Originally Posted by
Iride01
What size crank have you been riding? If you haven't been riding much, then go with what the bike comes with and then after you figure out some reasons why it's not working for you then you can change cranks and see what they do for you.
Mostly 175mm, on my road bike - simply because there was no option for a longer option. It feels OK to me, but I have no comparison except for a few minutes at 180 on the fitter’s adjustable bike.
If I get a frame with a standard BB height, then switching to much longer cranks later will likely lead to pedal strikes - so if I want longer cranks, I have to at least allow for the possibility when choosing/designing a frame.
I think it’s a given that my max cadence, and even average cadence will drop with longer cranks. I’m not sure that’s a bad thing - larger athletes/animals tend to have lower “cadences” (running, flying, whatever). Zinn’s tests indicate that his climbing speed increased noticeably with longer cranks - that would be of more value to me than spinning fast. The fitters commented that I looked a little weird pedaling on 175’s, since my feed were making such a small circle relative to my leg length, and definitely didn’t look worse at 180. I wish that I had suggested trying longer lengths at the time, but had no idea that really long cranks were even available, till I got home and started researching.