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Rear Wheel Torque Equations

  1. Jun 4, 2012 #1
    I found some differing equations on the internet than what I thought on how to arrive at the rear wheel torque value for Motorcycles, so I thought I had better ask here to make sure.
    One site said Rear Wheel Torque = Chain Tension X Tooth Count Ratio (front & rear sprockets)
    I was under the impression that the formula was:
    Rear Wheel Torque = Chain Tension X (Rear Sprocket Pitch Radius/Front Sprocket Pitch Radius)
    At first I thought both would work out the same but after measuring some things & doing the numbers there is quite a difference in the final outcome.

    Not sure now what to think?

    Any help would be appreciated!
  2. jcsd
  3. Jun 8, 2012 #2
    You figure this out?
  4. Jun 8, 2012 #3


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    Science Advisor
    Gold Member

    The answer is easy, since the pitch diameter and tooth count can both be used to find the reduction ratio:

    Rear Sprocket Pitch Radius / Front Sprocket Pitch Radius
    Rear Procket Tooth Count / Front Sprocket Tooth Count
    Tooth Count Ratio
    Pitch Radius Ratio
    Reduction Ratio
  5. Jun 8, 2012 #4
    Hey don't give him all the answers.
  6. Jun 8, 2012 #5
    Why not?

    : /
    Last edited: Jun 8, 2012
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