclinação), mas também há duas polias de de-
flexão no trem de força (= perdas dependentes da carga) e no lado frouxo uma corrente esfregando no tubo
da corrente (= perdas independentes da carga). Então você tem que assumir perdas de 5%-10%. Kreuzot-
ter assume uma perda de potência de 8,3% em sua calculadora de desempenho.
pdyn = 1/2 ⋅ ρ ⋅ v2
Fair = pdyn ⋅ Aeff =
1
2
⋅ cW ⋅ A ⋅ ρ ⋅ v2
Pair = Fair ⋅ v =
1
2
⋅ cW ⋅ A ⋅ ρ ⋅ v3
A ρ
v
https://www.ostfalia.de/cms/de/m/fakultaet-maschinenbau/News/Velomobil_Vergleichsmessung_HUM.pdf
https://www.ostfalia.de/cms/de/m/fakultaet-maschinenbau/News/Velomobil_Vergleichsmessung_HUM.pdf
https://www.rohloff.de/de/erleben/technik-in-detail/efficiency/efficiencymeasurement
https://fahrradzukunft.de/17/efficacy-measurements-an-nabenschalten-2#results
https://fahrradzukunft.de/17/efficacy-measurements-an-nabenschalten-2#results
Glossário 
aerobelly 
Uma quantidade maior de tecido adiposo visceral ( bioprene ), jocosamente dito para melhorar a aero-
dinâmica – mas irrelevante em velomobile. Também chamado de cofre de alimentos finos , grande
músculo ou cemitério de bolinhos .
resistência do ar 
Força que tem que ser usada para deslocar o ar. A fórmula é isto é, a
área da seção transversal A é linear e a velocidade v é ao quadrado. O fator corresponde à
pressão dinâmica, que depende da velocidade (quadrado) e densidade do ar (linear).
vento aparente 
Soma vetorial do vento (“vento verdadeiro”) e do vento contrário – se, por exemplo, o vento verda-
deiro e o vento contrário forem do mesmo tamanho e o vento verdadeiro vier da lateral em ângulos re-
tos, então o vento aparente vem em um ângulo de 45° da frente e é, de acordo com o teorema de Pitá-
goras, 41% mais forte que o vento verdadeiro e o vento contrário.
pé grande 
componente do velomóvel DF, onde o mastro do movimento central suporta a extremidade traseira.
biopreno 
Nome brincalhão para gordura corporal que, como o neoprene por exemplo, fornece isolamento tér-
mico e acolchoamento, mas também serve como um armazenador de energia e não adiciona peso à
bicicleta.
abertura do corpo 
O ângulo entre o tronco e as pernas. Muitas pessoas conseguem escalar melhor quando esse ângulo é
menor, ou seja, elas sentam mais eretas ou a inclinação do suporte inferior é maior.
círculo de parafusos 
Diâmetro onde os parafusos de fixação da coroa estão localizados. Os padrões comuns são 130 mm e
110 mm (pedaleira compacta) e 104 mm (mountain bike).
Boruttisieren (precisa de equivalente em inglês) 
proteção contra roubo, ao fazer a bicicleta parecer feia e negligenciada, faz com que pareça pouco atra-
ente para os ladrões.
mastro do movimento central 
Mastro que vai da ponte de direção até a frente e geralmente é preso à frente do velomóvel no funil, e
carrega o suporte inferior com as manivelas e pedais. Para que isso possa ser ajustado, o próprio mas-
tro é ajustável (por exemplo, extensível e giratório), ou o suporte inferior é preso de forma deslizante
no mastro. Quando o mastro é preso na frente, o ar fresco geralmente também é direcionado através
do mastro para a traseira.
elevação do suporte inferior 
A diferença de altura entre o suporte inferior e o ponto mais baixo da estrutura do assento. Para um
ângulo de abertura ideal do corpo e a menor área transversal possível, a elevação deve ser relativa-
mente grande, por outro lado, as pernas ficam então no campo de visão – especialmente quando tam-
bém estão cercadas por um corpo.
camada limite 
área de um fluido fluindo perto de uma superfície na qual sua velocidade é relativa à superfície cres-
cendo de zero até a taxa de fluxo do fluido restante. Isso pode ser laminar (ou seja, há uma velocidade
dentro do gradiente de corrente) ou turbulento (ou seja, há pequenos vórtices ao longo da superfície
que são separados do fluxo laminar).
tapete bovino 
Nome brincalhão para uma almofada de assento feita de pele de cordeiro
âncora de freio 
Um pneu com resistência ao rolamento muito alta . Pneus de paredes particularmente grossas com in-
serções de proteção contra furos parecem predestinados para esse nome.
Bump Steer 
Influência da direção induzida pela suspensão, veja O que é “Bump Steer”? ,
curvatura 
Inclinação da roda de modo que ela não fique perpendicular à estrada, mas inclinada para fora (“cam-
ber positivo”) ou para dentro (“camber negativo”). Veja: Por que as rodas dianteiras estão em um ân-
gulo? Isso não te deixa mais lento?
rodízio 
A distância entre o ponto de rastreamento e o ponto de contato de uma roda esterçada. Se for positivo,
ou seja, o ponto de contato da roda estiver atrás do ponto de rastreamento, a roda segue a direção do
quadro – ou do ponto de vista do quadro, a roda esterçada retorna automaticamente para a posição
reta. Você pode obter um caster positivo colocando o mancal de direção na frente da roda ou, se não
for o caso, incline o eixo de direção de modo que sua extensão aponte para a frente da roda. Veja: O
que é caster e qual é sua função?
catenária 
Uma corrente de bicicleta tem um certo grau de mobilidade lateral, mas não deve correr em um ângulo
permanentemente, pois isso aumenta a resistência da pedalada e o desgaste. No entanto, em velomo-
biles, os rolos de deflexão estão longe o suficiente da coroa ou pinhão para que a inclinação seja limi-
tada em todas as marchas. Além disso, os rolos de deflexão em alguns velomobiles podem ser movidos
lateralmente.
capacidade 
Comprimento que um tensor de corrente pode encurtar a corrente. Tensores de corrente com gaiolas
longas, como são comuns no setor de mountain bike, têm capacidade para cerca de 40 elos de cor-
rente. Para poder trocar todas as marchas, a capacidade deve ser igual à diferença entre a soma do nú-
mero de dentes da maior coroa e da maior roda dentada e a soma do número de dentes da menor co-
roa e da menor roda dentada. Se a capacidade não for suficiente, você ainda deve conseguir trocar de
grande para grande, pois, do contrário, uma corrente muito apertada pode causar danos. Com pe-
queno - pequeno, a corrente então cede, mas isso é menos problemático.
carcaça 
A fabric that is embedded in the tyre and absorbs the tensile forces due to the tyre pressure anddefor-
mation. The rubber only ensures the airtightness and grip of the tyre on the road, therefore, damage to
the carcass (e.g. due to a deep cut) often leads to a dent in the tyre or causes the tyre to burst
immediately. To temporarily repair such a flat, patching only is not enough, but you need a piece of so-
lid material that distributes the pressure of the tube to the surrounding enveloppe for example tape.
cente of gravity
Average location of the mass of a body. For many calculations, it can be assumed that the entire mass
of a body is gathered in the cente of gravity and all forces attack there.
chainring
Fair = 1/2 × cW × A × ρ × v2
1/2 × ρ × v2
v ρ
Chainrings are the gears driven by the crank. In order for them to fit a certain crankset, the bolt circle
must match.
chain line
A bicycle chain has a certain amount of lateral mobility, but should preferably not run permanently at
an angle, as this increases the pedal resistance and wear. However, the deflection rollers on velomobi-
les are far enough away from the chainring or sprocket that the skew is limited in all gears. In addition,
the deflection rollers on some velomobiles can be moved laterally.
cleat
Metal plate on the sole of click shoes that locks them into clipless pedals.
clothes hanger
A component in Velomobiel.nl velomobiles, eg the Quest or Strada.
clipless pedal
A pedal on which special shoes (click shoes) snap into place with a metal plate (cleat) and thus atta-
ches the foot solidly. This allows more efficient power transmission because you cannot slide off the
pedal. There are several different systems, those in the racing bike area usually have large triangular
cleats that are attached with three screws. In the mountain bike area, on the other hand, the SPD
system dominates, the smaller cleats of which are fastened with two screws and sunk into the profile of
the sole, so that you can walk quite well with them. In addition, Speedplay is also worth mentioning,
for example, which offers a particularly large turning range.
click shoes
Shoes for click pedals, See also: Do you need click shoes?
compact crankset
A crankset with two chainrings. Since the bolt circle is only 110 mm, a fairly small chainring can be ins-
talled – you can achieve a similarly large transmission range with just two chainrings as with three
chainrings.
