The pedaling technique thread

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Jul 4, 2009
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CoachFergie said:
Outstanding, a one off assessment of his own riding. Bias much?

Highlights why we wait for peer review scrutiny rather than a web page to make decisions where to invest our "performance enhancement" time and energy!
....actually, it was outstanding....most of Dr.Cheung's articles are usually most outstanding and the others simply outstanding....and yes, it was a one-off assessment of his own riding, but then it was not claimed to be anything else....and where do you get off criticizing Dr. Cheung on the basis of some alleged bias....for your information Dr. Cheung has probably has forgotten more about bias in research in the last day than you will ever know in a lifetime.....

....and what is this perverse fetish you have for the need for peer review scrutiny....I mean, when you get up in the morning do you immediately follow up on your decision to have your daily constitutional and go directly to the loo or do you wait for your decision to pass peer review scrutiny....

Cheers
 
Apr 21, 2009
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coapman said:
It's a pity this was not done by using the same power and only varying the gearing or cadence.
So you are saying that perhaps with more subjects, a range of powers and a range of cadences the analysis would have been better?

Way to earn that Boy Scout Science Merit Badge!!!
 
Sep 23, 2010
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42x16ss said:
All this shows is that the rider in question has an imbalance between left and right legs, whether this is something that can be fixed by shims, working with a physiotherapist or simply by specific gym work remains to be seen.

Not a deal breaking feature in a PM but could be useful in a few different circumstances (eg: post crash/injury/operation)
Really? That is all you got from this information? The rider is unbalanced? I guess I look at this stuff more closely than a lot of you.

Of course, without this information it wouldn't be possible to know that there is a real imbalance (this reviewer has been using a PM for many years and seemed unaware of this difference) and whether such manipulations (fixed by shims, working with a physiotherapist or simply by specific gym work) effectively fixed the issue. Ignorance is bliss. Knowledge is power.
 
Jul 4, 2009
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CoachFergie said:
So you are saying that perhaps with more subjects, a range of powers and a range of cadences the analysis would have been better?

Way to earn that Boy Scout Science Merit Badge!!!
.... did your childhood report cards always have the comment " does not play well with others" in them ?.....

Cheers
 
Jul 4, 2009
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FrankDay said:
Really? That is all you got from this information? The rider is unbalanced? I guess I look at this stuff more closely than a lot of you.

Of course, without this information it wouldn't be possible to know that there is a real imbalance (this reviewer has been using a PM for many years and seemed unaware of this difference) and whether such manipulations (fixed by shims, working with a physiotherapist or simply by specific gym work) effectively fixed the issue. Ignorance is bliss. Knowledge is power.
....I deduced the Unified Field Theory from that information....so do I get an extra special prize ? ....

....and please, take a deep breath and calm down, because you are verging on going all Coach Fergie on us ( and forum rules clearly stipulate that there can be only one Coach Fergie per thread...otherwise the threads go into nuclear meltdown mode and before you know it we'll all be in China...or worse, in Coach Fergie's living room...now we definitely don't want that do we ?... )....

Cheers
 
Sep 23, 2010
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sciguy said:
My prediction is that Frank will be surprised at how asymmetrically many of the folks who ride Powercranks actually pedal. We will soon find that "just getting them around the circle" does not ensure symmetric power application.

Hugh
Why would I be surprised? Little surprises me any more. My only surprise would be if PowerCrankers were just as asymmetric as those training on regular cranks, not that they are not perfectly balanced right/left. Training on PowerCranks should make people more balanced, not perfectly balanced. In fact, I am currently riding on a prototype pair of iCranks and finding small balance difference between my own right left legs.

I also notice that the balance I see on the meter keeps changing some. I believe this is probably due to a sampling error from the cadence not being in synch with the sample rate. So, one sample may show the right leg to include 60% pushing and 40% recovery and the left leg to be 40% pushing and 60% recovery. The number seen would show an imbalance when none existed. So, imbalance is better looked at for the average for a longer period than in a short snippet of time. Anyhow, to me there is a lot of potentially useful data here. Look how hard the rider is pushing down on the pedals at BDC. That force is doing essentially nothing to help drive the bike forward but is costing the rider lots of metabolic cost. If you think there is nothing to be gained analyzing such information so be it. I think there is lots to be gained from such analysis. Knowledge is power.
 
Sep 23, 2010
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blutto said:
....I deduced the Unified Field Theory from that information....so do I get an extra special prize ? ....

