The importance of crank length to the cyclist.

[CoachFergie]

That is part of the reason for this thread and the posting of the anecdotes - to get people to, at least, try shorter cranks.

Very amusing.

Another Frank Day spam thread making claims you can't back up.

 

[FrankDay]

Some more data folks. This is out of Italy, from someone who does a lot of bike fits for the pros. He simply didn't believe there could be much benefit to going shorter. So, he put himself on an excaliber ergometer (which has the capability of measuring crank torque r/l for the entire circle) and did 90 seconds at about the same wattage on 150 and 170 cranks. Here are the results First the 150 results:

Now the 170 results:

What a lot to learn from this. First, look at that right leg. The peak torque/power on the right is actually greater than on the left but the negatives on that leg are so great that the average power of the left leg is actually substantially greater. So much for the "just push harder" view. What happens on the back stroke is really important. And, a combined analysis like spinscan or SRM would tell you that the right leg was stronger. So much for the value of that tool.

Next compare the average minimums between 170 and 150, they decrease so much on the shorter cranks that the average power is actually increased even though the average maximums are slightly decreased. Apparently it is a lot easier to get the foot out of the way on the upstroke if one doesn't have to move it so far.

And, however this machine measures efficiency, it is substantially higher on the 150 cranks than the 170.

 

[FrankDay]

Some more data folks. This is out of Italy, from someone who does a lot of bike fits for the pros. He simply didn't believe there could be much benefit to going shorter. So, he put himself on an excaliber ergometer (which has the capability of measuring crank torque r/l for the entire circle) and did 90 seconds at about the same wattage on 150 and 170 cranks. Here are screenshots of the results First the 150 results:

Now the 170 results:

What a lot to learn from this. First, look at that right leg. The peak torque/power on the right is actually greater than on the left but the negatives on that leg are so great that the average power of the left leg is actually substantially greater. So much for the "just push harder" view. What happens on the back stroke is really important. And, a combined analysis like spinscan or SRM would tell you that the right leg was stronger. So much for the value of that tool.

Next compare the average minimums between 170 and 150, they decrease so much on the shorter cranks that the average power is actually increased even though the average maximums are slightly decreased. Apparently it is a lot easier to get the foot out of the way on the upstroke if one doesn't have to move it so far.

And, however this machine measures efficiency, it is substantially higher on the 150 cranks than the 170. Yes, I think we can say crank length matters.

 

[Tapeworm]

^ The assumptions are astounding. The inherent flaws of a anecdote pretending to be science laid bare right there.

 

[CoachFergie]

Dude has cranks to sell.

Tapeworm, are you at Tour of Tasmania? I am managing the FELT NZ Team there. TTT up Mt Wellington today, looked painful.

 

[Tapeworm]

Negative, my riders are out with injuries ATM. If only they had used shorter cranks and applied power through 360degrees, then they would be ahead of everyone and not caught in the crash.

Did it snow on Mt Wellington? I've had it snow on me in the middle of summer when up there. It was like being in NZ!

Oh and I just realised I typed "a anecdote", shoot me now.

 

[CoachFergie]

Yes it was rather warm down at the start with snow and fricking cold at the top. Yeah our team would have placed higher than 4th if we used 115mm cranks and trained on independent cranks. Pity we blew the budget on first generation power meters.

 

[FrankDay]

^ The assumptions are astounding. The inherent flaws of a anecdote pretending to be science laid bare right there.

??? Assumptions? "pretending to be science"? Could you be a little more specific? BTW, speaking of science, don't you find it interesting that the power difference seen here is very similar to that found in the Martin crank length study between 170 and 145?

 

[CoachFergie]

You mean not significant. Not surprising at all.

Any more anecdotes with pretty graphs to share

 

[Tapeworm]

??? Assumptions? "pretending to be science"? Could you be a little more specific? BTW, speaking of science, don't you find it interesting that the power difference seen here is very similar to that found in the Martin crank length study between 170 and 145?