CFD
Computational Fluid Dynamics i.e. simulation of the flow of fluids (liquids, but also gases such as air)
by computer.
conch
Hang upside down in the velomobile (so that only the legs are sticking out) to adjust something at the
front, for example on the gear shift. However, many velomobiles now have a maintenance hatch or a
removable front, so that should be largely unnecessary.
control arm
A rod holding the lower end of the strut , typically fixed in the middle of the velomobile, below the ste-
ering bridge. The longer the wishbone, the less its angle changes when the shock absorber deflects, and
the bump steer effect is correspondingly smaller. See: What are all the parts on the chassis called?
crack damper
A rear wheel damper for certain velomobiles. Offers better damping behavior, but has a reputation for
being more sensitive.
delta
tricycle with one wheel in front and two in the back. Named after the Greek letter Delta, which like lo-
oks like a triangle.
development
Distance traveled with one crank revolution, and thus a measurement of the of the drivetrain. The de-
velopment depends on the chainwheel, the selected pinion and the size of the drive wheel and tyre, in
the lowest gear, velomobiles have a development of about 2 m, in the highest gear about 11 m.
dolphining
in hilly terrain you can go quickly and be energy efficient when the hills are not very steep or high –
then you can rest on the flats between. Take up momentum to overcome the slope, and downhill gain
speed for the next hill. Like dolphins swimming, jumping out of the water and not slowing down when
they dive back in.
double manta
Driving style, in which both arms are hanging out of the cockpit. This only works well with tiller han-
dlebars, because tank steering levers are too low to to operate them with arms hanging out. The name
comes from the Opel Manta, whose drivers were known for liking to keep the left elbow out of the win-
dow. Since the velomobile is narrower, it can be used as the poor mans air conditioning – especially in
summer.
effective cross-sectional area
The product of cross-sectional area and drag coefficient ( ). It is a reference value that can be
used to compare the air resistance of bodies of different sizes and shapes - the air resistance corres-
ponds to the dynamic pressure on the effective cross-sectional area.
empty strand
The part of the chain that runs from the sprocket back to the chainring and does not transmit any trac-
tive force ( i.e. is not tensioned) – in contrast to the traction strand.
ETRTO
(European Tyre and Rim Technical Organisation), standard for designating wheel sizes. The diame-
ter is measured up to the height of the rim flange, i.e. that is neither the inner diameter of the rim, nor
the outside diameter of the rim. The specification indicates not the size of the rim, but the total size
with tyre – therefore a mountain bike bike wheel with large tyres can actually be larger than a
theoretically larger road bike wheel.
foam lid
With some velomobiles (especially from the Dutch manufacturers ), the entry opening can not only be
closed with a hood, but alternatively with a flexible lid made of a foam. This is attached from the inside
and offers an opening so that the head can protrude outside, but the rest of the body is largely protec-
ted from the wind and rain. The remaining opening can also be closed for parking.
nel Component at the front at the top into which the bottom bracket mast is glued. Since the funnel is
also at the stagnation point , it directs the fresh air inside through the mast.
gelcoat
Colored synthetic resin, which, as an outer layer, contains fiber composite material, and among other
things protects from UV radiation. Is mainly used in boat building, but also in some velomobiles.
When laminating, the gel coat is first painted into the negative form, then the fiber fabric and epoxy
resin is laid up over it. If no gel coat is used, the finished velomobile must be painted or filmed.
hood
The cover of the entrance hatch, usually with side windows and at the front a hinged motorcycle visor,
is called hood.
HPV
Human Powered Vehicle, so accordingly muscle powered vehicle. Also the name of the German associ-
ation, HPV Germany eV, the international umbrella organization is called IHPV.
cW ⋅ A
hump
Rise in the rim bed of some tubeless rims, which ensures that the tyre remains close to the outside rim
flange and does not slip inside. To do this, you usually have to over-inflate the tyre a bit until the tyre
slides over the hump. You can retrofit a hump yourself by putting a cord on the rim bed parallel to the
rim flange and covering it with tubeless rim tape.
IGUS
A company that produces plastic plain bearings. Since several ball heads are installed in the steering
linkage of a velomobile, you can save a lot of weight with plastic versions.
ingmarize chain
Chain care by not caring for the chain. Since wear is mainly caused by dirt and this adheres
particularly well to oil, an oil-free chain has a certain justification if the chain is permanently exposed
to water and dirt, i.e. you would have to re-oil and the chain is effectively water-lubricated – and the
bike too is used frequently so that the chain does not rust. This is not a good idea in a velomobile be-
cause the chain is exposed to almost no dirt and water, and a clean chain has the least friction if it is
sufficiently oiled.
Kamm tail
A vehicle rear that is not completely tapered, but is cut off sharply. The sharp edge ensures that the
flow is not diverted inwards at the back and swirled there, but abruptly breaks off. Although it is
slightly more inefficient than a long tail,the losses due to the greater turbulence are partially compen-
sated for by the smaller surface area and the lower weight. Named after Wunibald Kamm, hence the
Kamm-tail.
kinetic energy
must be be used to set a mass in motion. The formula is , i.e. the mass m is linear
and the speed v is squared.
multi-track
A vehicle with multiple wheels that do not run in a row. Such a vehicle cannot lean into the curve (ex-
cept for special leaning vehicles), nor does it fall over when it is stationary or a wheel slips.
Meufl
An abbreviation for Mitteleuropäisches Fahrradlabor (Central European Bicycle Laboratory), this is
how Harald Winkler describes his bicycle projects. But he became known in the 1990s for his bicycle
covers made of closed-cell foam, which were aerodynamic and very light. Correspondingly, devilish
mostly means that a component is made of foam.
NACA Duct
See What is a NACA Duct?
Normalized Power
Rides with the same average performance can have very different levels of stress on the body – depen-
ding on how much the performance fluctuates. This is expressed in Normalized Power , an empirical
formula that accounts for power fluctuations against average power. For this purpose, the pedaling
power is calculated as a moving average over 30 seconds, the fourth power is formed, averaged and the
fourth root is taken from it. The result is an average performance that would be just as taxing if the
power output was constant as the fluctuating performance.
out of the saddle
Kicking style in which you stand up from the saddle while rocking your body relative to the bike. Has
the advantage that the pedaling movement is partially decoupled from the crank rotation – you not
only push the pedal down with your legs, but also your body up, and can thus partially compensate for
an unsuitable gear and provide more variety when pedaling. Unfortunately, that’s not possible on re-
cumbents, because you pedal perpendicular to gravity, and therefore you can’t use gravity to
temporarily store pedaling energy.
overrun
The distance between the toe point and the contact point of a steered wheel. If this is positive, ie the
wheel contact point is behind the toe point, then the wheel follows the direction of the frame – or from
the point of view of the frame, the steered wheel returns to the straight-ahead position by itself. A posi-
tive caster can be achieved by arranging the steering bearing in front of the wheel, or if this is not the
case, by tilting the steering axle so that its extension points in front of the wheel. See: What is caster
and what is its function?
pinion
The sprockets are the gears driven by the chain, which sit on the freewheel of the drive wheel. It is
usually a Shimano freewheel body with grooves on which the sprockets sit either individually or rive-
ted together on a common sprocket carrier (“spider”). The entirety of the sprockets is called a cassette.
Pinlock
Pane that is attached to the inside of a motorcycle visor and ensures airtight double glazing. This ser-
ves as thermal insulation and prevents fogging. See: What do you do against fogged windows? and
How does a velomobile drive in winter?
pants
An aerodynamic cover for open wheel wells, See What are pants?,
PCD Bolt circle
Diameter at which the fixing screws of the chainrings are located. Common standards are 130 mm, 110
mm (compact crank) and 104 mm (Mountain bike).
rear derailleur
The rear derailleur is the derailleur system for the pinions, typically on the rear wheel. It is usually
shifted by moving the derailleur cage with the pulley wheels, this also serves as a chain tensioner – the
longer the cage, the greater the capacity of the rear derailleur. In some velomobiles, however, these
tasks are separate, there the rear derailleur pushes the chain to the side using two plates, and the chain
tensioner is located separately at another point.
rolling resistance
force that must be applied to a Roll the wheel over a rough surface. (.. math:: F_text{roll} = c_text{R}
cdot F_text{N})
shock absorber
Part of the strut
single-track
A single-tracker is a bike in which the wheels are one behind the other and which can therefore lean
into the curve. This can be a recumbent bike, but also an upright bike. However, velomobiles are
practically always multiple tracks.
sprocket
The sprocket is the chain-driven gears which are on the freewheel of the drive wheel. It is usually a
Shimano freewheel body with grooves, on which the sprockets slide either individually or riveted to-
gether on a common sprocket carrier (“spider”). The group of sprockets is called a cassette.
snakebite
Ekin = 1/2 × m × v2
Loss of air in the tyre through two holes in the tube that looks like a snake’s bite. The cause is a punc-
ture, The tyre is pressed in so much that the tube is crushed between the tyre and the rim flange, which
leads to the two holes. With higher air pressure and / or wider tyres, the susceptibility to snakebites
can be reduced.
stagnation point
The point in the front of a vehicle where the air does not come in at an angle and is deflected sideways,
but hits the surface perpendicularly and builds up. The kinetic energy of the air results in an increase
in pressure. Here, a ventilation opening is a good idea because, due to the increased pressure, a small
opening is sufficient for a large air throughput. In addition, there is no laminar flow here that could be
disturbed by the opening.
stormstrip
A tape in the longitudinal direction of the vehicle which hinders the overflow in the transverse direc-
tion and thus reduces the susceptibility to cross winds. See: How can wind sensitivity be reduced? ,
stall
Air flow is either laminar to a surface and follows its course, or detaches and swirls. The transition is
relatively abrupt, hence the name.
scoop
The rear upper part of a velomobile that starts behind the head and runs in an arc to the tail. It serves
as an aerodynamic continuation of the head and prevents turbulence there, similar to an oversized
aero helmet. At the same time it is the highest point of the velomobile and because of the strong curva-
ture it is very stiff, so it also serves as a roll bar in an accident.
scarfing
Repair of fiber composites by beveling the fractured surface and inserting matching patches of increa-
sing size. Firstly, this means that there is a large adhesive surface, secondly, the weight hardly increa-
ses as a result of the repair, and thirdly, the adhesive area remains thin and elastic, so that there are no
stress peaks.
saddle
Step by step, when you get out of the saddle and move your body back and forth relative to the bike.
