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Is there any realistic, cheap way to change a car into a pedal-driven vehicle you can ride yourself?

(I'm not quite sure if this is the right category to ask, but I couldn't find a better one.)

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  • 4
    Cars are too heavy. Your should Google "rosalie" which is what 4-wheel multi-person cycles ate called in some countries (I think they may be known as "surrey"s in America). They're not practical for general use. Too wide for bike lanes and too slow for roads
    – Chris H
    Jun 6, 2017 at 7:22
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    No. Even if you strip out the engine and entire drive train, then cassis alone will be unrealistically heavy.
    – alex
    Jun 6, 2017 at 7:23
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    English wikipedia: quadricycle, more pictures if you follow the "français" link
    – Chris H
    Jun 6, 2017 at 8:03
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    I recall 40-50 years ago seeing pictures of such contraptions, built by folks who had too much time on their hands. Of no use other than as a curiosity.
    – Daniel R Hicks
    Jun 6, 2017 at 11:38
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    A Canadian artist did this years ago: micheldebroin.org/shared-propulsion-car
    – blahdiblah
    Jun 6, 2017 at 18:49

3 Answers 3

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39

No

Since that's way too short for an answer, lets look at some maths.

An average car might weigh

  • Compact car 1,354 kilograms (2,979 pounds)
  • Midsize car 1,590 kilograms (3,497 pounds)
  • Large car 1,985 kilograms (4,366 pounds)

Info from http://cars.lovetoknow.com/List_of_Car_Weights

Lets say you start with one of the lighter cars, a Daihatsu Charade gen3 from 1988-1991. This car weighs 740 to 760 kilos, or as much as 50 15 kilo bikes, or 110 UCI legal race bikes at 6.8 kilos. Source: https://en.wikipedia.org/wiki/Daihatsu_Charade

from https://en.wikipedia.org/wiki/Daihatsu_Charade

What parts can you remove and still call it a "car"

  • Engine 13%
  • Fuel system and exhaust 6%
  • Gearbox
  • Clutch
  • Differential
  • Axles
  • Air conditioner and Heater 3%
  • Power Steering
  • Electrical wiring and starter battery 3%
  • Many of the instruments 1%

So a total of 26% plus a lot of unknowns.

Percentages are according to this (admittedly ambiguous) breakdown pie chart http://www.frost.com/prod/servlet/cio/166542466

Flipping it about - how much do you need to keep? So 24% of your car is "structure" which will cover chassis. The external panels add 5%. Wheels and tyres are needed to roll, brakes to stop, that's 10%+3% Suspension can probably be lightened because of the weight drop but you'll still need half of it at 5.5%. Interior of 10% could be reduced by half to 5%. For a total of just over 50%

Lets assume you can HALVE the weight of your lightweight car by removing non-essentials. That leaves 375 kilos of dead weight that you still have to move around.

And that's simply ignoring the weight of your pedal propulsion system still to add.

Lets go one step further and assume you did all this, and end up with a 375 kilogram bike shaped like a car. Also assume you have managed to keep the 4 seats.

Using http://bikecalculator.com/ we can guessstimate your speeds.

1 rider of 75 kilos, putting down 150 watts get about 9.4 km/h on the flat with zero wind.

Same rider gets 1.9 km/h if the gradient picks up to 5%

If that single rider were on a 10 kilo road bike, they'd be getting 10.8 km/h up the same 5% grade

...OK but its a 4 seater...

4 riders of 75 kilos each doing 150 watts would get about 22.8 km/h on the flat.

Same 4 riders on the 5% hill get 5 km/h

Taking it to the extreme, 40 riders in your car each weighing 75 kilos and adding 150 Watts, would climb the same grade at 10.0 km/h, not as fast as one of their number on a 10 kilo road bike.

Turns out you need 265 cyclists in your car to match the single road bike on this simple climb. Collectively that's 20 tonnes of cyclists inside your 375 kilo stripped out car.

