170 v 175mm cranks

[Raging_Bulls]

Here's what I came across as a general guideline

inseam < 29 inches - 165 mm crank
inseam 29 - 32 inches - 170 mm crank
inseam 32 - 34 inches - 172.5 mm crank
inseam > 34 inches - 175 mm crank

Track riders generally choose crankarms up to 5 mm shorter and mountain bikers up to 5 mm longer than the above recommendations.

 

[FairfaxPat]

I have a 34" inseam and ride 180mm cranks in the woods, and 175mm on the road. If your legs are long enough to accommodate them, longer cranks give more leverage, which I find helps when I come to the extra steep bits in the dirt.

 

[bluedazzler]

I have a 29" inside leg and ride 175mm cranks. they've never given me any problems

 

[elPedro666]

Have been playing with 170/175 recently and can definitely feel the difference, although I kinda like both! :roll:

Similar to what's been said, I've always believed you shouldn't flex your knee past 90', so not too long for your legs is the only proviso

 

[We_are_Stevo]

Personally I've always wondered if this OCD attitude towards crank lengths wasn't a complete crock'

Having read Keith Bontragers take on it in the link below I feel somewhat vindicated...

http://sheldonbrown.com/kops.html