Originally Posted by
phughes
I'm your height and prefer 172.5 cranks. I swapped the 175s on my Long Haul Trucker for the 172.5s and much prefer them. Despite how close they are, they definitely made a difference. I would not mind trying 170s, but for now, the 172.5s feel nice. I can spin more freely.
A 2.5MM difference in crank arm length is damn near going to make no difference. You'd notice more of a difference upgrading to a higher quality, lighter crankset or even changing out your gearing.
Crank arms need to be proportionate to your inseam and how much power you output.