Has the advantage that the pedaling movement is partially decoupled from the crank rotation – with
the legs you not only press the pedal down, but also the body upwards, and can thus partially compen-
sate for an inappropriate gear and provide more variety when pedaling. Unfortunately, this is not pos-
sible on recumbent bikes because you step at right angles to gravity and therefore cannot use weight to
temporarily store pedaling energy.
sealing milk
A latex-containing liquid with which a tubeless tyre is sealed. This is put in before assembly of the tyre,
or can, with the MilkIt systems special valves, be put in after with a syringe. Because the sealing milk
dries out, it needs to be refilled every few months.
steering bridge
Cover between the front wheel wells under which the steering linkage is located (i.e. tie rod and wish-
bone). Since the bridge is quite voluminous and therefore stiff, the bottom bracket mast or the front
pulley is often attached there.
steering knuckle
A fastening at the lower end of the shock absorber, to which the trailing arm, wishbone arm, tie rod
and, in the case of tank steering, the steering levers are attached. See: What are the names of all the
parts on the chassis?
scrub radius
The radius by which the wheel turns around the pivot point of the steering when steering. See What’s
the deal with the scrub radius? and where is the steeringaxis on a MacPherson strut?
straight running
Straight running is positively influenced by a large wheelbase, neutral steering, low sensitivity to wind,
and (especially with a Einspurer) from a large wake.
strut
Part of an independent suspension, on which the wheel hub carrier with suspension and damping Is
provided. Also called MacPherson strut.
tadpole
tricycle with one wheel at the back and two at the front. Named after the tadpole, since that Tricycle is
large at the front and thin at the back.
tyre contact patch
The area of the tyre that is flattened by the load on the road. The size of the patch depends on the load
and the air pressure, since pressure times area equals pressure force, the area is so large that the pres-
sure force equals the load – with higher pressure the tyre patch can be reduced accordingly. The shape
depends on the tyre width, with a wide tyre the tyre contact is short and wide, with a narrow tyre nar-
row and long.
The icing on the cake
is what a hood is called for the Quest velomobile.
tracking
The tracking is ideal when both front wheels point straight ahead with neither toe-in or toe-out.
tracking point
Intersection of the steering axis extended to the street
trailing arm
A rod that holds the lower end of the strut and typically extends from the front end of the wheel well to
the steering knuckle. The farther inside the wheel well and the further to the front of the trailing arm is
attached to the steering knuckle, the further out the directions of trailing arms and wishbones inter-
sect, ie the more negative the steering scrub becomes. See: What are the names of all the parts on the
chassis?
tie rod
Crossbar of the vehicle that connects the two front wheels and transmits the steering movements. With
tiller steering, the steering movement is transmitted to the front wheels via the tie rod, while in the
case of tank steering, the steering levers act directly on the steering knuckles and the tie rod merely
couples the steering movements of both wheels. A tie rod can be continuous or split, in the latter case,
it moves similar to the wishbone when deflected, which reduces the bump steer. See: What are the na-
mes of all the parts on the chassis?
tension strand
The part of the chain that runs from the chainring to the sprocket and is tensioned because it transmits
the driving force – in contrast to the empty strand.
tiller steering
Steering on tricycles, in which a central steering rod moves the tie rod via a universal joint. The En-
glish name originally means boat tiller.
tank steering
Steering on tricycles, where two steering levers steer the wheels on the left and right. The steering le-
vers are connected to the steering knuckles, the tie rod only serves to couple the two wheels and thus
the steering levers.
tubeless
Normally, a tyre only ensures grip on the road and absorbs the forces created through its carcass, the
airtightness is guaranteed by a tube inside. In the case of a tubeless wheel, the tube is dispensed with
because the tyre is made airtight and also sits particularly firmly on the rim. This has a flat rim base
and often also humps to fix the tyre better, In addition, a special rim tape seals the rim bed airtight.
The valve is screwed directly into the rim. Usually, there is also a sealing milk placed in the tyre that
seals small leaks. Eliminating the tube reduces rolling resistance and increases driving comfort, also
lower pressures are possible because no Snakebite may occur and small holes are often sealed by the
sealing milk. But repairing large holes is more complex because the tyre sits more firmly on the rim.
versatile roof
An airy roof, not as closed as a hood , but not as aerodynamic either.
water slide
component of the Alpha7 Velomobile that supports the bottom bracket at the rear end.
wheel well
Housing in which the wheels are located. These serve as aerodynamic fairing, but also to protect
against dirt (like fenders), and since the wheel wells are often an integral part of the body, they also
have a supporting function, For example, the struts are screwed to the wheel wells at the top of the
front wheels.
wheel disks
Discs that are attached to spoke wheels to ensure a smooth surface and thus reduced air resistance.
The discs are usually glued to the rims, if they are made of fabric, also clipped onto the spokes.
wishbone
A rod that holds the lower end of the strut and is typically attached in the middle of the velomobile, be-
low the steering bridge. The longer the wishbone is, the less its angle changes when the shock absorber
is deflected, and the effect of bump steer is correspondingly less. See: What are the names of all the
parts on the chassis?
Index
A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W
A
Acceleration, [1], [2]
acceleration
acceleration distance, [1], [2]
acceleration stretch
Accident
Ackermann condition, [1]
aerobelly
After 7, [1]
age distribution
Agilo
air density, [1], [2]
Air inlet
air inlet
air loss
air resistance, [1], [2]
Air resistance (drag), [1], [2], [3], [4], [5], [6],
[7], [8], [9], [10], [11], [12], [13], [14], [15], [16]
air resistance (drag)
airfoil
airstream, [1], [2]
Alleweder, [1], [2]
Alpha 7, [1], [2]
Alpha 9
Altimeter
altimeter
Altitude, [1]
altitude, [1], [2], [3]
aluminium
angular velocity
apparent wind, [1], [2]
Aquila 2
Arm rests
Armoured steering
asphalt
asphalt pedal boat
Austria
Average Speed
average speed, [1]
B
balancing
Ball bearing
ball bearing
Barlow’s formula
battery
battery management system
Battle Mountain, [1]
Belgium
bell, [1], [2], [3]
belt drive
BentRider Online
Bicycle repair shop
Bicycle Rolling Resistance, [1]
Bicycle trailer
bicycle trailer, [1], [2], [3], [4]
bicycle trailers
bigfoot
bioprene
Black ice
blueprint
body, [1], [2], [3], [4], [5], [6]
Body height
body opening
body opening angle
body size
Bodywork
bodywork, [1], [2]
bolt circle, [1]
bonnet
Boruttisieren (need English equivalent)
bottom bracket, [1]
bottom bracket elevation
Bottom Bracket Mast
bottom bracket mast, [1]
bottom bracket motor, [1], [2]
bottom bracket protrusion
boundary layer, [1], [2]
bovid mat
Brake, [1], [2], [3], [4], [5]
brake, [1]
brake anchor
Brake cable
brake cable
brake cooling, [1]
Brake lever
brake parachute
BRouter, [1]
Bump Steer
bump Steer
bump steer
butyl, [1], [2], [3]
Bülk
C
Cadence
cadence, [1], [2]
Camber
camber
capacity, [1]
Car, [1], [2]
car, [1], [2], [3], [4], [5], [6], [7], [8]
Carbon, [1], [2], [3], [4], [5], [6]
carbon
carcass, [1]
cardan shaft
cassette, [1]
Caster
caster, [1]
catenary
cente of gravity
centre of gravity, [1], [2], [3], [4], [5]
centrifugal force, [1]
CFD, [1]
Chain
chain, [1], [2]
City traffic, [1]
cleat
Click shoes
click shoes
Climbing Work
clipless pedal
clothes hanger
Clothing, [1], [2]
Code de la Route
code de la route
Commute, [1]
compact crank
compact crankset
compulsory use of cycle paths, [1]
compulsory use of the cycle path
conch
constant current source, [1]
control arm
cooling fins
corrosion, [1]
corrugated sheet metal
chain channel
chain hoist
chain line, [1]
chain pull, [1]
chain ring
chain tensioner
chain tube, [1], [2]
chain tunnel
chainring, [1], [2], [3], [4], [5]
Charles Henry
Chassis, [1]
child seat
crack damper
crank, [1]
crank length, [1], [2], [3]
cross-sectional area, [1], [2], [3]
crosswind, [1], [2], [3]
crumple zone
current
cW value, [1], [2]
Cycle Lane
cycle lane
Cycle Lane Obligation
Cycle path
cycle path, [1], [2], [3], [4], [5], [6]
D
damping, [1], [2], [3]
daytime running light
Dealer
delta, [1]
Denmark
Derailleur
derailleur gears
development, [1]
DF, [1], [2]
differential gear, [1]
Dimensions
disc brake, [1]
Distance
