Originally Posted by
AnthonyG
The problem with the notion that longer cranks give you more torque is that our legs need to travel through a 360 degree motion of muscle and joint movements, and while you may get more torque at the 9-3 position you also get less torque at the 12-6 position. Shorter cranks smooth out the torque delivery rather than reducing it.
When moving from longer cranks to shorter cranks its quite important to move your saddle BACK, as well as up in order to maximise the torque from the shorter cranks.
Its all true, only question is what's considered too short versus too long.
Longer crank arms can and often will help with better power output at more specific cadences.