Someone of your esteemed knowledge in physiology and physics shouldn't need it explained. One data set. One.

All I see is slightly lower power on a second effort. I also note the left-right variance is less on the longer cranks, therefore I conclude longer cranks help balance leg power.

 

[FrankDay]

Someone of your esteemed knowledge in physiology and physics shouldn't need it explained. One data set. One.

All I see is slightly lower power on a second effort. I also note the left-right variance is less on the longer cranks, therefore I conclude longer cranks help balance leg power.

LOL. Was it offered as anything that a single data set? And, you conclude that longer cranks help balance leg power? IMHO, that is a bizarre interpretation. Did you notice what was the main contributor to that balance problem, in that in both instances the right leg actually pushed harder but in both instances the overall power in the right leg was less than the left. And, the overall power was slightly greater with the shorter cranks. So, looking at this data your main conclusion is that there is an overall benefit to longer cranks? Is that correct?

One positive thing, at least you are here giving your opinion rather than ignoring and hoping the data just goes away.

 

[Tapeworm]

And, you conclude that longer cranks help balance leg power? IMHO, that is a bizarre interpretation.

How so? The percentages are better with the longer cranks. Seems like a logical conclusion. At least as logical as anything else concluded.

Did you notice what was the main contributor to that balance problem, in that in both instances the right leg actually pushed harder but in both instances the overall power in the right leg was less than the left. And, the overall power was slightly greater with the shorter cranks.

Yes I noticed. I noticed also that the short crank intervals seems to have been done first. I noticed that there is no mention of the potential variance in the measuring equipment (0.5, 1, 2 percent?). I noticed the time between intervals is not mentioned nor are the dimensions of the rider, cranks they normally use, whether they are trained or not (given the power was really, really low for a 90sec effort).

So, looking at this data your main conclusion is that there is an overall benefit to longer cranks? Is that correct?

No, my main observation is actually that the data is meaningless without anything to compare it to.

Now just repeat that data with 10 other cyclists with a control and you may have something worth commenting on.

 

[veganrob]

cadence

Please help me out.
Where it says "revolution", does that mean cadence? If so, why is the cadence higher for 150 cranks. If you are going to do a test and the wattage is the same shouldn't cadence be the same also?
Just curious.

 

[FrankDay]

How so? The percentages are better with the longer cranks. Seems like a logical conclusion. At least as logical as anything else concluded.

Huh? exactly what percentages do you see as being better with the longer cranks? By my reading the Excalibur gives an overall "efficiency" for the 170 cranks of 81.02% and for the 150 cranks of 85.97%. What percentages are you talking about as being better?

Yes I noticed. I noticed also that the short crank intervals seems to have been done first. I noticed that there is no mention of the potential variance in the measuring equipment (0.5, 1, 2 percent?). I noticed the time between intervals is not mentioned nor are the dimensions of the rider, cranks they normally use, whether they are trained or not (given the power was really, really low for a 90sec effort).

OK, valid points I guess. But, wouldn't it be better to be asking about those points rather than dismissing the result because you don't know the answer? The fellow who did this is quite experienced, doing bike fitting for some of the top european pros but I don't know the answers to your questions. I do know the person doing this was quite blown away by the results.

No, my main observation is actually that the data is meaningless without anything to compare it to.

Meaningless? Ugh, we have two tests that we can compare to each other. Isn't that something?

Now just repeat that data with 10 other cyclists with a control and you may have something worth commenting on.

I agree. But, shouldn't this data, especially when it seems to follow the Martin data pretty well, be enough to stimulate some researcher out there to go do what you suggest and to, perhaps, get you to thinking that you might have been missing something here? Instead, what you do is come here and demean it. I am completely blown away by your bias and negativity.

 

[FrankDay]

Please help me out.
Where it says "revolution", does that mean cadence? If so, why is the cadence higher for 150 cranks. If you are going to do a test and the wattage is the same shouldn't cadence be the same also?
Just curious.

