Originally Posted by
dabac
But why would your riding style change that much? The hardest push from the rider is still the hardest push, and regardless of crank length I guess there's a few occasions on each ride when the drive train gets to see just that. (grinding up a hill, getting going from stop in a poorly chosen gear...)
There is a place for your scenario, but only if the rider actually do push harder with the shorter cranks, which we don't know. I don't think I would.
I understand your point; and I'd suggest you just try it, but instead I'll tell you my exact experience.
The shortest crank arms I've tried were 5" unicycle cranks (127mm) that I put on my Strida (an unusual folding bike, single speed, and front freewheel system, which is why unicycle cranks work). As it turned out, I had to replace the crank anyway, and chose the short unicycle cranks to see if they would let me spin a little faster, and maybe increase my top speed. I think it did increase my speed maybe a little, certainly not much; but I did notice that it was now much more difficult to get up to speed when starting from a stop. Somewhere around 5 to 10 mph I normally want to push really hard on the pedals, and with the short cranks that usual amount of push didn't seem to do much good. So to get up to speed, I necessarily pushed a lot harder.