dolphining, [1], [2]
Double manta
double manta
drag
drive losses
Drive stiffness, [1]
drive stiffness
Drivers
Dronten, [1]
Drop shape
drum brake, [1], [2], [3], [4], [5], [6]DuoQuest
Durability
duty to use cycle paths
dynamic pressure
dynamic rolling resistance, [1]
dynamic wheel load distribution, [1], [2]
Dynamo
E
effective cross-sectional area, [1], [2]
electrochemical stress series
Electronics
empty strand
Energy saving
engine, [1], [2], [3]
epoxy resin, [1]
ETRTO, [1]
everyday life
F
fading
Flow
flow, [1], [2], [3], [4], [5], [6], [7], [8], [9]
foam cover
foam lid
Fogged up windows
fogged windows, [1]
Foiling
foiling
Foot bumps
Foot holes
foot holes
Four-wheel, [1]
four-wheel
four-wheeler
France
freewheel body
friction, [1], [2]
front derailleur, [1], [2]
front wheel steering
front-wheel steering
FVO
Færdselsloven
G
Garmin
gear gradation
gear graduation, [1], [2]
gear range, [1], [2]
gear ratio
Gear shifter, [1], [2], [3]
Gears, [1], [2]
Gelcoat
gelcoat, [1]
generator
Germany, [1]
Ginkgo bike parts
glare
glass dome
glass fibre
Go-One, [1], [2]
GoldenCheetah
GPS, [1], [2], [3], [4]
Great Britain
ground clearance
H
halfstep
hand crank drive
Headlight
headlight, [1], [2], [3], [4], [5]
Headlights
headlights, [1], [2]
Headwind
heat capacity
homemade
Hood, [1], [2]
hood, [1], [2], [3], [4]
horn, [1], [2], [3]
Höhe
HPV, [1]
hub dynamo
hub gears, [1]
helmet
Highway Code
Hilgo
hub motor
humidity, [1]
hump
hysteresis, [1]
I
Idler pulley, [1]
idler pulley, [1], [2]
IGUS
independent suspension
Indicator
indicator, [1]
indicators, [1], [2], [3]
ingmarize chain
inner tube
Insurance
insurance number plate
insurance plate
intermediate gear
intermediate gears
interval braking
J
jockey wheels joint cartilage
K
K-tail
Kamm tail
Kestrel
kinetic energy, [1], [2], [3], [4], [5], [6], [7],
[8]
kit
knee problems
Kreuzotter
L
lacquering
laminar flow, [1]
lateral control, [1]
lateral force
lateral guidance, [1]
latex, [1], [2], [3], [4], [5]
Law, [1], [2], [3], [4], [5], [6]
law, [1]
Le Mans, [1]
LED, [1], [2]
leg length
Leiba
Leiba Cargo
Leitra
lid
light vehicle
LiIon battery
linear drive
Lock
Locus Map
Long distance
Luggage
luggage
M
M9
MacPherson
Maintenance
maintenance, [1]
Mango, [1], [2]
Manufacturer, [1]
manufacturer, [1]
Manufacturers
material fatigue
Maximum speed, [1], [2]
maximum speed, [1], [2], [3]
Meufl
meufl
Milan, [1], [2]
Milan 4.2
Milan GT
Minihawk
Model comparison
models, [1]
moisture, [1]
moment of inertia
Motor, [1], [2], [3], [4]
motor, [1]
Mulsanne
multi track
Multi-lane
multi-lane
multi-track, [1]
multitrack, [1], [2]
Muscle, [1]
muscle, [1], [2]
N
NACA Duct
NACA duct
NACA-Duct
Navi
navigation
negative suspension travel
Netherlands
Normalized Power, [1]
nose
number plate
O
obligation to use cycle lanes
obligation to use cycle paths, [1]
on-board network
Openstreetmap
Orca
OsmAnd
Ostfalia
out of the saddle
overrun
oversteer
P
Paintwork
Pants
pants
parking brake
patches
PCD Bolt circle
pedal crank
Pedal Reflectors
pedal reflectors, [1], [2], [3], [4], [5], [6]
pedal thread
Pedelec, [1], [2]
pedelec, [1], [2], [3], [4]
Pinion
pinion
Pinlock, [1]
pinlock
plywood
pothole, [1]
Power meter
power meter, [1]
power peaks
Price
Propulsion losses
pulling side, [1]
Puncture
Q
Q-factor
Quatrevelo, [1]
Quattrovelo, [1], [2]
Quest, [1]
R
racing
racing bike, [1]
Railway
Rain, [1]
rear
rear brake, [1]
rear derailleur, [1]
rear end
rear hub, [1]
rear light, [1], [2], [3], [4]
rear lights, [1]
Rear view mirror
rear view mirror
Rear wheel
Rear wheel steering
Rear-wheel drive
Rearview Mirror
rechargeable battery
recumbent, [1]
recuperation
repair, [1], [2], [3]
response
Reverse gear
Reynolds number, [1]
Riding experience
rigididy
Rim, [1]
rim, [1]
rim brake
rim flange
road bike
Road Traffic Act (SVG)
Robert Chung, [1]
Rohloff
roll
roll bar
roll test
Rolling Resistance, [1]
Rolling resistance, [1], [2], [3]
rolling resistance, [1], [2], [3], [4], [5], [6],
[7], [8], [9], [10], [11], [12]
rolling test, [1], [2]
roof, [1]
rotational energy
Rotovelo
route code
route planner
route planning, [1]
rumble
Rural traffic
RVV 1990
S
S-Pedelec, [1], [2]
S-pedelec, [1]
saddle
safety vest
Sail effect
Saukki
scarfing
Schlumpf
scoop
Scrub radius
scrub radius, [1], [2]
sealing milk
Seat
seat, [1], [2], [3], [4]
Seat position
seat position
seating position
second-hand price
Shift cable
shift cable
Shim
shim
shock absorber, [1]
shopping
Short distance
shoulder width
side dynamo
spoke tension
sprint
sprocket, [1], [2], [3], [4], [5], [6]
sprockets
SR3
stagnation point, [1]
stagnation pressure
stall, [1], [2]
Staudruck
steering angle, [1], [2], [3]
steering axle, [1]
Steering bridge
steering bridge, [1]
steering head angle
steering knuckle, [1], [2]
Steering lever
steering play
Steering roll radius
Stiffness
stiffness, [1], [2]
storage space
stormstrip, [1]
Strada, [1]
Straight running
straight running, [1]
straight-ahead running
strut
Side Passing Distance
silhouette
single track, [1]
single-track, [1]
skinwall
slack side, [1]
sliding friction
Smartphone
snakebite, [1], [2], [3], [4]
Snoek
Snow
solo accident
speed
speed limit
Speedometer
SPEZI
Spezialradmesse
spoke reflectors, [1], [2], [3], [4], [5]
Studded
studs
Sturmey Archer, [1]
StVO
StVO 1960
StVZO, [1]
Sunrider
Suspension, [1], [2], [3], [4]
suspension
suspension strut, [1], [2], [3]
suspension travel
sway bar
swayback
Sweat
sweating, [1], [2]
swing arm
Swingarm
swingarm
Switzerland
T
Tadpole
tadpole
tail, [1]
tail light
Taillight
tailwind
Tandem
tank steering
tarpaulin
temperature, [1], [2]
tension strand
Test drive
The icing on the cake
Tie Rod
Tie rod
tie rod, [1], [2]
Tiller steering
tiller steering
tilt, [1]
tilting
tilting technique
tire
tires, [1], [2]
Toe-in, [1]
toe-in, [1]
toe-in point
toe-out, [1], [2], [3]
Tomahawk
top dead centre
top speed
torsion, [1]
track
track rod, [1]
track width
tracking
tracking point
traction
Traffic Rules Ordinance (VRV)
traffic signs
trailing arm, [1], [2], [3], [4]
Trans America Bike Race
transmission
travel
troubleshooting, [1]
trousers
Tube
tube, [1]
Tubeless
sem câmara , [1] , [2] , [3]
turbulência , [1] , [2] , [3] , [4] , [5]
Círculo de viragem , [1]
círculo de viragem , [1] , [2] , [3] , [4]
Pneu
pneu
troca de pneu , [1]
remendo de contato do pneu
Pressão dos pneus
pressão dos pneus
paredes laterais do pneu
tamanho do pneu , [1]
folga do pneu
batida de pneu , [1]
desgaste dos pneus , [1]
Largura do pneu
largura do pneu , [1]
pneus , [1]
você
UCI
Reino Unido
bicicleta vertical , [1] , [2] , [3] , [4]
roda vertical
Compra usada
Radiação UV
V
vandalismo , [1]
Velayo
Fórum Velomobil
Velomobilizar
Ventilação , [1] , [2]
ventilação , [1] , [2]
telhado versátil
Velozzontal
Visualizar
Visibilidade , [1]
visibilidade , [1]
Viseira
viseira , [1] , [2] , [3]
tensão
VTS
VwV-StVO
C
Wahoo
resfriamento de água
toboágua
UAU , [1]
rodado
Wim Schermer
vento
Sensibilidade ao vento , [1]
Peças de desgaste
Peso , [1] , [2]
peso , [1]
arco da roda , [1] , [2]
ponto de contato da roda
desempenho dos discos de roda
discos de roda
Carcaça da roda
caixa de roda , [1] , [2] , [3]
motor de cubo de roda
Poço da roda , [1]
poço da roda , [1] , [2] , [3] , [4]
sensibilidade ao vento , [1]
Túnel de vento
túnel de vento , [1] , [2]
janela
limpadores de para-brisas
Inverno , [1] , [2] , [3] , [4]
inverno
pneu de inverno
Pneus de inverno
limpadores
Fúrcula
osso da sorte , [1] , [2] , [3] , [4]
distância de trabalhovoluminous, however, the space
for luggage would hardly be usable anyway, because the oily chain is there.
In the case of a one-sided swingarm, there is only one hole in the wheel well on the right side through
which dirt can penetrate into the interior. The left side remains completely closed and clean.
With a one-sided swing arm it is possible to remove the wheel without touching the sprocket and
chain. With a double-sided swing arm, it will be more difficult to disassemble the hub because there is
not much space on the sides.
Why build velomobiles from carbon fibre or fiberglass?
Fiber-reinforced plastic can withstand roughly the same amount of force as steel – but is significantly ligh-
ter. However, the fibers must always be layed in the pulling direction. So you always need parts with
relatively large diameters and smooth transitions so that the forces that occur can always be absorbed so-
mewhere by fibers under tension. This is not the case with metal, this can withstand the same amount of
force in all directions and can also be subjected to pressure.
A thin diamond frame with highly stressed parts can therefore be built from steel, carbon offers few advan-
tages, unless you build a much more voluminous frame. A velomobile, on the other hand, deals with large
areas that are lightly loaded. That would be much too heavy to build from sheet steel – but with carbon
you can build a thin, load-bearing shell, which is neverthelessis stiff enough to transmit driving forces. So
you can do without an additional supporting inner frame, the components combine both aerodynamic and
load-bearing functions.
Why curved surfaces?