....and please, take a deep breath and calm down, because you are verging on going all Coach Fergie on us ( and forum rules clearly stipulate that there can be only one Coach Fergie per thread...otherwise the threads go into nuclear meltdown mode and before you know it we'll all be in China...or worse, in Coach Fergie's living room...now we definitely don't want that do we ?... )....

Cheers
Yes, extra credit for that. LOL.
 
May 13, 2011
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FrankDay said:
If you think there is nothing to be gained analyzing such information so be it. I think there is lots to be gained from such analysis. Knowledge is power.
Did I say there was nothing to be gained? I think they have great potential to show what's really going on with people's patterns of force application. I also believe it will prove positively that 40% power improvement is and always has been an outlandish claim for the use of certain products.

You're an interesting guy. First you rail against the use of power meters for the past 15 years calling them no more useful than a stop watch and or heart rate monitor and now suddenly cast others as Luddites when they don't instantly embrace the newest version of what they've been using for years.

YMMV,

Hugh
 
Sep 23, 2010
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sciguy said:
Did I say there was nothing to be gained? I think they have great potential to show what's really going on with people's patterns of force application. I also believe it will prove positively that 40% power improvement is and always has been an outlandish claim for the use of certain products.

You're an interesting guy. First you rail against the use of power meters for the past 15 years calling them no more useful than a stop watch and or heart rate monitor and now suddenly cast others as Luddites when they don't instantly embrace the newest version of what they've been using for years.

YMMV,

Hugh
Huh? I have "railed against" the use of PM's for all these years because when I have asked for any evidence that they provide any benefit to the athlete none has ever been provided. I think it is clear that just knowing your power does nothing to help the cyclist improve their power. The same work necessary to improve power can be done whether one has a power meter or not. If there is any evidence to the contrary I hope some of you might provide it. I have nothing against pm's per se other than I think they are a waste of money if one is getting them to improve their training or racing outcome. I understand why people think they should be beneficial. It is just there is zero evidence (other than the occasional anecdotal report) that they are.

My enthusiasm for this newer second generation of power meters is because I believe they are actually giving the rider information that will help them improve their power beyond what can be done without them because they will give them information regarding technique issues. And, I believe that this data will eventually inform the luddites out there that technique matters and that optimum power generation involves more than just pushing hard.

I believe technique matters and contrary to you, I believe this information will document why the 40% number is not only possible but why it happens. The luddites consistently refuse to believe that reports of improvement after use of the unnamed product could come from technique change and have to be explained by other things. Just look at the wasted forces in Cheungs stroke. Huge forces that are mostly not very tangential (his forces are only tangential at about 60º, when he has barely begun to start pushing hard). That is an awful lot of wasted energy if, in fact, it is possible to do it better. If he started his pushing sooner and stopped it sooner, with no other change, he would be much better off at zero metabolic cost. If Cheung were pushing down less and pulling back a little more at BDC he would see a big improvement in power at zero metabolic cost. Put a well trained PowerCranker on those cranks and compare their technique and see if there is a difference between him and Cheung? I believe it would be dramatic and obvious.

This article was a review of one person's experience and thoughts regarding the utility of these cranks. It only opens up the potential of the device. How useful this information is has yet to be determined. But, as we gather more and more information about technique and the results of those who have trained to change technique then we have a real basis for discussing pedaling technique.
 
Mar 12, 2009
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FrankDay said:
...The luddites consistently refuse to believe that reports of improvement after use of the unnamed product could come from technique change and have to be explained by other things...
By luddites do you mean the sports scientists who performed peer reviewed studies on decoupled cranks and found no change to power output?

Those luddites!
 
Apr 21, 2009
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Tapeworm said:
By luddites do you mean the sports scientists who performed peer reviewed studies on decoupled cranks and found no change to power output?

Those luddites!
Yup give me peer review over an anecdote any day.

Guess i am a luddite then!
 
Sep 23, 2010
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Tapeworm said:
By luddites do you mean the sports scientists who performed peer reviewed studies on decoupled cranks and found no change to power output?

Those luddites!
No. At least they were inquisitive enough to visit the question. It just turns out their studies were poorly designed and totally inadequate. By luddites I mean the luddites who actually think those studies proved anything about pedaling technique or about the ability to change pedaling technique or think the book is closed on this question.
 
