Originally Posted by
Nagrom_
I did the math in another thread long ago, and it came out to be a 3% difference in cadence gained/leverage lost when using 165's over 170's.
48/16 vs 48/18 is something like a 12% gear inch increase, so that's quite a bit more drastic.
Your point comes across, although in this case, it's definitely splitting hairs. I doubt OP could notice the difference between 165's and 170's. I bet very few could actually.
Leverage is one thing, but there is also footspeed.
Footspeed is the speed at which your foot is traveling in a circle. For a given cadence (say 100RPM) the foot must travel faster using longer cranks because the circumference of the pedal stroke is bigger. It will require less torque in the process, but the foot must travel faster.
I'll try to do the math...one sec...