The crank length thread

[CoachFergie]

One person's opinion...

As I said, these are my personal experiences and I am sure there are lots of people that don't agree or have experienced other setups that work better for them. You have to find a balance between position, aerodynamics and power output and the determination of your optimum cranklength is for sure an important factor.

The evidence from peer review literature...

Power Output and Pedal Speed account for 98% of the varaibility in metabolic cost in this group of 9 cyclists. 99% of the variablity for each individual

Of the remaining 2% variability, crank length and pedaling rate each accounted for 1% or 0.02% of total

 

[FrankDay]

One person's opinion...



The evidence from peer review literature...

Originally Posted by Martin
Power Output and Pedal Speed account for 98% of the varaibility in metabolic cost in this group of 9 cyclists. 99% of the variablity for each individual

Of the remaining 2% variability, crank length and pedaling rate each accounted for 1% or 0.02% of total

Really Fergie, sometimes your posts seem to miss the whole point. Anyhow, as sciguy pointed out

You have to find a balance between position, aerodynamics and power output and the determination of your optimum cranklength is for sure an important factor.

Note that Martin's "peer reviewed" study doesn't address the issue of aerodynamics or comfort. Further, crank length directly affects pedal speed (unless the rider makes an exact compensation through an exact cadence change, not our experience) and in some power production. So, Martin's study says nothing about some of the issues being discussed and actually supports some of the other things being discussed.

 

[elapid]

Really Fergie, sometimes your posts seem to miss the whole point.

No, they actually hit the nail on the head. A peer-reviewed, published study ... crank length contributes 1% to power output. Aerodynamics and comfort are individual and not testable. This is a peer-review study and its results beats your anecdotes, Frank, particularly your cherry-picking anecdotes with your refusal to believe anecdotes which don't fit your cockamamie theories.

 

[FrankDay]

No, they actually hit the nail on the head. A peer-reviewed, published study ... crank length contributes 1% to power output. Aerodynamics and comfort are individual and not testable. This peer-review study and its results beats your anecdotes, Frank, particularly your cherry-picking anecdotes with your refusal to believe anecdotes which don't fit your cockamamie theories.

So, let me get this straight. You are saying crank length doesn't contribute to pedal speed? Is that correct?

And, you are saying aerodynamics is not testable? Is that correct?

 

[elapid]

So, let me get this straight. You are saying crank length doesn't contribute to pedal speed? Is that correct?

And, you are saying aerodynamics is not testable? Is that correct?

I am saying that Martin et al found that crank length contributes 1% to power output. Did I mention pedal speed? No. Regardless, power output is what matters, not pedal speed.

I am saying that testing aerodynamics on one individual rider is not applicable to another rider because of variabilities such as frontal area, flexibility, position, duration of ride and ability to maintain that position, and comfort.

 

[FrankDay]

I am saying that Martin et al found that crank length contributes 1% to power output. Did I mention pedal speed? No. Regardless, power output is what matters, not pedal speed.

I am saying that testing aerodynamics on one individual rider is not applicable to another rider because of variabilities such as frontal area, flexibility, position, duration of ride and ability to maintain that position, and comfort.

Martin found that crank length contributed about 1% to metabolic cost independent of pedal speed. However, he found pedal speed to be a major contributor to metabolic cost and crank length is a major contributor to pedal speed, isn't it? The devil is in the details. The hardest part of a study is not in gathering the data but in interpreting the data.

So, you are saying that it is not possible to test some general aerodynamic principles or relationships because of these individual variations? Is that what I am reading?

 

[CoachFergie]

I am saying that Martin et al found that crank length contributes 1% to power output. Did I mention pedal speed? No. Regardless, power output is what matters, not pedal speed.

I am saying that testing aerodynamics on one individual rider is not applicable to another rider because of variabilities such as frontal area, flexibility, position, duration of ride and ability to maintain that position, and comfort.

You can see why I no longer waste my time on trolls like Frank.

 

[elapid]

The hardest part of a study is not in gathering the data but in interpreting the data.

