Originally Posted by
parallelfish
I was addressing the notion that the same gear ratio, achieved via different spur gear sizes, can produce different torque ratios (as was stated in the previous post). I believe that I did state that there may be other reasons for preferring the use of larger gears, and cited a couple of examples.
Keeping the same ratio with different spur sizes does make a difference, mainly because you are moving the motor fore / aft. To say changing the size of the spur alone, while retaining the the ratio will make a difference on how the motor operates (torque / rpm) I believe the gains are pretty slim. Only way to prove it is on a dyno. I believe when Jonny5 said leverage, he meant moving the motor back..
Also Smaller spurs really do not reduce rotating mass as you have to change to a heavier "alloy" pinions. Not much gain there.
What are your thoughts? My .02.