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Bicycle gearing

  1. Mar 30, 2016 #1
    I have put together a tricycle, but it only allows for a 4in sprocket on the axel. I have added a motor to the tricycle and do not get enough torque. The motor came with a 6in sprocket, which will not fit on the axil.
    My idea is to set it up so the chain goes from the motor 1in to the 6in to the 4in in one continuous loop. WILL this get me the torque I should be getting?
    Last edited: Mar 30, 2016
  2. jcsd
  3. Mar 30, 2016 #2


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    Staff: Mentor

    Welcome to the PF.

    Can you use the UPLOAD button at the lower right to post a couple pictures of what you are trying to do? :smile:
  4. Mar 30, 2016 #3
    here is the bicycle basic drawing.

    Attached Files:

  5. Mar 30, 2016 #4
    This configuration will not gain you the torque that you are looking for. The 6" gear in the center appears to be acting as a large idler. To increase the torque you would need to run from the small gear at the right side of your drawing to a larger one on the "idler shaft" this would then create a reduction gear of sorts. Than on the same idler shaft have a parallel smaller gear which is connected to the final shaft on the left side of the drawing.
    To do the calculation on this one needs to take each pair independently first and then calculate the final ratio using the two reductions.
  6. Apr 1, 2016 #5
    Thanks I rather figured that's the way it would be.
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