This was a 90 second test. It is my understanding that "revolutions" is the number of pedal revolutions that were included in the analysis. And, I think it is normal that people typically compensate when going to a shorter crank but trying to maintain a similar effort by raising the cadence slightly. This helps keep pedal speed similar (although pedal speed is a little lower for the shorter cranks which probably accounts for the ability to better "get the foot out of the way" on the upstroke on the shorter cranks).

The purpose of the test wasn't to control anything other than to have similar output but to see what happens naturally when one shortens crank length significantly.

 

[Tapeworm]

Huh? exactly what percentages do you see as being better with the longer cranks? By my reading the Excalibur gives an overall "efficiency" for the 170 cranks of 81.02% and for the 150 cranks of 85.97%. What percentages are you talking about as being better?

Power distribution averages. With short cranks L - 52.35, R- 47.65. Long cranks L - 52.23, R 47.77. See, conclusive proof long cranks help balance power output...

OK, valid points I guess. But, wouldn't it be better to be asking about those points rather than dismissing the result because you don't know the answer? The fellow who did this is quite experienced, doing bike fitting for some of the top european pros but I don't know the answers to your questions. I do know the person doing this was quite blown away by the results.Meaningless? Ugh, we have two tests that we can compare to each other. Isn't that something?I agree. But, shouldn't this data, especially when it seems to follow the Martin data pretty well...

This is less than a 2% variance. The Excalibur, in this power range, has a variance of 2%. Martin showed up to a 4%, at most. IIRC. You could repeat the same test with the same cranks and easily get the same variances.

... enough to stimulate some researcher out there to go do what you suggest and to, perhaps, get you to thinking that you might have been missing something here? Instead, what you do is come here and demean it. I am completely blown away by your bias and negativity.

I am completely blown away by your assumptions and conclusion for highly inclusive data. I thought someone with your background would know how to interpret data. The bias is yours, not mine. I am open to seeing whether cranks length makes a difference. I have seen nothing to suggest this anything other than fluff. At best.

 

[FrankDay]

This is less than a 2% variance. The Excalibur, in this power range, has a variance of 2%. Martin showed up to a 4%, at most. IIRC. You could repeat the same test with the same cranks and easily get the same variances.

Yes, this is why this should be repeated in a real study. As Martin found, if power doesn't change between 170 and 150 (it would be nice if someone did this test in the aero position don't you think) then we can not worry about what crank length does to power and only worry about how it affects other things, like aerodynamics. That being said, this is a tiny part of what wowed me with this data. It was what happened to the power distribution in the front and the back with the change in crank length

I am completely blown away by your assumptions and conclusion for highly inclusive data. I thought someone with your background would know how to interpret data. The bias is yours, not mine. I am open to seeing whether cranks length makes a difference. I have seen nothing to suggest this anything other than fluff. At best.

So, you see nothing of potential importance in what happens to the negative forces on the upstroke as one changes crank length as having any significance even though the rider was able to maintain essentially the same power despite smaller torques on the downstroke (increasing overall pedaling efficiency) with the shorter cranks, is that correct?

If all you look or care about is total power then I agree, there is nothing in this data. I guess I like to look deeper.

 

[FrankDay]

anecdote pretending to be science

The above quote has been bothering me a bit and I thought I would comment on it again. One of the hallmarks of a good scientist is that they are good observers. Scientists try to explain what they observe but this first requires observing something new or different. It is the observing of new things and the subsequent attempts to explain the observations that leads to new discoveries. Careful observation is what led Darwin to propose the theory of evolution and natural selection. Making observations and hypothesizing about those observations, even if they seem unimportant to you, is just as "scientific" as the best experiment that examines those hypotheses. Whether such observations lead to anything important, well that is where those experiments are supposed to come in.

 

[Tapeworm]

...If all you look or care about is total power then I agree, there is nothing in this data...