Because of the rigidity. This depends, among other things, on the thickness of the material. When you
bend the material, it is stretched on the outside and compressed on the inside. The farther apart the inside
and outside are, the greater the stretch/compression can be and the stiffer the material.
This is the reason why heavily loaded components need to be built quite voluminously – a tube twice as
large is twice as thick, so it needs twice as much material and is twice as heavy. However, since the inside
and outside of the bend are twice as far apart, it is four times as stiff, or can be constructed with
correspondingly thin walls with the same stiffness and is lighter overall.
This does not only apply to closed forms such as tubes, but also to open surfaces. Bending a material in
one direction increases the thickness for a bend perpendicular to it. A 1 mm thick material that is curved
down 1 cm is therefore as stiff in the other direction as a material that is 1 cm thick. This is exactly what
makes corrugated iron or corrugated cardboard so rigid compared to the flat material. Or: If you fold a pi-
ece of pizza in the transverse direction, it no longer hangs down in the longitudinal direction, but becomes
stiffer there.
And that’s the reason why the curved surfaces of the body of a velomobile can make a significant contribu-
tion to rigidity, for example, the chain channel is a tightly curved shape in the transverse direction, and
therefore it is incredibly stiff in the longitudinal direction and can withstand the chain forces pulling in
that direction.
Why don’t many velomobiles have foot holes?
Because they are aerodynamically disadvantageous.
Because they too impair torsional rigidity, in such a velomobile either more material is needed to
acheive the same rigidity, or power transmission is less efficient.
Because dirt, water and winter snow can penetrate from below.
Glass dome or motorcycle visor?
Admittedly, a rolling egg with a glass dome looks very chic, and from inside you have a much nicer panora-
mic view than from inside a dark, closed velomobile with small window openings in the :term`hood`. But
in the rain, cold and dark it has massive disadvantages, because the raindrops worsen the view, especially
with oncoming headlights, and such a window also mists up. You have all that with a motorcycle visor too
of course, but the area you have to keep clear is much smaller. You can also easily replace a visor if it is
scratched after wiping it too much. A visor is also relatively vertical compared to looking through a glass
dome at a much flatter angle. These problems can be solved in cars, namely with a powerful fan and thou-
sands of watts of engine waste heat and large windshield wipers. Ultimately, such a velomobile is more of a
fair weather vehicle. But it shouldn’t be too sunny either, because otherwise it heats up under the glass
dome like in a greenhouse.
Do you see enough with a hood and their tiny windows?
Actually you do.
Of course, you have a much smaller field of vision than if you were driving in convertible mode, overhead
the view is of course completely restricted. But you can see enough to the front and to the sides – about as
much as in a car. After all, you sit a lot closer to the windows so that they offer the same angle of view, even
though they are smaller. And 95% of the time you just have to look through the front visor to see traffic,
only at intersections do you need to look over your shoulders to the side. With rear view mirrors you can
see the traffic behind you.
Steering
Tank steering or Tiller steering?
This is largely a matter of taste, but both mechanisms have advantages and disadvantages: **
With the tiller steering , the position of the hands is flexible, you can steer no matter where you hold
the handlebar.
The position of the tank steering lever is fixed, some prefer this because it allows them more precise
and quicker control, which is particularly interesting in races.
Since tank steering is often very sensitive, tiny finger movements are sufficient. However, the arms
need to be supported for this. Armrests must be fitted so that every bump does not lead to an
involuntary steering movement.
With a Tiller mechanically coupled brake levers are easy to implement – the brake levers are next to
each other anyway and only need to be connected. With tank steering you can only install hydraulic
brakes and couple the hydraulic hoses, and then you would need a fallback so that a hydraulic leak
does not lead to the failure of both brakes.
For this reason, good-natured steering is necessary for tank steering, i.e. without or with negative
scrub radius. With a Tiller, you either have coupled brake levers anyway, or at least can operate the in-
dividual brake levers together, so you have much more predictable behavior.
With a Tiller the arms are higher up, which means that in hot weather you can hang your arms out of
the cockpit in a double manta position and still steer with them. This is completely impossible with
tank steering, because at least one hand must be down on the steering lever and you would have to sit
wrongly to bring the other hand up.
With tank steering, the arms must be next to the body, this space cannot be used for luggage. With a
tiller, the elbows are much higher.
When it comes to tank steering, the braking and shift cables are shorter and thus there is less friction.
With tank steering, the upper body is better ventilated because the hands are not in front of it.
A Tiller is mechanically more complicated, with a universal joint on the steering bridge and a split tie
rod.
The tank steering tie rod is not for steering, the steering levers are directly connected to the steering
knuckles so the tie rod only couples the two wheels.
With tank steering, holes are required at the bottom of the steering lever through which water can
drain when driving through a deep puddle.
Why is there no rear steering?
Rear wheel steering is more difficult to control. When cornering the centrifugal force pulls the vehicle to
the outside of the curve. Front wheel steering steers the front wheels towards the inside of the bend, i.e.
both forces act in opposite directions, the vehicle must be actively steered into the bend. With rear wheel
steering it is the other way around, to go into the curve, it has to swing the tailoutwards, and as the centri-
fugal force increases and it is drawn outwards – it tends to oversteer. Countermeasures are therefore nee-
ded to retain control at high speeds. Example: The kleine Schwarze by Harald Winkler has a coun-
terweight that is pulled outwards by centrifugal force in the curve and straightens the steering.
What’s the deal with the scrub radius?
In the case of a single-track, the front wheel is located in the longitudinal axis of the bicycle and the stee-
ring bearing above the front wheel, i.e. the steering axis goes through the wheel. This is not necessarily the
case with a velomobile: since the front wheels are suspended on one side, and it is not like a steering bea-
ring at all, the steering axis does not necessarily go through the front wheel, but hits the ground next to it.
So if you turn the steering, the front wheel does not turn on the spot, but rolls on a circular path around
the intersection between the steering axis and the road. And the radius of this circular path is the scrub ra-
dius. Incidentally, this can be positive or negative:
If the steering axis runs next to the front wheel, i.e. points to a point inside the front wheel, then one
speaks of a positive scrub radius.
If the steering axle is at an angle so that its extension goes through the front wheel and hits the ground
on the outside, this is called a negative scrub radius.
The scrub radius is important when braking: when a front wheel brakes, it pulls the shock absorber
backwards – not directly, but tangentially via a lever, the length of which is the scrub radius. This lever
creates torque on the shock absorber. If the scrub radius is positive, the wheel pulls the shock absorber on
the outside backwards – this steers the wheel outwards, i.e. the velomobile moves in the direction in which
the brakes are applied. If the steering wheel radius is negative, it is the other way round, the front wheel
steers inwards, the velomobile drives in the direction in which the brakes are not applied.
Now which is better? Ideally, the velomobile behaves neutrally and does not steer when braking. However,
one-sided braking always ensures a change of direction even without a scrub radius – the braked wheel co-
vers a shorter distance, so it is the inside of the curve. Therefore, one tends to have a slightly negative
scrub radius, which has the opposite effect, and thus compensates for the behavior mentioned.
Where is the steering axis with a MacPherson strut?
It is not so easy to say. At first glance, the suspension strut rotates around itself when steering. But this
only applies to the upper end: the suspension strut is attached to the wheel well, and rotates around this
attachment point. On the other hand, there is no fixed pivot at the bottom.
The suspension strut is held at the bottom by trailing arm and wishbone (see: What are the names of all
the parts on the chassis?), And this results in a virtual pivot point. However, this is not fixed, but changes
somewhat with the steering angle, it is roughly where the extension of the trailing arms and wishbones
would cross. And so it is also possible that the pivot point is somewhere between the spokes or even out-
side next to the wheel, although the shock absorber and the steering knuckle are completely inside next to
it.
You can have a negative scrub radius by making the angle between the trailing arm and wishbone smaller.
Here’s an example:
The trailing arm is not attached to the front of the wheel well so that it would be approximately parallel
to the longitudinal axis of the vehicle, but inside the wheel well so that it runs obliquely outwards.
The steering knuckle is extended to the front and the trailing arm shortened so that it hits the steering
knuckle less parallel.
What is caster and what is its function?
With a conventional bicycle headset, bearings are usually not vertical. This so-called steering head angle is
usually around 70 °, i.e. the head tube points 20 ° forward. The tracking point is accordingly in front of the
front wheel. This results in self straightening torque – the front wheel is pulled behind the steering axle,
which means that the steering adjusts itself automatically. The larger the caster, i.e. the distance between
tracking point and wheel contact patch, the more pronounced is this behavior.
This behavior has an important function for a single-tracker: If the bicycle tilts to the side (i.e. the cente of
gravity moves to the side) while driving slowly, it automatically steers in this direction, i.e. the wheel mo-
ves under the cente of gravity again and thus counteracts the tipping. Cornering and inclination are thus
inseparable – with a lean you can trigger cornering (e.g. when driving or pushing hands-free), and due to
the unstable position of the cente of gravity (the steering head bearing is the highest above the ground), a
steering lock also leads to opposite tilting.
With multiple track is it is fundamentally different, the steering and inclination are completely decoupled
there – cornering does not push the cente of gravity back into the cente, but it always stays the same, so it
does not trigger turning. The caster is therefore ineffective when driving slowly. When cornering quickly,
there is at least the centrifugal force to which the caster reacts, the caster simply counteracts any fast cor-
nering. A velomobile can lean very well – namely if it tips over when cornering at high speed. Then the
wheel on the inside of the curve lifts and the velomobile becomes a single-tracker – but only when it is til-
ted so far that the cente of gravity is beyond the wheel on the outside of the curve does the weight also con-
tribute to counter-steering.
