170 mm crank length

i'm a dude and i'm 5'7.5" with a long torso and short legs. why am i hanging out in the womens lounge? i don't know. saw this thread and thought i'd comment.
i had been using 175mm cranks for years basically because everyone else did. never really thought about crank length. last year i bought a new bike for diablo bike park and ordered it with 170mm cranks for ground clearance issues. didn't really plan on pedaling it too much. once i started riding it i noticed how much better i could spin with no real loss of power. also had less cramping and fatigue in my legs, even with a heavier bike. though that there had to be something to this, so i ordered a set of 170mm cranks for my cross country bike and have never looked back.
when i really thought about it, it made sense. i ride with some guys who are 6'2" with long legs and they use 175mm cranks. my legs are like half the length of theirs and i'm using the same crank length. the physics of it just didn't make sense to keep using the 175mm.

unclekittykiller said:

i'm a dude and i'm 5'7.5" with a long torso and short legs. why am i hanging out in the womens lounge? i don't know. saw this thread and thought i'd comment.
i had been using 175mm cranks for years basically because everyone else did. never really thought about crank length. last year i bought a new bike for diablo bike park and ordered it with 170mm cranks for ground clearance issues. didn't really plan on pedaling it too much. once i started riding it i noticed how much better i could spin with no real loss of power. also had less cramping and fatigue in my legs, even with a heavier bike. though that there had to be something to this, so i ordered a set of 170mm cranks for my cross country bike and have never looked back.
when i really thought about it, it made sense. i ride with some guys who are 6'2" with long legs and they use 175mm cranks. my legs are like half the length of theirs and i'm using the same crank length. the physics of it just didn't make sense to keep using the 175mm.

Click to expand...

Almost the same story for me. I'm a dude - saw the thread - wanted to comment. I'm 5-8 and 30 inch inseam. Rode 175mm all my life - because that's all you could usually get. I got a low-slung rig and wished I got shorter cranks for ground clearance. Swapped bikes with a friend this summer on a group ride and *instantly* noticed a difference in the cranks and loved them. I asked him if they were 170mm and he said yes. What I keep agonizing over is that I just bought new cranks less than 2 years ago for like $225 (and had the option to buy 170) and now I don't want to spend that again to get the *correct* length I should have bought in the first place. :madman: Some day I'll break down and buy the 170mm - I'm just too tight with my money.

To the OP - if you can try them on any bike, I would give it a try. As far as power goes, I think I calculated at one time that a gear ratio of 32:34 (middle ring, big cog on cassette) with 175mm arms was the same torque as 32:33 with 170mm arms. So, you're not likely to notice the power difference when you need it the most - on grinding climbs.