Originally Posted by
sjanzeir
I've been wanting to experiment with this for a while: Running shorter crank arms than the usual 170-175-millimeter OEM ones that come on most bikes in my frame sizes (15-17.5/S-M.) Nothing wrong with some experimenting; I'm 5'3" inches/160 centimeters tall; and the Wise Oracle that is the internet says that ideally, I should be running 150-155mm cranks - which is totally ridiculous.
What was perhaps a little foolhardy on my part, though, is that I went ahead and up(down?)graded not one, but both of my folding bikes to 165mm cranks. I did not expect to be having this creeping desire to want to go back to the stock 170mm cranks.
All I expected was for there to be a subtle difference in cadence and power at worst. It turns out, the differences really were a little less subtle. Now my legs tend to spin up faster - and spin up to a significantly higher cadence they do - than I'm accustomed to, in lower gears than I'm used to, with a little less torque than I had come to expect. Simple physics; no surprise there.
It's been a week or so and I've only ridden the bikes a few times, and just around the neighborhood at that. So I should probably give them more time so as to fully figure out exactly how I feel about this and what I need to do.
In the mean time, I'd really appreciate some of your experiences with running shorter cranks!
Yeah, that's the reality with shorter cranks i.e. you have to spin more to create the same power (since power = pedal force x crank length x cadence). The advantage of shorter cranks is that you are less likely to exceed your range of comfortable joint articulation (i.e. knee extension/compression, less hip impingmement etc). So they can be good for endurance and reducing the risk of injury. But there's no free lunch here. At 5'3" I would give the shorter cranks a bit more time. 165 mm is not that short in relation to your height (presuming your legs are in typical proportion). Learning to spin faster is generally a good thing too.