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Crank arm size for road bike, what is the standard size?(5 posts)

Crank arm size for road bike, what is the standard size?russ g
Aug 1, 2001 7:44 PM
Having come off a mountain bike for the last few years and back into road riding on my new Bianchi it feels like my legs are spinning too short. The cranks on the Bianchi are 170mm and I think the mountain bike had 172mm which I can actually feel the diference in length quite a bit. I'm 5'10" and the bike is a size 55. For this size combination is the 170mm standard and something I should just get use to or should I try to go to a 172 as I've used on my mountain bike?
re: Crank arm size for road bike, what is the standard size?LC
Aug 1, 2001 7:51 PM
I use 175 on my mountain bike and 170 on the road, but when I am off road the last thing I am worried about is constant pedaling, more like rocks and roots and mud holes. You never gave your inseam, but you are probally between 170 and 172.5 for the road bike if you are under 33" and it is not worth changing.
Thanks for the reply, yes, I'm at 32"-33" inseam.russ g
Aug 1, 2001 8:35 PM
dependsMike K
Aug 2, 2001 9:00 AM
I'm about the same size as you, 5'10", 32" inseam. I ride a 175 MTB and 172.5 road. I think that the 172.5 for road is pretty standard for guys my size.
That said, much will depend on your preference. Longer crank arms give more leverage (which is why MTB cranks tend to run longer) but are harder to spin at a high cadence.
High cadence spinners tend to go shorter - mashers go longer.
Basically thisLardog
Aug 2, 2001 9:39 AM
Most off the rack bikes under 52cm will come stock with 170. 52-58 with 172.5 and 59cm + 175. Of course, all this will vary depending upon what the shop has around, if the bike comes to them with the build kit, etc., however, this is what has been told to me and recommended to be followed unless your application or preference lies out of the norm. Meaning, you do all climbing, or all flat, or want better acceleration or you want all top end for time trialing, etc.