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  #16  
Old 11-02-2017, 12:48 AM
Kontact Kontact is offline
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I don't think there is any sort of unified theory of bicycle mechanics that actually dictates how long cranks should be. Everyone used 170s forever and tha was mostly fine. Crank length is not just the motion of your legs but part of the gearing.

I'm not surprised that arm length theories are all over the place. I'm short enough that some theories say that 170s are supposed to be "too long" for me, yet 30 years of riding on them doesn't seem to be a problem.
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Last edited by Kontact; 11-02-2017 at 12:02 PM.
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  #17  
Old 11-02-2017, 05:12 AM
marciero marciero is online now
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Some riders seem to be more sensitive than others in terms of knee pain or other issues. I have 170, 172.5, and 175 on different bikes that get a lot of use and am fine with either, though I can definitely feel the difference.
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  #18  
Old 11-02-2017, 07:03 PM
cribbit cribbit is offline
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Coming from a water polo background and being six and a half feet tall, I've found 175 to be my minimum crank size. About to move to 180's.

I've found that bad gear ratios (mashing rather than spinning) cause far more damage/pain than anything else.
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  #19  
Old 11-03-2017, 05:01 PM
kingpin75s kingpin75s is offline
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Quote:
Originally Posted by marciero View Post
Some riders seem to be more sensitive than others in terms of knee pain or other issues. I have 170, 172.5, and 175 on different bikes that get a lot of use and am fine with either, though I can definitely feel the difference.
^This.

I run mostly 170mm now but run some 175mm still. If I am climbing 4000ft or more on a dirt road ride, I am likely fine on the 170mm cranks, but my knees occasionally will give me trouble on the 175mm cranks. All this assumes reasonable Q (150 or less) as that is more important to me than crank length.

I am 5'10" with a short 30" trouser inseam for my height and have limited flexibility. Interested in this enough that I picked up a 160mm TA Zephyr double to test at some point on something with a low enough BB and that will be used for endurance and climbing.
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  #20  
Old 11-09-2017, 07:46 AM
nooneline nooneline is offline
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Originally Posted by Hombre View Post
Looking for personal experiences for long term use of shorter cranks?
I started at 172.5, then down to 170 at the start of the year.
I just bought some 165 cranks but have yet to receive them.

From what I've put together, there seems to be more to gain than to lose from going shorter.

Also, besides saddle height, what other adjustments are associated with short cranks? i.e. cleat position, saddle fore-aft, etc...

I've moved my cleats back when I went down to 170 and find it easier to maintain a higher cadence. Could also be psychological?

Thanks!
I just went from 170 to 165s on my road bike, and I love it. It was paired with a saddle change, so I should acknowledge that the changes I'm about to describe can't be isolated to the crank change.

First, I did raise my saddle 5mm to get the same leg extension at the bottom of the stroke. At the top of the pedal stroke this gives me a saddle height that's effectively 10mm higher for the top of the pedal stroke - a much more open hip angle. This gave me significantly greater comfort in a deep position - particularly in a TT-esque position. I think it's partly due to the saddle, accommodating better pelvic rotation, that this makes me want to put on a longer stem or longer handlebars.

The saddle I got, a Specialized Power, I definitely set it up a little bit further back than I expected. Part of this might be due to the specifics of this, as a short-nosed saddle, but part of it is likely due to the fact that the forward extension of my pedal stroke is now 5mm further back.

I do feel as though I lose a little bit of low-RPM push, but I gain comfort and smoothness everywhere else. Sprinting has improved, too, although that's part of ongoing sprint gains I'm making... but my first ride on the 165s and I did set a 12sec PR.
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  #21  
Old 11-09-2017, 02:29 PM
BdaGhisallo's Avatar
BdaGhisallo BdaGhisallo is online now
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Quote:
Originally Posted by nooneline View Post
I just went from 170 to 165s on my road bike, and I love it. It was paired with a saddle change, so I should acknowledge that the changes I'm about to describe can't be isolated to the crank change.

First, I did raise my saddle 5mm to get the same leg extension at the bottom of the stroke. At the top of the pedal stroke this gives me a saddle height that's effectively 10mm higher for the top of the pedal stroke - a much more open hip angle. This gave me significantly greater comfort in a deep position - particularly in a TT-esque position. I think it's partly due to the saddle, accommodating better pelvic rotation, that this makes me want to put on a longer stem or longer handlebars.

The saddle I got, a Specialized Power, I definitely set it up a little bit further back than I expected. Part of this might be due to the specifics of this, as a short-nosed saddle, but part of it is likely due to the fact that the forward extension of my pedal stroke is now 5mm further back.

I do feel as though I lose a little bit of low-RPM push, but I gain comfort and smoothness everywhere else. Sprinting has improved, too, although that's part of ongoing sprint gains I'm making... but my first ride on the 165s and I did set a 12sec PR.
I went to 165 cranks some years back for the same reason you cite - a more open hip angle at the top of the pedal stroke.
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  #22  
Old 11-09-2017, 05:25 PM
nooneline nooneline is offline
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Quote:
Originally Posted by BdaGhisallo View Post
I went to 165 cranks some years back for the same reason you cite - a more open hip angle at the top of the pedal stroke.
it's doubly important for shorties who like to get low.
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  #23  
Old 11-10-2017, 11:55 AM
sun sun is offline
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I'm 5'7 and I switched to 165mm a year ago. This has helped alleviate some knee pain after rides, but hasn't completely solved it. I'm just a bit more comfortable in lower positions and this has been the most noticeable.
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