Rear Wheel Torque Equation Confusion

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Discussion Overview

The discussion revolves around the calculation of rear wheel torque for motorcycles, focusing on differing equations and methods to arrive at this value. Participants explore the implications of using chain tension and various ratios related to sprocket dimensions.

Discussion Character

  • Debate/contested

Main Points Raised

  • One participant presents two equations for calculating rear wheel torque: one based on chain tension and tooth count ratio, and another based on chain tension and the ratio of sprocket pitch radii.
  • The same participant notes a significant difference in outcomes when applying these formulas, leading to confusion.
  • Another participant suggests that both pitch diameter and tooth count can be used to derive a reduction ratio, implying a relationship between the two methods presented.
  • A later reply questions the appropriateness of providing direct answers, indicating a concern for the learning process.

Areas of Agreement / Disagreement

Participants do not reach a consensus on which equation is correct or preferable, and the discussion remains unresolved with multiple competing views on the calculation methods.

Contextual Notes

The discussion highlights potential limitations in understanding the relationship between pitch radius and tooth count, as well as the assumptions underlying each proposed equation.

Who May Find This Useful

Individuals interested in motorcycle mechanics, torque calculations, or those studying mechanical engineering principles may find this discussion relevant.

willeng
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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!
 
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You figure this out?
 
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
 
Hey don't give him all the answers.
 
Why not?

: /
 
Last edited:

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