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  #1  
Old 02-26-13, 03:42
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hiero2 hiero2 is offline
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Default The crank length thread

There was another thread about crankarm length - but it got hijacked so that it ONLY discussed extremely short crankarms and Powercranks. It earned this comment:

Quote:
Originally Posted by Oldman View Post
. . .I haven't checked this thread in about three months . . . assertion that shorter cranks help . . .
Same tired discussion...
So, I am starting this thread. This thread is for a general discussion of crankarm length. A few posts here and there mentioning extremely short cranks will be tolerated, but they should have their own thread. They are too controversial, and the discussion of short crank lengths blocked out everything else. So, continuing on about them here will be considered off-topic. Off-topic posts are covered in the forum rules.

For those readers who would like a mainstream viewpoint, and advice, on crank length, I think you could start with Lennard Zinn. I do not agree with Lennard on everything, but he is a smart man with lots of experience at what he does, and he is definitely a mainstream expert opinion.

technical-faq-with-lennard-zinn-when-it-come-to-crankarm-length-no-easy-answers

technical-qa-with-lennard-zinn-a-question-of-crank-length

technical-faq-with-lennard-zinn-feedback-on-crank-length-chaingate-ii

Lennard even answers a question about extremely short cranks in one of those linked posts.

As far as I can tell, extremely short cranks are still an oddity, and they are not considered mainstream theory. They share that distinction with right-angle cranks - at least 3 versions of which I have seen in my cycling career - 2 Italian designs, and one Tiawanese design. Although, the Tiawanese design used the "golden spiral" or the golden curve or some such to design a spiral crank - but it did the same thing as the Italian models. One Italian model made 3 right angle turns before it joined the spider - the other only one, in an "L" shape. But, I'm wandering - they aren't about crank length.

Anyway, for those who want to discuss extremely short cranks - you may start an "extremely short crank" thread, if one does not exist by that time - or you may visit the Powercrank thread, where such discussions may be allowed as being "on-topic".
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  #2  
Old 02-26-13, 17:57
FrankDay FrankDay is offline
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Quote:
Originally Posted by hiero2 View Post
There was another thread about crankarm length - but it got hijacked so that it ONLY discussed extremely short crankarms and Powercranks. It earned this comment:



So, I am starting this thread. This thread is for a general discussion of crankarm length. A few posts here and there mentioning extremely short cranks will be tolerated, but they should have their own thread. They are too controversial, and the discussion of short crank lengths blocked out everything else. So, continuing on about them here will be considered off-topic. Off-topic posts are covered in the forum rules.

For those readers who would like a mainstream viewpoint, and advice, on crank length, I think you could start with Lennard Zinn. I do not agree with Lennard on everything, but he is a smart man with lots of experience at what he does, and he is definitely a mainstream expert opinion.

technical-faq-with-lennard-zinn-when-it-come-to-crankarm-length-no-easy-answers

technical-qa-with-lennard-zinn-a-question-of-crank-length

technical-faq-with-lennard-zinn-feedback-on-crank-length-chaingate-ii

Lennard even answers a question about extremely short cranks in one of those linked posts.

As far as I can tell, extremely short cranks are still an oddity, and they are not considered mainstream theory. They share that distinction with right-angle cranks - at least 3 versions of which I have seen in my cycling career - 2 Italian designs, and one Tiawanese design. Although, the Tiawanese design used the "golden spiral" or the golden curve or some such to design a spiral crank - but it did the same thing as the Italian models. One Italian model made 3 right angle turns before it joined the spider - the other only one, in an "L" shape. But, I'm wandering - they aren't about crank length.

Anyway, for those who want to discuss extremely short cranks - you may start an "extremely short crank" thread, if one does not exist by that time - or you may visit the Powercrank thread, where such discussions may be allowed as being "on-topic".
One should ask the same question of everyone who purports to have a formula for proper crank length be it long or short, what is the basis for that formula or recommendation and is there any scientific support for it.

Another question one might ask when it comes to crank length is this: Riders range in size from 4'10" to 6'4", an approximate 30% range. Bike frames range in size from 48 to 62 cm, an approximate 30% range. The majority of crank lengths that come with bicycles range in length from 170 to 175mm, an approximate 3% range and the cranks in normal use range from 165 to 180, an almost 10% range. Why is such a narrow range of crank length seemingly appropriate for such a wide range of people?