Martin et al have interpreted the data ... you've just misinterpreted the data. Should it be repeated again for you, Frank ... 1%. There is a reason no one is looking at crank length despite your protestations and the devil is not in the details in your case, because there is no detail other than crackpot theories.

 

[elapid]

You can see why I no longer waste my time on trolls like Frank.

+1. I should know better.

 

[FrankDay]

Martin et al have interpreted the data ... you've just misinterpreted the data. Should it be repeated again for you, Frank ... 1%. There is a reason no one is looking at crank length despite your protestations and the devil is not in the details in your case, because there is no detail other than crackpot theories.

Yes, Martin did interpret the data. However, sometimes it helps to have more than a rudimentary understanding of science and math to be able to understand their interpretation. I was going to put this in my last response but I held it out because I thought it was so obvious it would be demeaning and trying to be a good forum citizen I resisted but you now force me.

How does one know pedal speed. Well, one could measure it direcetly with something like a radar gun. If one doesn't have a radar gun available I wonder if one could calculate it from something they already measure.

Well, speed is nothing more than distance traveled per unit time, like how many meters per second or miles per hour. And, it turns out that pedals move in a circle so if we could only know the circumference of that circle and how many turns the pedal makes per second we could calculate pedal speed.

How many turns the pedal makes per second is easy as we can measure cadence, which is revolutions per minute and divide by 60 and we know revolutions per second.

But, how about that pesky circumference? Circumference of a circle is pi • D (diameter). The only thing we don't know here is the diameter. Wait, I got it. The D is 2 • r (radius) and the radius just happens to be the crank length.

I wonder how Martin got his pedal speed for his paper. I didn't see him mention a radar gun in his methods and materials so I assume he calculated it using crank length. He may not have mentioned this in his conclusions but unless you can tell me another way of doing this that doesn't involve crank length then crank length is part of the pedal speed discussion whether Martin mentioned it or not.

Sorry, but you and Fergie have the sophistication of high school sophomore literature majors when it comes to interpreting this stuff.

Further, just because a paper is peer reviewed does not mean it is correct. All it means is it met the base requirements of the journal for publication and the journal thought it would be of interest to its readers. Frequently authors make errors in interpretation and calculation that are picked up by the readers (just read the letters to the editor of any scientific publication). While it is interesting to read how the author interprets his data it is important that each reader draw his or her own conclusion based upon what is said (or not said) in relation to their own knowledge and experience. Accepting a single paper as true for what the author says is what lay people and journalists do.

 

[FrankDay]

Here is another anecdote somewhat related to crank length and the complete opposite of what I posted before. I suspect these two represent the range of possibilities.

A national level cyclist FTP tested to be 428 watts. This test was done in the road position. He reports his 10 mile TT power to be about 450 watts and his 25 mile TT power is usually in the 420's. By my eye is TT position is very good. Hence, his crank length (175, he is a big guy, 91kg) is having essentially zero effect on his ability to generate power in the TT position as his road position FTP and his 25 mile TT power are essentially the same nor do we see any problem in his ability to achieve a good position. Despite this he is still experimenting with crank length and not seeing much difference.

So, we have reports showing one rider seeing a huge difference in power (40 watts) in the TT position going to shorter cranks and another seeing almost no change in power in the TT position.

How does this help you? All it says, I think, is you can't know what is going to happen to you based upon the reports (or guesses) of others.

For most people under most circumstances it is my opinion that they probably should be riding the longest cranks they can that allow them to maximize both their torso's aerodynamic position and their sustainable power. That will vary a lot from person to person.

 

[elapid]

Accepting a single paper as true for what the author says is what lay people and journalists do.

Power output, Frank, that is what is important. Pedal speed means naught if you cannot generate the power while pedalling. Martin et al showed the relationship of crank length, pedal speed, and power output. It doesn't matter how he measured pedal speed. Meed I say it again ... 1% I would have expected you would have a better understanding than a primary school kid, but you don't. Now I know better.

 

[elapid]

How does this help you? All it says, I think, is you can't know what is going to happen to you based upon the reports (or guesses) of others..