Thus caster in the velomobile could at least improve straight-ahead running at high speeds. But firstly, the
space in the wheel well is limited, you can only slightly tilt the shock absorber. Secondly, the steering on a
tadpole multi-track cannot turn as freely as on a single-track, because the entire steering linkage (i.e. stee-
ring lever or tiller) still has to be moved, which would require more power or would require more caster.
The caster is also relevant for external forces. For example, it is the reason why you can push a two-whee-
ler on the saddle and steer it by tipping it sideways. But wind is also a side force, especially with the velo-
mobile with its large lateral contact surface. When the latter pushes the velomobile to the side, the caster
ensures that the wheels turn in accordingly, that improves straight-line running but it increases wind
sensitivity.
What about the Ackermann Condition?
When driving straight ahead, all wheels of a multi-lane vehicle are parallel. It’s different in a curve, be-
cause not all wheels are the same distance from the cente of the curve, they have to drive on different nar-
row circular arcs, the inside wheel must be turned more than the outside wheel. This is done by a so-called
steering trapeze – the tie rod is shorter than the distance between the pivot points of the front wheels.
Ultimately, the extensions of all axis must intersect at one point when cornering. If this is not the case, the
wheels scrub on the road.
This is not a big problem with velomobiles, as tight bends only make up a negligible part of the total
distance.
M
Fig. 9 : Ackermann condition: In a curve, all wheels steer around a common
cente. (Source:)
https://cmoder.gitlab.io/velomobil-grundwissen/_images/Ackermann_radius_M_nebeneinander.svg
https://cmoder.gitlab.io/velomobil-grundwissen/_images/Ackermann_radius_M_nebeneinander.svg
https://commons.wikimedia.org/wiki/File:Ackermann_radius_M.svg
Chassis
Why are the front wheels at an angle? Doesn’t that slow
you down?
Of course it does. Imagine that a wheel is extremely sloped, almost horizontal – it would almost no longer
roll, but would rub against the tyre flanks tangentially to the rim.
However, smooth running is not the only goal. Another is to achieve the largest possible track width – this
meansthat the velomobile does not tip over so easily and you can drive through curves faster. A wide velo-
mobile would have a larger cross-sectional area. While the space in the middle is needed to accommodate
the driver’s legs as well as the shock absorber, drum brake and hub, significantly less space is needed be-
low and above. If the wheels now provide negative camber, with the same hub spacing, you get a larger
track width and a smaller width at the top, i.e. the Velomobile is narrower at the top (= less air resistance)
and wider at the bottom (= higher cornering speed), and you can get this with a little more rolling resis-
tance. For this reason, in most velomobiles, the axles of the front wheels are not perpendicular to the
struts, but at an angle of 86°, that tilts the wheels closer to the strut at the top. However, the negative cam-
ber does not have to be 4°, and the struts themselves do not have to be vertical. Their angle depends on the
setting of the tie rod, trailing arm and wishbone.
What are the names of the chassis parts?
How this looks in reality can be seen in the next picture.
Fig. 10 : Sketch of the left front wheel (top view)
How it looks in reality can bee seen in Fig. 11.
The velomobile is shown in gray on the sketch, the wheel in black. Direction of travel: to the right.
The trailing arm is shown in green, it is usually screwed to the front of the wheel well. Together with
the wishbone, it guides the steering knuckle. The dashed line shows how it can move (the steering
knuckle and wishbone must follow the movement).
The wishbone is shown in blue, it is typically attached in the middle of the vehicle under the steering
bridge. The radius of movement also shown as a dashed line.
The tie rod is shown in red, it connects the steering knuckles of both front wheels, and the tiller may be
attached to it. The track is adjusted by changing the length of the tie rod, see: How do you know if
tracking is set correctly?
The steering knuckle is shown in orange, it is located at the lower end of the shock absorber, and the
three steering linkages above are attached to it on ball ends. Since their distance is constant, the rota-
tion of the steering knuckle is determined by the fact that the attachment points of the trailing and
transverse links can only move along the dashed lines. See: Where is the steering axis with a
MacPherson strut?
With tank steering, the rods leading to the tank steering levers are attached to the rear of the steering
knuckle.
Fig. 11 : Steering linkage on a Mango (view from the front on the underside,
parts removed and placed on the outside of the body in the appropriate places).
From front to rear: trailing arm, wishbone, tie rod (in two parts and connected
to a Tiller)
Toe-in, toe-out – which is correct?
Absolutely none. The wheels should be completely parallel. Anything else increases rolling resistance and
above all tyre wear.
Cars sometimes use a slight toe-in or toe-out, You can afford that because the tyres are less sensitive and
the engine has enough power. The advantages:
Steering play: A worn steering with play can flutter. A slight toe-in or toe-out forces the steering into a
fixed position.
Turn in: In the curve, the weight shifts to the outer wheels. A toe-in on the front wheel supports the
steering accordingly, because the loaded outer wheel then turns a little in the straight-ahead position,
and the opposite influence of the inner wheel is reduced because it is relieved.
The situation is reversed on the rear wheel, here a toe-in supports the steering. However, this then le-
ads to oversteer – when cornering, weight is shifted to the outer wheel, this steers further outwards th-
rough the toe-in, which increases the steering movement and brings even more weight to the outer
wheel.
The driving force has an effect on the track, For example, a slight toe-in for driven rear wheels or a
slight toe-in for driven front wheels can ensure that the wheels stay parallel under load.
With velomobiles, on the other hand, it is really only the rolling resistance that is interesting and here it
depends on how the track is under load and in motion:
https://cmoder.gitlab.io/velomobil-grundwissen/_images/Lenkplatte_Querlenker_Laengslenker_Spurstange.svg
https://cmoder.gitlab.io/velomobil-grundwissen/_images/Lenkplatte_Querlenker_Laengslenker_Spurstange.svg
https://cmoder.gitlab.io/velomobil-grundwissen/_images/Lenkgestaenge-Mango.jpg
https://cmoder.gitlab.io/velomobil-grundwissen/_images/Lenkgestaenge-Mango.jpg
On some velomobiles the toe changes due to bump steer see: What is “Bump Steer”?.
The wheels have a camber (see: Why are the front wheels at an angle? Doesn’t that slow you down?),
which corresponds to toe-in/toe-out perpendicular to the direction of travel. So if the velomobile tilts
around the transverse axis, for example because of a change in tyre size or suspension, the camber be-
comes a slight toe-in or toe-out, which has to be corrected by means of toe adjustment.
For example, it may be necessary to set a slight toe-in when the vehicle is stationary so that the wheels roll
optimally. Therefore, always take measurements with the driver and the load, and only after you have rol-
led a bit.
How do you know if tracking is set correctly?
If the front tyres after a few 100 km are worn out, the track was set incorrectly.
But the track can be measured relatively easily. Two approaches have proven their worth:
Measuring the position of the wheels: There are various methods, for example, place two slats on the
inside of the wheels and measure their distance at the front and rear, or attach a laser pointer to the
hubs. It is advisable to sit in the velomobile during the measurement and have it read by a second per-
son so that the chassis is loaded just as it is while driving. The wheels must be as parallel as possible.
Roll test: You roll down with the Velomobile and different settings of the tie rod and measure how far
you can get. It is important here that the starting point is always identical and the surface is as smooth
as possible (e.g. without potholes) and straight (without curves). The route does not have to be long,
for example, you can roll off a ramp that is only a few centimeters high in an underground garage or
cellar.
In a roll test, the distances of the best settings are quite close, the worse the track is set, the more the rolled
distances deviate from each other.
What is “Bump Steer”?
The suspension reacts to uneven surfaces, i.e. the front wheel moves up and down relative to the vehicle,
and with it the wishbone. This is attached to the vehicle on the other side, i.e. the end of the wishbone atta-
ched to the front wheel scribes a circular path. If it is not nearly horizontal and/or is not very long, then
this movement also has a noteworthy lateral component – i.e. the front wheel is pulled closer to the vehicle
or pushed away. And there the control arm does not necessarily run in the direction of the virtual pivot
point, which leads to a slight steering movement.
Ideally however, the wishbone is as long as possible and is as horizontal as possible in the loaded condi-
tion. In addition, the tie rod is ideally divided so that the parts are as long as the wishbones and are as ho-
rizontal as possible. A steering movement can thus be prevented during compression and rebound.
How should the suspension be adjusted?
When the wheel wells are open, the shock absorber should be inclined so that the wheel is flush with
the edge of the wheel arch.
The scrub radius should be slightly negative (see: What’s the deal with the scrub radius?).
The tracking should be neutral, i.e. the wheels are parallel (apart from the camber, see Toe-in, toe-out
– which is correct?).
The wishbones are as long as possible and as horizontal as possible when the vehicle is loaded (see:
What is “Bump Steer”? ).
The Ackermann condition is fulfilled (see: What is the Ackermann condition? ).
The steering is ideally set in such a way that it is insensitivenear the neutral position, because even
small steering movements have a big impact at high speeds. In contrast, the steering can react more in
the event of full steering locks, since these only occur when driving slowly.
Why is good straight-line stability not sufficient when it is
windy?
Some drivers are surprised that their vehicle, which is normally very well behaved and runs like on rails
even at high speeds, is noticeably deflected by gusts of wind. The reason for this is:
The straight running is mainly determined by the chassis – i.e., among other things, by the steering
linkage and wheelbase (see: What’s the deal with the scrub radius? and How should the suspension be
adjusted?).
Wind sensitivity, on the other hand, also depends on the body shape (see: How can wind sensitivity be
reduced?).
So basically they are two different things, a track-stable vehicle is not necessarily insensitive to gusts of
wind, and a wind-insensitive vehicle does not necessarily have good straight-line stability.
Wheels and tyres
Which wheel size?