Make your arguments for what you believe here.
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Old 02-27-13, 13:19
lostintime lostintime is offline
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Well .. gee.. With those paramters of discussion , it seems kind limited.
the differences between the common 170-180 is minimal at best. Yes, I've used them all . Now I ride Sugino XD 152's and they are "different" for sure !! Not a super short crank either , but short enough to really notice.

All these "theories" are just that. Nice and all ... but honestly , so what ? There is no "One" way to pedal a bike ... lol lol lol . Ride whatever you like and you'll be just fine.
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Old 02-27-13, 14:37
Hawkwood Hawkwood is offline
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Back in the 80s I ordered a new set of 175mm cranks, 180s turned up instead. I was about to send them back, then looked at 5mm on a ruler and thought it's nothing. I've used 180mm cranks ever since and love them. My very subjective view is that they're worth about one or two teeth on the freewheel when riding with others of a similar ability. I'm 187cm in height, and have an inseam of 93cms, so I'm pretty `leggy' for my height.

Last edited by Hawkwood; 02-27-13 at 15:37. Reason: missed a word out
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Old 02-27-13, 15:10
FrankDay FrankDay is offline
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Quote:
Originally Posted by lostintime View Post
… Ride whatever you like and you'll be just fine.
The only thing is that some of us think there can be quite a difference between "just fine" and "optimizing performance". Since crank length determines one of the three parameters where the rider interacts with the bike (where the pedals are, saddle, handlebar/aeropads) and where the pedals are pretty much dictates everything about a bike fit (since they are "fixed" and it is easy to move the saddle and handlebars around) it seems this topic is more important than most think and should be discussed and investigated much more than it is.
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Last edited by FrankDay; 02-27-13 at 19:37.
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  #6  
Old 02-27-13, 15:52
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FitSsikS FitSsikS is offline
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After following the threads on this subject I now understand why frivolous prank phone calls are frequently referred to as "crank calls".



(Just a wee joke, there has been some good info.)
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Last edited by FitSsikS; 02-27-13 at 15:53. Reason: typing
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  #7  
Old 02-27-13, 22:25
Oldman Oldman is offline
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Quote:
Originally Posted by FrankDay View Post
One should ask the same question of everyone who purports to have a formula for proper crank length be it long or short, what is the basis for that formula or recommendation and is there any scientific support for it.

Another question one might ask when it comes to crank length is this: Riders range in size from 4'10" to 6'4", an approximate 30% range. Bike frames range in size from 48 to 62 cm, an approximate 30% range. The majority of crank lengths that come with bicycles range in length from 170 to 175mm, an approximate 3% range and the cranks in normal use range from 165 to 180, an almost 10% range. Why is such a narrow range of crank length seemingly appropriate for such a wide range of people?

Make your arguments for what you believe here.
Handlebars generally range from 38 to 44cm @ 14% difference. Saddles vary in length; probably over the same range.
The length of bikes varies little for the same size wheel.
Sea leve is 0 while Mt Everest is 29,029' and growing....
Fun with statistics doesn't legitimize self-serving research as refutation of actual real world physics.
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Old 02-28-13, 00:05
FrankDay FrankDay is offline
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Quote:
Originally Posted by Oldman View Post
Handlebars generally range from 38 to 44cm @ 14% difference. Saddles vary in length; probably over the same range.
The length of bikes varies little for the same size wheel.
Sea leve is 0 while Mt Everest is 29,029' and growing....
Fun with statistics doesn't legitimize self-serving research as refutation of actual real world physics.
Inseams in cyclists vary from about 28" to 36" an approximate 30% difference. I am not so sure I would call these "statistics" so much but, rather, interesting body biometrics. Anyhow, if you believe that the way things are is good evidence as to the way things should be, so be it.
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  #9  
Old 02-28-13, 00:17
Cyivel Cyivel is offline
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http://www.youtube.com/watch?v=VC0jKaj2bes
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Old 02-28-13, 00:18
Cyivel Cyivel is offline
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http://www.youtube.com/watch?v=uEXsOqdzYhE
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