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Need help with a tri-cycle design

  1. Jun 29, 2015 #1
    That is in a tandem cycle where one set of pedals go to the front and the other to the back. So it's an all wheel drive, but when two people ride it, how do you prevent relative slip due to difference in pedalling?
    Any help would be very much appreciated.
     
  2. jcsd
  3. Jun 29, 2015 #2
    Or even in a cycle with three wheels with each front and rear wheels being driven be different people???
     
  4. Jun 30, 2015 #3
    I'm designing a two person tri-cycle where one person drives the two wheels in the front and the person in the back drives the single rear wheel by pedalling. The problem I have now is that I can't figure how I will prevent the relative slip that may occur due to the difference in pedalling speeds of both the cyclists.

    This design is for a competition and it's really essential that I solve this problem. Any help would be much appreciated.
     
  5. Jun 30, 2015 #4

    jedishrfu

    Staff: Mentor

    Well a high-tech solution would be to have each cyclist power a generator and the two generators charge a battery that is used to power the motor.

    Don't most bikes use a hub that allows you to coast so you could use one on each axle. If your trike is going faster than you're pedaling then it feels effortless but won't impede the other cyclist doing the work.
     
  6. Jun 30, 2015 #5

    berkeman

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    Staff: Mentor

    That's not how most tandem bicycles work. The wikipedia article has a section on drive trains that may help you out...

    https://en.wikipedia.org/wiki/Tandem_bicycle

    :smile:
     
  7. Jun 30, 2015 #6
    I would look closely at a "DaVinci" bike. They are a Tandem bicycle that allows each of the two riders to contribute while allowing independent pedal Cadences. They have proven to be a little challenging mechanically for the average bicyclist. There is a defined advantage in having asynchronous drive as the harmonics of synchronous pedals are severe in normal tandems.

    Aside from some type of floating hub. The easy approach is to rely on rider control to each be applying pressure. What kind of budget do you have? If you could incorporate modern power metering bottom brackets There could be a visual reference for each rider to see if they are keeping up. (or much worse tell your partner how much you are not contributing. oops)
     
  8. Sep 15, 2015 #7
    use the front guy only to handle the tri-cycle and the give the rear ones a single axled peddal and this axle bears the 2 rear wheels and this gives no slip.and this helps in reducing the effort of each on the ride.
     
  9. Sep 19, 2015 #8

    JBA

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    Can you post a picture of your bike. I am interested in how the front pedal assembly delivers it power to the front wheels/axle while allowing the front wheels to be turned to steer the bike. The primary issue is whether or not both the front and rear pedal assemblies remain fixed in positon and aligned when the bike is turned. Depending on that, I may have a suggestion.
     
  10. Sep 21, 2015 #9

    jim hardy

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    Science Advisor
    Gold Member
    2016 Award

    i'm confused.

    slip between what and what else?

    Seems to me friction with the ground will prevent slip
    unless one of the cyclists has legs so strong he can spin the tyres
    and i don't see why that would matter.
     
  11. Sep 21, 2015 #10

    JBA

    User Avatar

    It may be intended as a all wheel drive bike for off-road and trail riding on dirt, sand, rock, mud and other slippery conditions. As a hiker, I have sometimes wished I had two more legs for those conditions as well.
     
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