The front wheels are simple: 406 mm (according to ETRTO; corresponds to 20 inches). All other sizes of
small wheels are much more unusual, and the choice of tyres and rims is correspondingly small. Only 16
inches (349 mm and 305 mm) are still reasonably common, but would not bring any real advantages. A
few hobbyists have built smaller wheels for their 20-inch velomobiles in order to fit wider tyres (e.g. winter
tyres to accommodate spikes), but this is only necessary if the space in the wheel well is limited.
With the rear wheel you have more choice, with many velomobiles possible sizes are:
559 mm (26 inch, mountain bike)
571 mm (27 inches, triathlon)
584 mm (27.5 inches)
622 mm (28 inch, racing bike)
The influence on development is rather small and can be matched by using suitable chainrings. Therefore,
the most important criterion is the size of the best tyres. The fastest tyres are basically for racing bikes (i.e.
622 mm), but they are quite narrow (and wide ones also often do not fit in the wheel well). For mountain
bikes there are also a lot of tyres, but almost only wide and with studs. Narrow, fast tyres in 559 mm are
less and less common, so the best compromise (fast, not too narrow tyres) could be 584 mm.
Why use such wide rims in a velomobile?
The rim width depends on the tyre width:
Too narrow: the tyre does not hold properly on the rim because it is not vertical to the rim flange (i.e.
orthogonal to the pressure direction), but spreads outwards. In addition, the tread is far from the rim,
i.e. side forces pull a larger lever force on the rim flange.
Too wide: the tread is close to the rim, which means that the tyre cannot deflect sideways very much
and will run faster. If the tube is squeezed, it gets the classic snakebite holes.
Snakebites are not a big problem in the Velomobile because the weight is distributed over an additional
wheel. In addition, you typically drive on smooth roads and not over curbs and stones. On the other hand,
lateral forces in curves are a big problem – since you don’t lean in the curve, the forces do not always only
act perpendicular to the tread, but often also from the side. Therefore one tends to use wide rims. With
open wheel wells, they also have the advantage that the tyre does not protrude as far over the rim, i.e. the
profile is smoother and therefore more aerodynamic.
What tyre width?
The tyre width is limited by the size of the wheel wells and even if a wide tyre would basically fit in on the
front wheels, that often reduces steering angle, i.e. the circumference becomes significantly larger.
Otherwise, the weight is distributed over at least three tyres, i.e. a single wheel has to withstand less load
than with a conventional bicycle. So there is nothing to be said against very narrow tyres, which are more
prone to snakebites. But since the tyres run inside the wheel wells, a narrow tyre is not necessary good for
aerodynamic reasons.
Ultimately, you want tyres that are as fast as possible, and that seems to be the best with a width of approx.
28 mm. But that also depends on the condition of the road – on bad roads, wide tyres that have higher rol-
ling resistance than the narrow racing tyres, can still be faster because there are fewer vibrations.
What tyre pressure?
In principle, the minimum and maximum pressures specified by the manufacturer are useful points of re-
ference. But it also depends on the following things:
Suspension travel of the tyre: A wider tyre is also taller, i.e. has more suspension travel. To avoid a
snakebite, a narrow tyre must be inflated harder so that it does not sag despite low spring travel.
Tyre spring stiffness: A wide tyre will bounce less than a narrow tyre at the same pressure and load, i.e.
to achieve the same spring travel as a narrow tyre, a wide tyre must be ridden with less pressure. (It
goes with this that a wider tyre can also withstand less pressure, see: What about Barlow’s formula?)
Load: The higher the system weight, the higher the pressure must be so that the tyre deflects the same
as with a lower load.
Number of wheels: A velomobile is heavier than other bicycles, but it also has more wheels. The load
per wheel is therefore lower and the tyre deforms less – the pressure can therefore be lower.
Lateral forces: Since a multi-track does not tilt into a curve, the forces do not only act radially, but
there are also strong lateral forces. If the pressure is too low, the tyre can deform strongly sideways,
which in the long run damages the tyre or in extreme cases pulls the tyre off the rim. Therefore, even
with little load and wide tyres, the pressure must not be too low to keep the tyre securely on the rim.
How high should the pressure be then?
The higher the pressure, the less the tyre deforms, this flexing work costs energy, i.e. high pressure re-
duces rolling resistance. However, this effect decreases with increasing pressure, if a hard tyre hardly
deforms at all, then even more pressure can only reduce the deformation very little further (see Fig.
12).
If the tyre does not have any spring at all, then not only the tyre is deflected in the event of bumps, but
the entire vehicle with the rider. This of course costs much more energy, because this acceleration can
hardly be converted back into propulsion and is lost (see: Do you need suspension? and Doesn’t sus-
pension cost valuable energy?). This speaks for a lower pressure.
For the lowest possible rolling resistance, a high pressure is therefore generally recommended, but low
enough so that the tyre’s suspension travel swallows the high-frequency bumps of a rough road, where the
suspension does not yet respond, instead of jolting the vehicle and driver. Here, a flexible tyre (i.e. thin-
walled, soft rubber compound, thin tube or latex tube or tubeless) is at an advantage because it not only
causes less loss when deformed, but also adapts better to the bumps or a lower air pressure costs less extra
power (see: Fig. 22).
Fig. 12 : Histogram of the rolling resistance of road bike tyres at different pres-
sures, measured on a roller dynamometer. The median value drops from 19.6 W
at 4.1 bar to 14.2 W at 8.3 bar, as can be seen, an increase to 5.5 bar improves
the median by a full 3 W, but further increases improve it less and less.
How good are latex tubes?
Latex tubes are more flexible than butyl tubes and therefore reduce rolling resistance (see: How do you re-
duce rolling resistance? and Why are good tyres so important on a velomobile?). According to a measu-
rement, the rolling resistance of fast tyres (Continental GP 5000) is 20% lower than that of thin butyl tu-
bes. With slow tyres the effect should be lower, with low temperatures higher.
On the other hand, latex tubes are not as tight, you have to pump them up more often than with butyl tu-
bes. In addition, latex tubes stretch more at certain points and become much thinner at these points. The-
refore, latex tubes have to fit thetyre size exactly, you have to be more careful when fitting them than with
butyl tubes (the tubes have to fit absolutely evenly), and small damages in the casing are more critical be-
cause latex tubes already swell outwards through small holes in the carcass and then burst. On the other
hand, small punctures are less of a problem, at low pressure they close up again and it takes longer for the
tyre to go completely flat. However, it is correspondingly difficult to find and patch such tiny punctures.
What is tubeless?
Normally, a tire only provides grip on the road and absorbs the resulting forces with its carcass; airtight-
ness is ensured by a tube inside. With a tubeless wheel you do without the tube, as the tire is made airtight
and also sits particularly firmly on the rim. This has a flat rim base and often also Humps to fix the tire
better; In addition, a special rim tape seals the rim base airtight. The valve is screwed directly into the rim.
A sealing milk is usually also added to the tires to seal small leaks. This brings the following advantages:
By doing without the tube, rolling resistance is reduced and driving comfort is increased (compared to
butyl).
Compared to latex tubes, rolling resistance is similar or slightly lower.
You usually have to pump air less often than with latex tubes.
In addition, lower pressures are possible because no Snakebite can occur, which is why tubeless first
became popular in the mountain bike sector.
In contrast to tubes, a tire does not burst suddenly, but the air loss occurs more slowly and is often
stopped by the sealing milk, so that the tire often does not go completely flat, but retains a small resi-
dual pressure. This increases security.
But repair is more difficult:
Small holes can often be sealed with the sealant. However, this often only works up to a certain pres-
sure - until a proper repair is carried out, you have to drive with reduced pressure, but at least you can
make progress.
Slightly larger holes can be partially sealed with a tubeless repair kit by stuffing rubber strips into the
hole with a special tool. The sealant does the rest.
For bigger punctures you have to remove the tire. This is more difficult because a tubeless tire sits
tighter on the rim. Inside, you first have to clean the tire from the sealing milk before you can stick on
a patch or insert a tube.
In the event of a total loss of air, you need a compressor or pressure tank to inflate the tire sufficiently
quickly until it is tight against the rim. Otherwise you have to use a tube.
What about Barlow’s formula?
It’s actually quite simple: pressure is force per surface, i.e. if the inner surface of the tyre is larger, a higher
force acts on the tyre at the same pressure.
If a tyre is twice as wide, then it is approximately twice as high, i.e. the circumference of the tyre cross-sec-
tion is also twice as large. Since the circumference of the wheel is almost the same, the inside of the tyre
has twice the area – so double the tensile force acts on the carcass of the tyre.
That is why wide tyres can withstand much less pressure than narrow tyres. But wide tyres also need less
pressure because, firstly, the tyre contact patch is wider – therefore, with the same load and pressure, the
contact patch is shorter, i.e. you need less pressure so that the tyre contact patch is as short as a narrow
tyre. Secondly, a wide tyre is taller, i.e. it has a lot more travel until there is a puncture (“snakebite”).
https://cmoder.gitlab.io/velomobil-grundwissen/_images/bicyclerollingresistance_hist_all_en.svg
https://cmoder.gitlab.io/velomobil-grundwissen/_images/bicyclerollingresistance_hist_all_en.svg
https://www.bicyclerollingresistance.com/the-test
https://www.aero-coach.co.uk/inner-tube-rolling-resistance
https://www.aero-coach.co.uk/inner-tube-rolling-resistance
Of course, you could build a wide tyre correspondingly more solid so that it can withstand more pressure.
But this also makes it stiffer, i.e. the rolling resistance increases – which you actually want to reduce with
higher pressure. But high pressure does not only make the tyre, but also the rim load greater. Lightweight
rims in particular can only withstand a certain pressure that is specified by the manufacturer, so if you fit a
wider tyre, you have to consider not only its maximum pressure, but also that of the rim (which is always
related to a specific tyre width) – corrected using the Barlow formula. If the tyre is twice as wide, you can
only load the rim with half of its maximum pressure.