Why would you, in the context of the graphs posted, care about anything else?

 

[Tapeworm]

The above quote has been bothering me a bit and I thought I would comment on it again. One of the hallmarks of a good scientist is that they are good observers. Scientists try to explain what they observe but this first requires observing something new or different. It is the observing of new things and the subsequent attempts to explain the observations that leads to new discoveries. Careful observation is what led Darwin to propose the theory of evolution and natural selection. Making observations and hypothesizing about those observations, even if they seem unimportant to you, is just as "scientific" as the best experiment that examines those hypotheses. Whether such observations lead to anything important, well that is where those experiments are supposed to come in.

That's awesome.

Do the research and start putting the evidence together to form your Theory of Cycling Pedalling Evolution. Darwin also had facts to help back up his theory and was very meticulous in collating it all together before actually fronting this idea to the general public. Be like Darwin, Frank. Sod off, get some real data which proves your point and then you can return and say "I told you so" in the smug air of one who has done a bucket load of work to justify what would normally be laughed at. Like it is now. Because the data you have is so less than nothing it just isn't worth talking about.

 

[FrankDay]

That's awesome.

Do the research and start putting the evidence together to form your Theory of Cycling Pedalling Evolution. Darwin also had facts to help back up his theory and was very meticulous in collating it all together before actually fronting this idea to the general public. Be like Darwin, Frank. Sod off, get some real data which proves your point and then you can return and say "I told you so" in the smug air of one who has done a bucket load of work to justify what would normally be laughed at. Like it is now. Because the data you have is so less than nothing it just isn't worth talking about.

Oh phooey. I am not putting forth a theory of evolution. I am making some observations about pedaling a bicycle that seems to get everyone's panties in a bunch. I throw my ideas out as a way of getting feedback in, hopefully, a collaborative sense. For instance, I would have never gotten this last crank length data if I hadn't been pushing people to try different crank lengths.

And, it would do me no good to get my own data because, as you know, as I would be seen as biased, even if my data was watertight. All I can do is try to get independent scientists to confirm or refute my thoughts by keeping this subject before them and the community. At least, it seems there is a good first effort to really examine this stuff underway soon being done by Gibson. Until then I continue to try to be a good observer and I tweak my hypotheses to try to explain those observations with the help of the rare insightful post I get on these forums. One thing being here and engaging in these back and forths has helped me to do is to be able to articulate my thoughts much more succinctly than I used to be able to do.

Anyhow, thanks for your participation.

 

[CoachFergie]

The above quote has been bothering me a bit and I thought I would comment on it again. One of the hallmarks of a good scientist is that they are good observers. Scientists try to explain what they observe but this first requires observing something new or different. It is the observing of new things and the subsequent attempts to explain the observations that leads to new discoveries. Careful observation is what led Darwin to propose the theory of evolution and natural selection. Making observations and hypothesizing about those observations, even if they seem unimportant to you, is just as "scientific" as the best experiment that examines those hypotheses. Whether such observations lead to anything important, well that is where those experiments are supposed to come in.

No, what you observed was not significant. ie not important. Not that it will stop you from claiming the win

 

[CoachFergie]

At least, it seems there is a good first effort to really examine this stuff underway soon being done by Gibson.

Judging by Mr Gibson's comments on Andy Coggan's facebook page he has already decided the outcome of his study. Not inspiring.

 

[FrankDay]

Judging by Mr Gibson's comments on Andy Coggan's facebook page he has already decided the outcome of his study. Not inspiring.

Everyone who designs a study must decide what the expected outcome might be, otherwise it is not really possible to design a proper study to test the hypothesis and the statistics. But then, it seems not much inspires you.

 

[CoachFergie]

But then, it seems not much inspires you.

Real performance gains inspire me. Not imaginary, made up or insignificant gains.

Also real feats of performance like Wiggins winning the Tour or Vos winning the Olympic Games Road Race.