The importance of crank length to the cyclist.

[Martin318is]

And, one other thing I would be interested in knowing is whether the apparent increased drag of the legs when on short cranks can be lowered any by increasing the distance between the legs.

Hadnt noticed that comment. Its an interesting question but I would add a word of caution. To avoid injury, Q factor should be based upon best tracking of the legs first before considering aerodynamics - if you can achieve both... Bonus!

 

[sciguy]

Originally Posted by sciguy:

"Actually he did initially test using a used set of adjustable Power Cranks that be purchased cheaply from Ebay. He locked them out so they acted as fixed cranks and tested lengths from 200mm to 165mm. His found the 175s to be the best compromise in terms of comfort and power and aeroness. So scratch that criticism of the list"


Frank Day:

Could you provide his raw data?

Sciguy's reply:

Frank,

Since he always trains with a power meter my friend spent literally dozens and dozens of hours perfecting his position on the bike as he was training. All of his training is testing and all testing is training. He has also optimized his IM distance nutritional regime during the course of his 3 to 5 hour trainer and outdoor rides. It's amazing how quickly you get into trouble digesting when your power output goes up just a bit too high . Since he isn't promoting a product, can not take a tax write off for the time and effort involved and perhaps chooses not to share with his competitors I assume he might decline. My guess is that you really didn't have to work nearly as hard to obtain Mike's data.


Sciguy said:

"I keep getting the feeling that you yourself have very little real personal experience riding time trial bikes or using power meters."

Hugh

Frank Day's reply:

What does that question, whether true or not, have to do with this data set?

Sciguy's reply:

Your lack of experience has vastly more to do with the initial experimental design than the data created by it. That said, GIGO comes to mind here.
Experience in riding time trials and using power meters would have prepared you to develop an experimental design which may well have provided much more effective use of the expensive wind tunnel time.

 

[FrankDay]

Hadnt noticed that comment. Its an interesting question but I would add a word of caution. To avoid injury, Q factor should be based upon best tracking of the legs first before considering aerodynamics - if you can achieve both... Bonus!

I am not aware of any evidence as to what constitutes "best tracking of the legs". My guess is there is a fairly wide range of "Q" that can be ridden efficiently if one trains with it. It also isn't clear to me that this change would make much of a difference but when it comes to complicated aerodynamics like this (where everything affects everything else) it is almost impossible to know what will happen without testing. I guess this might be amenable to a CFD analysis to give a sense of how wide the legs would have to be to begin to see a difference but that is way beyond my abilities.

 

[FrankDay]

Frank,

Could you tell us what Mike meant by "test best at 105"? Was it power and if so for what duration of test?

Thanks,

Hugh

Here is his original test data when he made that comment. These are 10 minute efforts.

Warm up for 15 min for each of the tests.

Cranks 145 Test #1
Max watts 669
Ave @ ½ way 399 for the full 10 min 353
Max speed 48.1 k
Ave @ ½ way 42.4 Full time 40.5
Max HR 181
Ave 173

Crank 125
Max watts @ ½ way 457 @ Full time 549
Ave @ ½ way 374 @ Full time 372
Max Sp 46.2
Ave @ ½ way 41.4 @ Full time 41.5
Max HR 180
Ave @ ½ 165 @ Full time 170

Crank 105
Max Watts @ ½ way 499 @ Full Time 558
Ave @ ½ way 392 @ Full Time 379
Max Sp 44.8
Ave @ ½ way 42k @ Full time 41.5
Max HR 183
Ave @1/2 way 169 @ Full time 174

He reported that the 125 test was after he broke a frame and he had trouble adapting to the new frame so he thinks those numbers could have been better and the 105 test was done with very little adaption time at that length so he feels those numbers might have been better with more adaption time.

He subsequently went back and retested at 145 similar to what he saw at 105 and his coach thinks he may have just been getting better at taking the test. He did not repeat the shorter cranks tests simply because they were costing him money and he felt he had found out enough.

