Originally Posted by
Leisesturm
I doubt it. 2.5mm probably just exceeds the manufacturing tolerance for all but the best of the best components. Your cranks are mismatched by that much right now and you don't even notice. And as long as I am here I will observe that the 2.94% loss of torque going to the shorter cranks is not easily compensated for by downshifting since few clusters have less than a 9% change between gears. It's even bigger at the extremes. Seems to me that headwinds and climbing are the places where one would be least likely to want shorter cranks.
Even cranks 100 years old do not have that kind of variance. Ask me how I know.
The issue here is torque of course- and with longer cranks you have more torque. But since the issue is torque, how much torque can your knees handle before they cause you to stop riding? When you run shorter cranks, its easier to spin faster, so when confronted with a headwind or hill you might have to gear down a bit. I've gone from 175s to 170s and not found that I had to mess with the gearing on the bike. If you went to 155s its likely a different matter.