It doesn't help at all. Stop with the anecdotes and provides us with real data ... peer-reviewed and published. If you cannot publish an alternative to Martin et al's research, then your criticisms of his paper mean absolutely nothing. You want to play in the scientific world, Frank, but you're just pretending.

 

[FrankDay]

Power output, Frank, that is what is important. Pedal speed means naught if you cannot generate the power while pedalling. Martin et al showed the relationship of crank length, pedal speed, and power output. It doesn't matter how he measured pedal speed. Meed I say it again ... 1% I would have expected you would have a better understanding than a primary school kid, but you don't. Now I know better.
…
It doesn't help at all. Stop with the anecdotes and provides us with real data ... peer-reviewed and published. If you cannot publish an alternative to Martin et al's research, then your criticisms of his paper mean absolutely nothing. You want to play in the scientific world, Frank, but you're just pretending.

Actually, I don't have to post an alternative to Martin's research. I can actually post and alternative that is also Martin's own peer reviewed research, just a different paper.

This is what Fergie recently posted regarding the Martin paper

Originally Posted by Martin
Power Output and Pedal Speed account for 98% of the varaibility in metabolic cost in this group of 9 cyclists. 99% of the variablity for each individual

Of the remaining 2% variability, crank length and pedaling rate each accounted for 1% or 0.02% of total

You two seemed to have missed the fact that in this paper Martin was not looking at power but, rather, the metabolic cost of cycling and how it might vary with certain variables. He concluded that 98% of the metabolic cost (how much oxygen you require) came from two variables, what power you were at and your pedal speed. Crank length, as an independent variable, was not very important regarding the metabolic cost of cycling.

But, in another paper Martin did look at the relationship of cycling power to crank length. Here is a chart from that paper that details his data.

There you go, real data, peer reviewed and published, showing power being greatest at a crank length of 145 compared to all other crank lengths tested.

I look forward to seeing your spin.

 

[Oldman]

Here is another anecdote somewhat related to crank length and the complete opposite of what I posted before. I suspect these two represent the range of possibilities.

A national level cyclist FTP tested to be 428 watts. This test was done in the road position. He reports his 10 mile TT power to be about 450 watts and his 25 mile TT power is usually in the 420's. By my eye is TT position is very good. Hence, his crank length (175, he is a big guy, 91kg) is having essentially zero effect on his ability to generate power in the TT position as his road position FTP and his 25 mile TT power are essentially the same nor do we see any problem in his ability to achieve a good position. Despite this he is still experimenting with crank length and not seeing much difference.

So, we have reports showing one rider seeing a huge difference in power (40 watts) in the TT position going to shorter cranks and another seeing almost no change in power in the TT position.

How does this help you? All it says, I think, is you can't know what is going to happen to you based upon the reports (or guesses) of others.

For most people under most circumstances it is my opinion that they probably should be riding the longest cranks they can that allow them to maximize both their torso's aerodynamic position and their sustainable power. That will vary a lot from person to person.

You reference the guy's weight and then attribute a reduction from his 175cm to shorter cranks as a basis for power increase? What's his weight got to do with it?
I had a 6' teammate that used 177.5 cranks and we eventually got him down to 175 for TT, 172.5 for road and he saw huge improvement. Improvement due to pedaling to position efficiency, not position.
Weight?

 

[elapid]

For you, Frank. Just in case you don't know, because I am uncertain of how much you truly understand, you are the pseudoscience.

 

[CoachFergie]

You reference the guy's weight and then attribute a reduction from his 175cm to shorter cranks as a basis for power increase? What's his weight got to do with it?
I had a 6' teammate that used 177.5 cranks and we eventually got him down to 175 for TT, 172.5 for road and he saw huge improvement. Improvement due to pedaling to position efficiency, not position.
Weight?

If I lost weight I would be able to maintain a lower position although, I guess a new Millenium problem, we now have overweight to obese kids racing track and those who rotate their pelvis forward are still able to accommodate their young fat guts and achieve a flat back position.

As mentioned I tilted my saddle up and was able to drop my handlebars 4cm.