 

[Martin318is]

I am not aware of any evidence as to what constitutes "best tracking of the legs". My guess is there is a fairly wide range of "Q" that can be ridden efficiently if one trains with it. It also isn't clear to me that this change would make much of a difference but when it comes to complicated aerodynamics like this (where everything affects everything else) it is almost impossible to know what will happen without testing. I guess this might be amenable to a CFD analysis to give a sense of how wide the legs would have to be to begin to see a difference but that is way beyond my abilities.

I am referring to issues such as ITB syndrome which can be triggered by things like poor knee tracking in the frontal plane. I did indicate in my comment that a range of positions are possible. Just highlighting that this must be given priority over aero

 

[TarmacExpert]

To avoid injury, Q factor should be based upon best tracking of the legs first before considering aerodynamics - if you can achieve both... Bonus!

http://webcache.googleusercontent.c...p?MyAbstractID=1179+&cd=2&hl=en&ct=clnk&gl=uk

 

[FrankDay]

http://webcache.googleusercontent.c...p?MyAbstractID=1179+&cd=2&hl=en&ct=clnk&gl=uk

Conclusions: The Q Factor that resulted in best TT performance differed between participants, suggesting that there is an optimum Q Factor for every cyclist. Deviation from optimal Q Factor cost the athlete 13.1w on average in the present study. It is therefore important to identify individual’s optimum Q Factor for maximum performance

Still not sure what constitutes optimal tracking though.

 

[sciguy]

BTW, it is my prediction that the aerodynamic benefits of short cranks will be even greater in headwind/windshear conditions, because more frontal area is being put in the wind shadow up high, where wind speed is greatest, and the head is lowered somewhat, where wind speed would be less.
.

Here is a bit of real world racing. The Youtube video linked below shows 30 seconds of the outbound leg at IMSA that took place last Sunday, April 22nd. Riders essentially rode directly into the wind for half of each 80k loop. The winds were a sustained 30knots for nearly all of the bike with peak gusts of 46 knots. The clip was recorded on a near perfectly flat section!!!!!

http://www.youtube.com/watch?v=Y91bHZDmrS0

I wouldn't want to be 1mm higher from the ground let alone several centimeters high on this day.

YMMV,

Hugh

 

[coapman]

Still not sure what constitutes optimal tracking though.

" The Martin study looked at the effect of crank length on one rep max power in cyclists "

What exactly is involved in this test ?

 

[simo1733]

Oh, I noticed that - and i assume others did too - but that is clearly a topic for a seperate thread
Chris Boardman has known about this since the 90s.Hence Kask have developed the Bambino helmet for Sky.

 

[acoggan]

http://webcache.googleusercontent.c...p?MyAbstractID=1179+&cd=2&hl=en&ct=clnk&gl=uk

Nice find.

Now, can you use your mad google skills to find the wind tunnel study of 'Q' and aerodynamic drag that was done in association w/ Project 96? (Hint: It was a masters thesis project by a member of the Air Force.)

 

[acoggan]

Experience in riding time trials and using power meters would have prepared you to develop an experimental design which may well have provided much more effective use of the expensive wind tunnel time.

+1. Or, Frank could have spent some of his obviously large amount of free time researching the subject in detail to see what has already been established, instead of wasting his client's money (I assume it was his client who was footing the bill, and Frank was just along for the ride) by starting completely from scratch. (Note that this is why, when asked for advice re. what wind tunnel is best for testing cyclists, I always tell people that the people with whom they would be working are really just as, if not more, important.)

 

[FrankDay]

Nice find.

Now, can you use your mad google skills to find the wind tunnel study of 'Q' and aerodynamic drag that was done in association w/ Project 96? (Hint: It was a masters thesis project by a member of the Air Force.)

My google must be broken. Perhaps you could actually provide a link to this work. Thanks.

 

[Martin318is]

Still not sure what constitutes optimal tracking though.

