Crankarm Length Question
10-20-11, 11:08 AM
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Crankarm Length Question
I have a quick question on crankarm length. I know the general theory on femur length, etc. but am curious what your actual experience is. I'm 5' 7 1/4"
I ride a 52cm road bike frame with 170mm crankarms, and recently started riding a mtn bike with 175mm cranks, and they feel REALLY long and uncomfortable. I know typically they should be 2.5-5.0 more than the road cranks but I'm thinking of just going down to 170s anyway. Those 175s are killing me.
Anyone else around this height have an opinion?
I ride a 52cm road bike frame with 170mm crankarms, and recently started riding a mtn bike with 175mm cranks, and they feel REALLY long and uncomfortable. I know typically they should be 2.5-5.0 more than the road cranks but I'm thinking of just going down to 170s anyway. Those 175s are killing me.
Anyone else around this height have an opinion?
10-20-11, 11:13 AM
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This is mountain biking, precision isnt a real thing, just do what is comfortable for you, theory is only theory.
10-21-11, 07:45 AM
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Yeah, the biggest trick is to ride what feels right to you. I'm much taller than you and I ride a 175 on my road and commuter bikes, and a 180 on my mountain bikes. Mmm ... power.
10-21-11, 08:22 AM
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https://www.nashbar.com/bikes/Product...2_10000_202339
If you click on specs on that Nashbar cyclocross bike, you'll see different crank lengths for different frame sizes. As a matter of fact, I saw different stem lengths when looking at the Salsa Vaya website.
You could always use a book against your crotch against a wall to measure your inseam and go to https://www.bikefitting.com/ and click on frame size then frame size again and put in your inseam in mm. When you see your road size, you can look again at the cyclocross bike crank lengths that corresponds with the frame size recommended on bikefitting.com. Well, that's a shortcut, but maybe not totally scientific way of doing it.
If you click on specs on that Nashbar cyclocross bike, you'll see different crank lengths for different frame sizes. As a matter of fact, I saw different stem lengths when looking at the Salsa Vaya website.
You could always use a book against your crotch against a wall to measure your inseam and go to https://www.bikefitting.com/ and click on frame size then frame size again and put in your inseam in mm. When you see your road size, you can look again at the cyclocross bike crank lengths that corresponds with the frame size recommended on bikefitting.com. Well, that's a shortcut, but maybe not totally scientific way of doing it.
10-21-11, 08:36 AM
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Interesting...you reminded me about Zinn's calculator which does road and mtb, and it definitely suggests a 170 for me on mtn. The funny thing though is his calculators suggest a slightly larger road crank than mtn, which I thought was the opposite of common practice?
https://www.nashbar.com/bikes/Product...2_10000_202339
You could always use a book against your crotch against a wall to measure your inseam and go to https://www.bikefitting.com/ and click on frame size then frame size again and put in your inseam in mm. When you see your road size, you can look again at the cyclocross bike crank lengths that corresponds with the frame size recommended on bikefitting.com. Well, that's a shortcut, but maybe not totally scientific way of doing it.
You could always use a book against your crotch against a wall to measure your inseam and go to https://www.bikefitting.com/ and click on frame size then frame size again and put in your inseam in mm. When you see your road size, you can look again at the cyclocross bike crank lengths that corresponds with the frame size recommended on bikefitting.com. Well, that's a shortcut, but maybe not totally scientific way of doing it.
10-21-11, 11:51 AM
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Go with whatever length feels best for you. Personally, my bikes have crank lengths of 165, 170, and 175 mm and I hardly notice any difference between them - certainly not enough to consider changing any of them. But if 170mm feels better to you then go ahead and switch to that on the MTB.
10-21-11, 12:16 PM
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I definately feel a difference between 170s and 175s. I'm amazed you don't notice anything when switching a full 10mm, when most ppl say they can discern a substantial difference in changing just 2.5mm. But hey, more power to you for it to be a non-issue. One less thing to worry about! I wouldn't mind trying 165s sometime on my road bike, but will switch the mtn over to 170s as soon as I can.
10-21-11, 01:03 PM
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I can get up more hills with 175s but I couldn't stand the 170 road to 175 MTB difference either. I solved it by getting some 172.5 road cranks. That's a difference I can live with.
02-21-12, 06:14 PM
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Every one is different. I am only 5'6.5" and I exclusively use a 175mm crank, with zero problems. My inseam is only 29 inches and I still feel very comfortable on a 175mm crank, on both road and MTB. I like the thrust a 175mm crank makes, when mashing the pedals in high gear...but, that preference could also be from my BMX background - where super-long cranks rule the roost.
