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Electric Bicycle with no Battery

  1. Feb 1, 2017 #1
    Hello, I am curious if this has been done, or would even be worthwhile.

    The idea would be to use a generator at the pedal and conduct the electricity directly to a wheel motor with no power storage. This would eliminate gears and a chain. Does anyone know what the approximate efficiency of such a system would be?

    How would this drive system behave when going up a steep hill? Would it act as an automatic gear reducer and vice versa when going downhill?
     
  2. jcsd
  3. Feb 1, 2017 #2

    jedishrfu

    Staff: Mentor

    I've seen similar experiments where students pedal on a bike to drive various electrical appliances and as more are added to the circuit it become difficult if not impossible to pedal because of the load.



    Here's a DIY project on it:



    Its cool but not as efficient as a straight chain drive. You can add a battery into the mix for more flexibility when you get tired of pedaling and that is the primary advantage over a straight chain drive.
     
  4. Feb 1, 2017 #3

    sophiecentaur

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    Science Advisor
    Gold Member

    absolutely. It's no surprise that the basics of the bicycle haven't changed since they introduced chain drive. With the fantastic number of ratios available on a bike, an infinitely variable gearing is hardly worth considering.
     
  5. Feb 2, 2017 #4

    CWatters

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    Science Advisor
    Homework Helper

    I would anticipate the generator and motor being 80-90% efficient at best. You would also need some sort of DC-DC converter/regulator/optimiser to replicate the effect of gears. That might be 90% efficient at best? So overall somewhere between say 55% and 70% overall? Your mileage may vary.
     
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