In loose terminology, a line that starts at a well balanced ankle joint, bisects the knee and continues through the hip. The term tracking refers to jinks of the knee, heel, or hip away from this line due to poor alignment. In my own case, poor alignment of my ankle caused by pronation in one foot was resulting in my hamstring pulling my knee inwards in part of the stroke and irritating my ITB. This was partly solved through orthotics and a change to a longer pedal spindle on one leg. (Thereby causing a change in Q factor on one side).

If I now start messing with my Q factor for aerodynamic reasons, I risk a repeat of the ITB issues I was experiencing due to the above. Therefore, my point - qfactor for correct position and tracking has precedence over aerodynamics - if however you can achieve both then well done.

 

[FrankDay]

In loose terminology, a line that starts at a well balanced ankle joint, bisects the knee and continues through the hip. The term tracking refers to jinks of the knee, heel, or hip away from this line due to poor alignment. In my own case, poor alignment of my ankle caused by pronation in one foot was resulting in my hamstring pulling my knee inwards in part of the stroke and irritating my ITB. This was partly solved through orthotics and a change to a longer pedal spindle on one leg. (Thereby causing a change in Q factor on one side).

If I now start messing with my Q factor for aerodynamic reasons, I risk a repeat of the ITB issues I was experiencing due to the above. Therefore, my point - qfactor for correct position and tracking has precedence over aerodynamics - if however you can achieve both then well done.

Well, I am glad to see you went with a wider q to fix your problem.

Anyhow, my experience suggests that most commonly the "tracking" problems you mention are mostly due to two problems. 1. poor muscle balance. 2. cranks that are two long. The muscle balance thing (and subsequent ITB problems) is generally and easily solved by training with PowerCranks. The cranks being too long thing is generally solved by … shorter cranks. I don't see q as being a big issue here. But, I guess if it were then the rider simply would not make the change. Sometimes we have to make trade-offs. It is possible this might be one but it is impossible to know unless we have the data, wouldn't you say?

 

[CoachFergie]

Well, I am glad to see you went with a wider q to fix your problem.

Anyhow, my experience suggests that most commonly the "tracking" problems you mention are mostly due to two problems. 1. poor muscle balance. 2. cranks that are two long. The muscle balance thing (and subsequent ITB problems) is generally and easily solved by training with PowerCranks. The cranks being too long thing is generally solved by … shorter cranks. I don't see q as being a big issue here. But, I guess if it were then the rider simply would not make the change. Sometimes we have to make trade-offs. It is possible this might be one but it is impossible to know unless we have the data, wouldn't you say?

Got a reference for that? My review of the literature would indicate that chronic cycling related lower limb injuries are caused by improper training progression, saddle too high or low and cadence too high or too low.

 

[Martin318is]

Well, I am glad to see you went with a wider q to fix your problem.

Why? You have absolutely no idea what my physiology is or what my position looked like pre or post the fitting. What was my starting position? How far did I move my foot out?

Its this kind of comment that I find ridiculous.

 

[Martin318is]

Anyhow, my experience suggests that most commonly the "tracking" problems you mention are mostly due to two problems. 1. poor muscle balance. 2. cranks that are two long. The muscle balance thing (and subsequent ITB problems) is generally and easily solved by training with PowerCranks. The cranks being too long thing is generally solved by … shorter cranks.

BS Frank.

Astonishing co-incidence that you manage to find that "in your experience" these problems are solved by your own product and a topic so dear to your heart. I just told you what the specific causes of my situation were and neither of your two problems were involved, neither indeed were either of your two solutions.

 

[Martin318is]

Got a reference for that? My review of the literature would indicate that chronic cycling related lower limb injuries are caused by improper training progression, saddle too high or low and cadence too high or too low.

Also, as per my comments to Frank - none of the above. No change has been made at all to my saddle position, crank length, or cadence,etc. It was all in the pronation of one foot and compensation in the other.