But one off reports give us no confidence about application to others and we have little way of establishing what other factors influenced the outcomes. This is where the research is so important before we carry out time wasting experiments. Martin estimated the effect of different crank lengths on power delivery and found no meaningful differences between lengths until he went very short or very long. .5% maximum potential impairment for only the very tallest or very shortest of riders using a 170mm crank to a shorter or longer crank.

Then McDaniel doing the same for efficiency. And Thomas for Crank Length and Fatigue.

So the research has been done and the only one claiming it is wrong is the one who sells adjustable length cranks.

 

[elapid]

But, in another paper Martin did look at the relationship of cycling power to crank length. Here is a chart from that paper that details his data. There you go, real data, peer reviewed and published, showing power being greatest at a crank length of 145 compared to all other crank lengths tested.

What was the difference between 145mm and 170mm cranks? Definitely was NOT significant.

 

[CoachFergie]

For you, Frank. Just in case you don't know, because I am uncertain of how much you truly understand, you are the pseudoscience.

Excellent chart, sums these one off reports quite nicely.

 

[elapid]

So the research has been done and the only one claiming it is wrong is the one who sells adjustable length cranks.

+1. Frank is just trolling. This thread has been done to death and should be closed. The published evidence is conclusive, the fact that pros are not using anything other than standard crank lengths is conclusive (considering they're the ones who would junp on anything that gives them an advantage), and all we have against all this evidence is a car salesman pedalling his own cranks and providing meaningless anecdotes.

 

[CoachFergie]

+1. Frank is just trolling. This thread has been done to death and should be closed. The published evidence is conclusive, the fact that pros are not using anything other than standard crank lengths is conclusive (considering they're the ones who would junp on anything that gives them an advantage), and all we have against all this evidence is a car salesman pedalling his own cranks and providing meaningless anecdotes.

Well the crazy thing is that the original spam thread started by Frank, with links back to his commercial site, was closed and this thread was started by Hiero who is one of the mods.

In that time no one has offered any substantial data to counter the work of Martin and his group from the early last decade.

 

[FrankDay]

You reference the guy's weight and then attribute a reduction from his 175cm to shorter cranks as a basis for power increase? What's his weight got to do with it?
I had a 6' teammate that used 177.5 cranks and we eventually got him down to 175 for TT, 172.5 for road and he saw huge improvement. Improvement due to pedaling to position efficiency, not position.
Weight?

??? Weight, of course, would have nothing to do with any power increase. What I don't understand regarding your comment is the message you quote that mentions the persons weight stated the cyclist did not see a power increase. So, what did I miss?

Then, you give an anecdote about a person going to shorter cranks and seeing a big improvement but suggest the shorter cranks had nothing to do with this improvement because it was, instead, due to better "position efficiency", whatever that is. Could you clarify what "position efficiency" is or you meant to say?

 

[FrankDay]

What was the difference between 145mm and 170mm cranks? Definitely was NOT significant.

You do understand what "significant" means when put in a scientific paper. The generally accepted convention is it means the statistics show that the chance of the difference being due to chance is less than 1 in 20. In this case the statistics would probably show that the chance this difference is due to chance is probably about 1 in 10. So not "scientifically significant" as generally accepted but that doesn't mean the difference is not real. This study needs to be repeated with larger numbers to see if there really is or isn't a difference.

The toughest part of a scientific paper is not the data gathering but in the interpretation.

 

[FrankDay]

The published evidence is conclusive, the fact that pros are not using anything other than standard crank lengths is conclusive

LOL.

No single study is ever conclusive. In fact, it would be rare that even several studies would ever be conclusive.

The fact that the pros are not riding shorter cranks hardly means anything when their crank sponsors don't make shorter cranks. But, make your point if you think it persuasive.

 

[coapman]

Not sure if I mentioned it on CyclingForums but all I had to do to drop my handlebars 4cm without losing the beer gut was tilt my saddle up a little which allowed me to rotate the pelvis forward.

Where on the saddle is your bodyweight pressing down ? Wih the perfect