Sep 23, 2010
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I have been looking at the Cheung data and believe we can take more from it than the narrative of the text. Let's analyze this screen shot, when the rider is at high power.

One thing the author noted was a discrepancy in power between the right and left leg (here it is 217/201, a 7% difference) and he concludes this is a strength issue that can be fixed with isolated leg training strengthening the weak leg. Yet, my read of this data suggests the problem is not a leg weakness but a "technique" difference between the legs. The issue isn't that the right leg is weaker but the direction of the forces are less tangential in the right leg, especially when the forces are large and on the backstroke.

The magnitude and direction of the applied forces are essentially equal and tangential from 335º to 75º on the clock (there is the anomaly at 360º on the left but the magnitude of the force keeps the applied forward force about the same there) and little improvement could be achieved here (other than to increase the size of the applied forces). (Actually, I could argue that improvements could be made in these forces to improve efficiency but this is very nuanced and, I believe, beyond this discussion.)

But, when we get to 90º things start to change. The left leg forces are only about 10º off of tangential whereas the right leg force is about 25º off of tangential. This means the left leg is getting about 98% torque efficiency whereas the right leg is only getting about 90% torque efficiency - 8% less power for the right leg for essentially the same pushing force. This difference is maintained from 90º to 150º while pushing forces are a maximum. They return to being about the same at BDC. But, then we come to the upstroke. The left leg maintains positive power on the upstroke to 240º (and never goes negative) while the right leg never sees positive power again until 330º and has substantial negatives.

I think it is clear the difference in power seen between the right and left leg here has nothing to do with the right leg being weaker, as most people think of the term, but is purely a technique issue. In my opinion the technique of the left leg here has little room for improvement. If the technique of the right leg were the same this rider would be at 434 watts, a pick up of almost 5% in wattage from technique alone. Most riders don't come close to seeing the technique demonstrated by the left leg so most people have dramatically more potential improvement in them from paying attention to this detail.
 
May 13, 2011
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FrankDay said:
Most riders don't come close to seeing the technique demonstrated by the left leg so most people have dramatically more potential improvement in them from paying attention to this detail.
and you know this based on?
 
Mar 10, 2009
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FrankDay said:
I have been looking at the Cheung data and believe we can take more from it than the narrative of the text. Let's analyze this screen shot, when the rider is at high power.

One thing the author noted was a discrepancy in power between the right and left leg (here it is 217/201, a 7% difference) and he concludes this is a strength issue that can be fixed with isolated leg training strengthening the weak leg. Yet, my read of this data suggests the problem is not a leg weakness but a "technique" difference between the legs. The issue isn't that the right leg is weaker but the direction of the forces are less tangential in the right leg, especially when the forces are large and on the backstroke.

The magnitude and direction of the applied forces are essentially equal and tangential from 335º to 75º on the clock (there is the anomaly at 360º on the left but the magnitude of the force keeps the applied forward force about the same there) and little improvement could be achieved here (other than to increase the size of the applied forces). (Actually, I could argue that improvements could be made in these forces to improve efficiency but this is very nuanced and, I believe, beyond this discussion.)

But, when we get to 90º things start to change. The left leg forces are only about 10º off of tangential whereas the right leg force is about 25º off of tangential. This means the left leg is getting about 98% torque efficiency whereas the right leg is only getting about 90% torque efficiency - 8% less power for the right leg for essentially the same pushing force. This difference is maintained from 90º to 150º while pushing forces are a maximum. They return to being about the same at BDC. But, then we come to the upstroke. The left leg maintains positive power on the upstroke to 240º (and never goes negative) while the right leg never sees positive power again until 330º and has substantial negatives.

I think it is clear the difference in power seen between the right and left leg here has nothing to do with the right leg being weaker, as most people think of the term, but is purely a technique issue. In my opinion the technique of the left leg here has little room for improvement. If the technique of the right leg were the same this rider would be at 434 watts, a pick up of almost 5% in wattage from technique alone. Most riders don't come close to seeing the technique demonstrated by the left leg so most people have dramatically more potential improvement in them from paying attention to this detail.