Suspension
Do you need suspension?
Normally yes. The main characteristic of a velomobile is its speed. And high speed means that driving over
an obstacle and the resulting change in speed happens in a shorter time, i.e. the acceleration is higher. And
acceleration times mass is power, the former is constant, i.e. the vehicle and driver have to endure stronger
forces at higher acceleration. In addition, at high speeds there is less time to correct a change of direction
due to an obstacle. Therefore, it makes sense to first reduce the force peaks that affect the vehicle and dri-
ver with the help of suspension, and also to make the vehicle more controllable.
Another effect is added to the front wheels: since the wheels are side by side, but rarely the bumps, the
vehicle tilts around the longitudinal axis. The driver is not only accelerated up and down, but also thrown
from side to side, which can be very uncomfortable.
For the rear wheel, suspension is important for another reason: if an undamped rear wheel encounters
bumps with a suitable frequency, it can jump so much that the vehicle overturns sideways (see: Why is it
dangerous when the rear wheel slides?),
Doesn’t suspension cost valuable energy?
Yes, of course. Or rather: not the suspension, but the associated damping is nothing other than a dissipa-
tion of energy. But what would happen to the energy otherwise?
The driver has laboriously built up kinetic energy, and bumps in the road ensure that a small part of
the kinetic energy is directed in a different direction – for example, from forward to upward, the vehi-
cle is braked and lifted. But only rarely is there a suitable counter-evenness afterwards, which accele-
rates the velomobile, which is falling down again, forwards like a small ramp. So most of this energy is
lost anyway, and so it is better to destroy it specifically in the damping element instead of putting a
load on other parts of the vehicle.
With suspension, ideally only the unsprung part of the vehicle is accelerated on bumps, and only its ki-
netic energy is lost. In contrast, without suspension, the entire vehicle with driver has to react to the
bump, so a much larger mass has to be accelerated – so more energy is lost. A well-responsive suspen-
sion therefore makes you faster.
A suspension costs weight, but an unsprung, fast vehicle has to be built quite a bit more massive to be
able to withstand the higher force peaks.
A suspended vehicle also offers better control through more grip (and thus higher speed becomes pos-
sible on bad sections).
Without suspension, the driver (who, after all, makes up the largest part of the total mass) is also acce-
lerated, and he also does not return the energy 1:1 to the road via the vehicle, but dampens it away via
his muscles and tendons. And that is not only unpleasant, but also strains the muscles – i.e. costs
energy that should rather be invested in propulsion.
And then there is the fear that a suspension system bobs along with the cadence and eats up part of the pe-
dalling power. Of course, this can happen in principle, but it is negligible in a well-tuned vehicle. Firstly,
the drive can be designed in such a way that the chain pull is almost perpendicular to the direction of the
suspension, and the chain passes almost through the pivot point of the swingarm joint, so that the force
component acting on the suspension is very small. This cannot be completely avoided because the sprocket
usedor even the load changes the chain line slightly, and also the leverage ratios are different in each gear.
Secondly, the rider is quite fixed in a recumbent, and the cente of gravity does not change as much as with
out of the saddle on an upright bike. Accordingly, less acceleration occurs, which is then eaten up by the
damping.
What does a good suspension have to do?
Travel: You want to go fast with a velomobile and have little ground clearance. Accordingly, you drive
mainly on the road, where there are no huge obstacles to overcome, but at worst potholes. Accordingly,
you don’t need a lot of travel. A large suspension travel would even be disadvantageous because, for exam-
ple, the wheel wells would have to be correspondingly more voluminous, which ultimately worsens the ex-
ternal dimensions and the aerodynamics. In addition, the negative spring travel must be larger, i.e. the
vehicle should be higher, which increases the tendency to tip over in bends.
Responsiveness: At high speeds, the accelerations are high, so good suspension must respond very quickly
and even with small forces. This affects above all damping. In many damping mechanisms sliding friction
occurs, which is unfavorable, because static friction must first be overcome before sliding friction. There-
fore, friction dampers or poorly constructed piston mechanisms with oil dampers are unfavorable, while
spring-damper systems that are based on bending (e.g. leaf springs), torsion (e.g. torsion element in the
joint) or compression (e.g. elastomers) do not have this problem. (they do have other disadvantages, such
as temperature dependency, or lack of adjustability of the suspension/damping characteristics.)
Strength of damping: This must be neither too strong nor too weak, as can be seen in Fig. 13, an oscillation
decays fastest when the damping corresponds to the aperiodic limit case. So both the spring stiffness must
be matched to the mass to achieve the correct rest position, and the damping must be matched to the reso-
nant frequency resulting from spring stiffness and mass. This allows the velomobile to compensate for
uneven ground as well as possible and then come to rest as quickly as possible.
Fig. 13 : Damped harmonic oscillator, with varying degrees of damping. In all
cases the oscillation decays exponentially. If the damping is too low (= oscillation
fall), the equilibrium position is reached fastest, but overshooting occurs. With
too much damping (= creep case) there is no overshooting, but the equilibrium
position is reached only slowly. In the aperiodic limit case (= critical damping)
the amplitude decays fastest because it is the lowest damping without
overshooting.
Couldn’t the suspension be replaced by low pressure wide
tyres?
Wide tyres with little pressure can be surprisingly comfortable on rough ground. But they cannot replace
real suspension:
Travel: To offer several centimetres of travel, a tyre would have to be extremely bulky – and thus
hardly lighter than a suspension, with less lateral support and a larger turning circle.
Damping: A suspension must also dampen (see: What does a good suspension have to do?) – but a
good tyre should have no damping at all, because this would eat up energy not only during bumps, but
during the deformation that occurs in every single rotation. (That’s why you can judge a tyre’s rolling
resistance by how high it bounces back when you drop it).
Adjustability: it’s much easier to adjust a suspension than a tyre – it’s relatively easy to change springs
or adjust damping without affecting travel, whereas with a tyre you can only change air pressure, the
shape and rubber compound is fixed.
In the end, it is better if a well-tuned suspension compensates for and dampens away rough bumps, and
high-frequency vibrations (with low amplitude) are swallowed by a supple tyre.
Why is it dangerous when the rear wheel slides?
It’s a combination of several things:
The front wheels do not easily lose cornering grip, because they are rarely in the air at the same time
and rarely is one suddenly in the air. It’s different with the rear wheel, if it jumps over bumps undam-
ped or if the tyre bursts, the cornering is suddenly sharply reduced.
Since the centre of gravity is much closer to the front wheels than to the rear wheel, there is little
weight on the rear wheel. Correspondingly, the cornering force is normally significantly lower than
that of the front wheels, and it is therefore easily critical if it is reduced again.
When turning, not only the load plays a role, but also the position relative to the cente of gravity: the
front wheels are almost next to the cente of gravity – they roll tangentially to a rotation about the verti-
cal axis and there is practically no resistance. The rear wheel, however, rolls radially, it opposes the
tangential movement with high resistance. If the centre of gravity is further back, the direction of the
cornering force is more favourable for the front wheels (they no longer roll tangentially to it), and the
rear wheel has more load (see Fig. 14).
With a velomobile it’s steering angle is quite small, because it is limited by the width of the wheel
wells. So if the rear wheel loses lateral grip and breaks out to the side, there are only limited counter-
measures available.
You often drive fast with a velomobile. The reaction time is correspondingly short in order to be able to
react to a rear wheel breaking out.
If for some reason the rear wheel no longer has cornering power – regardless of whether it jumps or
blocks, or a burst tyre no longer sits on the rim – and there is also lateral force – because you are driving
through a curve or it gets a side blow from a pothole – then it breaks out. And if the velomobile turns faster
than you can counteract it, it can turn sideways and roll over. This requires surprisingly little, one example
is a velomobile with an unsprung rear wheel that hits the vibrating strip in a straight line with the rear
wheel and is tipped over in just a few seconds at full speed.
What can I do about it?
Luggage to the rear: firstly increase the load on the rear wheel and secondly moves the cente of gravity
further away from the front wheels.
Check tyres: tyres rarely burst unannounced, there is usually visible pre-damage.
Use reliable tyres with a sticky rubber compound.
Tubeless rim: Makes it more difficult for the tyre to come off if it blows out.
Wide rim: Makes the tyre less tall, which means that as long as it doesn’t bounce off, it bounces less.
https://cmoder.gitlab.io/velomobil-grundwissen/_images/harmonic-oscillator_en.svg
https://cmoder.gitlab.io/velomobil-grundwissen/_images/harmonic-oscillator_en.svg
Fig. 14 : Direction of the forces on the wheels as the velomobile tilts around its
vertical axis, with different centes of gravity. Since the rear wheel is located
behind the cente of gravity, the forces are always applied perpendicularly to it
when the velomobile tilts, tracking is thus good. Green: If the cente of gravity is
further back (here: 70% of the distance between the front and rear wheels), then
there is a lot of load on the rear wheel (here: 70%), and in addition, the forces on
the front wheels are almost perpendicular to them. Red: If the cente of gravity is
further forward (here: 10% of the distance), then the forces are almost parallel to
the front wheels – so they can’t provide much lateral support. The rear wheel
can, but only 10% of the load is on it. In reality, the centre of gravity is usually lo-
cated between these extremes, somewhere near the orange point, i.e. about one
third of the distance between the front wheels and the rear wheel, and
accordingly load distribution on the wheels is relatively balanced.
https://cmoder.gitlab.io/velomobil-grundwissen/_images/schwerpunkt_spurfuehrung.svg
https://cmoder.gitlab.io/velomobil-grundwissen/_images/schwerpunkt_spurfuehrung.svg
Gears
What role do gears have to fulfill?
The challenge with velomobiles is that on the one hand you drive at