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The crank length thread

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The crank length thread

26 Feb 2013 03:42

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:

Oldman wrote: . . .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".
It is of great use to the sailor to know the length of his line, though he cannot with it fathom all the depths of the ocean. ~ John Locke
User avatar hiero2
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26 Feb 2013 17:57

hiero2 wrote: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.
Life is short, both reading my posts and training with PowerCranks will make it seem longer
FrankDay
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27 Feb 2013 13:19

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.
lostintime
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27 Feb 2013 14:37

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.
Hawkwood
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27 Feb 2013 15:10

lostintime wrote:… 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.
Life is short, both reading my posts and training with PowerCranks will make it seem longer
FrankDay
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27 Feb 2013 15:52

After following the threads on this subject I now understand why frivolous prank phone calls are frequently referred to as "crank calls".

:p
[SIZE="1"]
(Just a wee joke, there has been some good info.)[/SIZE]
"It's the biggest setback I've ever had in my cycling career*, so it's a new experience for me."
~ Lance Armstrong 2009 ~
*collar bone fracture
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27 Feb 2013 22:25

FrankDay wrote: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.
Oldman
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28 Feb 2013 00:05

Oldman wrote: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.
Life is short, both reading my posts and training with PowerCranks will make it seem longer
FrankDay
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28 Feb 2013 00:17

Cyivel
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28 Feb 2013 00:18

Cyivel
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28 Feb 2013 00:19

Cyivel
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28 Feb 2013 01:23

FrankDay wrote: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.



It's interesting that carpenters, with a huge range of arm lengths, seem to make do rather effectively with hammers that are pretty darn uniform in length for their given task. I wonder why that is? Perhaps the optimal hammer length is more a function of specific task rather than its owner's arm length.

YMMV,

Hugh
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28 Feb 2013 02:43

FrankDay wrote: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.


Call inseam links what you want. The "Anyhow" part is a prejudicial dismissal of a non-existent opinion.
I'm all for exploration of possibilities and have tried many different crank lengths, frame sizes, saddles, bars, positions and diets in different events. I have volunteered those experimentations and they are consistent with the hammer/lever example offerred earlier (an elegantly simple comparison that appears to be ignored). Physics are as physics does. So far I've seen diminishing returns at any crank length below 167.5 @ 5'8" in height. The same holds true for anything over 175 and I've ridden smaller and larger lengths. That's evidence to me.
Oldman
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28 Feb 2013 07:00

good restart. The tired tit for tat with those 2 was well tired...let that thread die die thread die


please no more "im a coach I need no proof but you arent therefore you must be wrong?" comment every 5 posts this time?
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28 Feb 2013 15:05

Boeing wrote:good restart. The tired tit for tat with those 2 was well tired...let that thread die die thread die


please no more "im a coach I need no proof but you arent therefore you must be wrong?" comment every 5 posts this time?


“Insanity is doing the same thing, over and over again, but expecting different results.”
It was all I could do to submit this comment I don’t know where the inspiration came from…
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28 Feb 2013 15:26

Y'all are cracking me up! Love it!

Sign me:
Hammerin' up that hill! Spinnin' a web on the roads!
It is of great use to the sailor to know the length of his line, though he cannot with it fathom all the depths of the ocean. ~ John Locke
User avatar hiero2
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28 Feb 2013 18:28

I dont give a crank, i ride whatever i want.
Testing the bounds of reality.
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08 Mar 2013 23:00

This is interesting as it shows the kind of adaption that can occur after 50 hours of PowerCranks training on short (150mm) cranks. This was sent to us by a customer today comparing a climb he did on his first PowerCranks outing and the "same" climb after 50 hours.
Image
One comment I had when I saw this was very few people would have been able to do that well on the first ride as he was able to complete that without stopping. I was told that he had listened to us and was riding 150mm crank length, which makes the PC's a lot easier. Both rides are on 150 crank length.

Notice his being able to sustain over 300 watts for 2 km on 150mm cranks. I will see if we can get him to repeat this after another couple of months.
Life is short, both reading my posts and training with PowerCranks will make it seem longer
FrankDay
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01 May 2013 00:15

Life is short, both reading my posts and training with PowerCranks will make it seem longer
FrankDay
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Posts: 3,194
Joined: 23 Sep 2010 16:30
Location: N. California

01 May 2013 00:40

Hmmmm, when you can't twist the science to suit your argument link someone's blog.

Outstanding.
Hamish Ferguson
coachfergblog.blogspot.co.nz
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