 

[FrankDay]

Also, as per my comments to Frank - none of the above. No change has been made at all to my saddle position, crank length, or cadence,etc. It was all in the pronation of one foot and compensation in the other.

A couple of points.

You have reported your experience. It may be that you have some sort of mechanical abnormality that could be corrected with simple orthotics and "Q" modification that was causing both your tracking and ITB problems.

But, you would be surprised as to how many reports I get back from customers that their chronic ITB problem disappeared in just a few weeks of training with PowerCranks, changing nothing else, as balance begins to appear in their leg muscles (fore/aft and right/left). Same with tracking, although crank length seems to independently fix this also.

So, you might be right but, in my opinion, it is more likely that your "fix" was more of a bandaid, simply masking symptoms, than a fix of the underlying problem that caused the issue. Of course, we will never know for sure.

 

[FrankDay]

BS Frank.

Astonishing co-incidence that you manage to find that "in your experience" these problems are solved by your own product and a topic so dear to your heart. I just told you what the specific causes of my situation were and neither of your two problems were involved, neither indeed were either of your two solutions.

The frequency that I hear these reports must be explained. Being a doctor, I have used some of my doctor knowledge to try to explain the reports I hear over and over. I guess it is an astonishing coincidence that I am both a doctor and have a product to sell (or, maybe the astonishing thing is that I actually listen to what my customers report to me so i can learn and expand my knowledge), but that by itself doesn't make my explanation BS. So, it is possible that your problem is different than what my experience says. But, you have no knowledge of what my experience is nor experience of having been trained as a physician to say my explanation is BS.

 

[FrankDay]

So much for the rational discussion we were having. Sorry about that folks. Hopefully, we can get back on track.

 

[CoachFergie]

So much for the rational discussion we were having. Sorry about that folks. Hopefully, we can get back on track.

That's what happens when one offers anecdotes as proof of ones position rather than actual evidence.

Martin, every person's pathologies are unique. My top three causes of lower body injuries in cyclists are based on a review of the cycling injury literature that appears to run counter to Frank's top two. Glad you found a solution. The solution to my lower body issues is a double hip replacement.

 

[Martin318is]

A couple of points.

You have reported your experience. It may be that you have some sort of mechanical abnormality that could be corrected with simple orthotics and "Q" modification that was causing both your tracking and ITB problems.

But, you would be surprised as to how many reports I get back from customers that their chronic ITB problem disappeared in just a few weeks of training with PowerCranks, changing nothing else, as balance begins to appear in their leg muscles (fore/aft and right/left). Same with tracking, although crank length seems to independently fix this also.

So, you might be right but, in my opinion, it is more likely that your "fix" was more of a bandaid, simply masking symptoms, than a fix of the underlying problem that caused the issue. Of course, we will never know for sure.

You may not know for sure - but myself and the expert fitter (also a sports physiologist) that made the assessment and determined the cause and solution do.

Bizare that you can sit there and claim that "take a power crank and call me in the morning" is somehow more appropriate than taking a 4 hour assessment of pedal action, posture, cadence, technique, flexibility, experience, etc. The person that did my fitting is able to point to before and after analysis to show what part of my pedalling action caused the irritation and that the changes that have been made have not only avoided that irritation but also allowed me to produce more power with less effort.

In my opinion, when you start talkig like this you sould like a chiropractor claiming that he can cure cancer.

 

[Martin318is]

That's what happens when one offers anecdotes as proof of ones position rather than actual evidence.

Martin, every person's pathologies are unique. My top three causes of lower body injuries in cyclists are based on a review of the cycling injury literature that appears to run counter to Frank's top two. Glad you found a solution. The solution to my lower body issues is a double hip replacement.

No problem! I am aware of that. I was merely highlighting for Frank's benefit that I am not saying these things because I am anti-frank or anti-powercranks. But I wanted to raise the point that there are other sources of these issues than he was implying and also that there are other solutions than buying as set of powercranks.