Why are cars so heavy? Because the kinetic energy required to drive at open road speeds needs a chassis of a certain minimum strength. And if you want that chassis to last more than one trip it has to be overbuilt which means adding strength through thickness.

Car seats are very heavy, a racing car seat might be 3 kilograms and a conventional single seat anything from 20 to 70 kilograms depending on motors and armrests. They have to hold and protect the occupant in a collision with hundreds of km/h difference in speed. Your average 500 gram bike saddle doesn't have those requirements.

Links

There are people who have gone the other way, and wrapped an enclosure around a bike rather than stripping a car down to find the bike inside.

The PodRide weighs 70 kilograms, and is a cloth and tube frame around a recumbent-style frame.

From kickstarter

http://mypodride.com/

https://momentummag.com/swedish-inventors-bike-car-winter-riding-solution/

https://www.indiegogo.com/projects/podride-a-practical-and-fun-bicycle-car-bike-bicycle--2#/

Legally its an electric bike, at least in Sweden.

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  • I love it Criggie
    – CardMechanic
    Jun 6, 2017 at 14:06
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    How did you use the Bike Calculator? It is definitely no use to just put in the mass of a car into the equation designed with a cyclist in mind. Only uphill, this can give sensible results because in the low-speed limit, drag is neglectable (which sure makes the point that a pedal-powered car is utterly useless in hilly terrain), but the frictional and particularly turbulent resistances are completely different, so in completely even terrain the point can never be relevant.
    – leftaroundabout
    Jun 6, 2017 at 16:51
  • Fully-enclosed recumbent bicycles are generally called Velomobiles. With indicator (turn) lights, they could be called pedal-powered cars. en.wikipedia.org/wiki/Velomobile
    – CSM
    Jun 6, 2017 at 16:56
  • @CSM true and totally correct, but OP's question was about converting an existing car to run on pedal power (flintstoning perhaps?) I only added the podride because it answered the implicit question of how to make a bike resemble a car.
    – Criggie ♦
    Jun 6, 2017 at 20:15
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    @leftaroundabout the CdA of a small car and a person on a bike aren't that different, and drag is linear in CdA. For these purposes so long as they're of the same order of magnitude we don't need to care.
    – Chris H
    Jun 7, 2017 at 9:42
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You did not specify the scope of your question, i.e. does something that looks like a car count? If yes it is possible.

enter image description here

You can do it by buying a four wheeled bicycle and building a lighweight (wooden? plastic pipes + tape? don't forget paint!) framework around it in the shape of any car you want.

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  • Building it out of wood is a very interesting idea. Although rain could be bad for the wood, I still like the idea
    – caylee
    Jun 6, 2017 at 17:40
  • The pedal-powered Ferrari is pretty slick too: youtube.com/watch?v=cYWhyEjp4pM
    – Jeremy Friesner
    Jun 7, 2017 at 2:38
  • @xanoetux why would wood be a bad idea? Trees live outside and they used to make ships out of wood.
    – Burgi
    Jun 7, 2017 at 9:17
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Probably a bad idea, for all the good reasons given by the other answers.

However...

Bad ideas sometimes turn into "good" ideas when beer is involved:

enter image description here

(Image credit: San Jose Mercury News)

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  • Yeah, there's one of those in our area. A little problematic when the folks get really drunk.
    – Daniel R Hicks
    Jun 7, 2017 at 0:33
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    Good point, but not really "cheap" nor a car conversion. FYI the "captain" is legally the driver, and must obey all road rules, including being under any blood alcohol limits mandated. Driver does not pedal either, but they have a drive disconnect so they can stop being pushed by a crowd of mean drunks The one in my city tends to be trailered to private property for use.
    – Criggie ♦
    Jun 7, 2017 at 6:45
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    @DavidRicherby FWIW I don't think these are a good idea at all. I meant "good" idea from the perspective of the beer drinker.
    – Digital Trauma
    Jun 7, 2017 at 15:04
  • @DigitalTrauma The inverted commas you added certainly change the message. :-)
    – David Richerby
    Jun 7, 2017 at 15:12

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