Crank Arm Length

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6 replies [Last post]
Anonymous's picture

"Can anybody help me determine the correct crank arm lenth for me? I am 6'4"", about a 34 inch inseam. Various sources that I have consulted have recommended anywhere from 175mm to 185mm!!! What do other tall riders do about crank arm length?


Anonymous's picture
"Chainwheel" (not verified)
Try 175mm

"People agonize over this way too much. A lot depends on your style (masher or spinner). Mashers generally prefer longer cranks. But within reason, I doubt you will notice much difference.

I'm 6'3"" with a 35.5"" inseam. I've got 175s on one bike and 172.5s on another (slightly lower gearing on the bike with 172.5).

185 sounds pretty extreme for someone with a 34' inseam. I think you'd be fine with 172.5 or 175.



Anonymous's picture
<a href="">Peter O'Reilly</a> (not verified)
that's alot of torso

Here's one data-point. I have the same inseam length and am 5.5 inches shorter than you. My main ride is with stock 172.5 cranks.

I never gave much thought to changing the length. I've ridden bikes with other crank lengths. You notice the change at 1st, then somewhat quickly forget about it as time passes. The body is a remarkable thing; it adapts very well to changes.

I think crank length as more of personal preference than a sizing/fit issue. I haven't broken out a ruler, but using 185mm crank lengths my guess is there should be concern with cornering clearance.

Anonymous's picture
JB (not verified)

I read about crank arm length recently in an article by Lennard Zinn. See:

Anonymous's picture
Evan Marks (not verified)
more Zinn crankiness

"Several years ago he published the results of his study of varying crank lengths from (I think) 175mm down to 130mm. As I recall*, one size stood out as inexplicably efficient (something strange,150mm perhaps) but he was unable to correlate it to anything or draw any conclusions other than generalities about our ability to adapt to a wide range of crank lengths.

Some people claim they can feel the difference between say, 170mm and 172.5mm (1/10""). Others switch back and forth between 170mm and 175mm and never notice any difference at all. ""So what?"" you ask. So use whatever you like - you'll probably adapt to it.

*No doubt, some NYCC crank still has the article and can prove my memory to be faulty."

Anonymous's picture
KJ (not verified)
Thanks Everybody!

I appreciate your help!

Anonymous's picture
Bill Vojtech (not verified)
one more opinion

Check out this article:

I've always thought it was strange that people go to great expense to get custom frames made to measure and fuss over a milimeter hear or there and then automatically slap a stock 170mm crank on it. Of course, it's hard to find non-standard length cranks, (above 175mm or below 165mm), but it can be done.

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