Rear Wheel Torque Equation Confusion

[willeng]

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!

 

[kazx9r]

You figure this out?

 

[Mech_Engineer]

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

 

[kazx9r]

Hey don't give him all the answers.

 

[xxChrisxx]

Why not?

: /