You are correct and I was wrong by reversing the situation in my explanation for reduction in negative torque, because the negative torque is occurring when the more effective leg is applying its max torque. I did notice that tangential difference today as I was checking length of applied forces for both legs and they appeared to be almost equal except for that at 4 o'c, but that could be balanced out by the weaker legs extra torque at 1 o'c. The increased negative torque in the less effective leg has also to be taken into account in all 4 examples. Could this change in tangential effect be caused by position on the saddle? But I still believe the less effective leg is a lazier leg as demonstrated by it having more negative torque. Changing the leading power leg as each leg completes 540 deg. not only gives on average equal power from both legs but also greater power output and an all important brief recovery period for each leg when sustainable high power output is required in time trials.
 
Mar 10, 2009
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FrankDay said:
My reading of the literature. Here is an example from google books

I dare you to find me a single study that has measured pedal forces in which the direction of the pedal forces compare favorably to those found in Cheungs left leg.

The important lines in that book page 140 are "Note, however, that only the knee joint appears to exhibit a significant moment at the top and early in the pedal cycle". This explains why all cyclists have that dead spot or weak sector in their pedalling and even the use of PC's cannot change that fact. When you have the knack of combining equal use of hip, knee and ankle around TDC, maximal torque can be applied there.
 
Sep 23, 2010
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coapman said:
The important lines in that book page 140 are "Note, however, that only the knee joint appears to exhibit a significant moment at the top and early in the pedal cycle". This explains why all cyclists have that dead spot or weak sector in their pedalling and even the use of PC's cannot change that fact. When you have the knack of combining equal use of hip, knee and ankle around TDC, maximal torque can be applied there.
I would be interested in hearing your explanation as to how the hip and the ankle can do any substantial work at TDC, let alone be used "equally" to the quads (knee).

I would say that your thoughts of maximizing force across the top (as a way of maximizing power) are, pretty much, right on but your analysis of what is going on and how to achieve it are bizarre. If Cheung increased his forces across the top more (to be the equal of the posterior forces at BDC) I think his left leg pedaling technique would closely resemble what you call your linear technique and what I call "pedaling in circles". If I am wrong in that assessment I look forward to your showing us how you predict the "linear" style would look on these cranks. Should be easy enough.
 
Mar 10, 2009
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FrankDay said:
I would be interested in hearing your explanation as to how the hip and the ankle can do any substantial work at TDC, let alone be used "equally" to the quads (knee).

I would say that your thoughts of maximizing force across the top (as a way of maximizing power) are, pretty much, right on but your analysis of what is going on and how to achieve it are bizarre. If Cheung increased his forces across the top more (to be the equal of the posterior forces at BDC) I think his left leg pedaling technique would closely resemble what you call your linear technique and what I call "pedaling in circles". If I am wrong in that assessment I look forward to your showing us how you predict the "linear" style would look on these cranks. Should be easy enough.

At TDC and BDC Cheung's isolated knee torque is limited to that of a person rolling his foot over a barrel and scraping dirt from his shoe and extra training will not improve that fact. I have already explained many times how maximal torque is generated through 12 , 1 and 2 o'c, with the correct bike set up and position muscles are used in exactly the same way as indoor tug o'war men use their muscles. All that's involved is the combination of upper and lower body muscles with the upper body in a low ideal aerodynamic position. I pedal in semi circles, all concentration is on 180 degrees of continuous torque from each leg. I am telling you what the torque is at 12, 1 and 2 o'c, it is maximal (equal force and equal tangential effect), what is there to predict.
 
Sep 23, 2010
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coapman said:
At TDC and BDC Cheung's isolated knee torque is limited to that of a person rolling his foot over a barrel and scraping dirt from his shoe and extra training will not improve that fact. I have already explained many times how maximal torque is generated through 12 , 1 and 2 o'c, with the correct bike set up and position muscles are used in exactly the same way as indoor tug o'war men use their muscles. All that's involved is the combination of upper and lower body muscles with the upper body in a low ideal aerodynamic position. I pedal in semi circles, all concentration is on 180 degrees of continuous torque from each leg. I am telling you what the torque is at 12, 1 and 2 o'c, it is maximal (equal force and equal tangential effect), what is there to predict.
If you say so.

And, I could use a picture. Helps me to understand. And, I would really like to know what you think you are doing around the entire circle as that is what these cranks are going to show you should you ever dare to get on a pair.
 
Sep 14, 2012
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Pedaling Efficiency

Wow.

Heated discussion.

From my experience fitting and coaching pedaling technique >400 riders annually, these are my findings:

1. Pedaling Efficiency Can be Improved (Including the "Dead-Spot") Through Technique Training and Biofeedback.

2. Bike Fit impacts leg function and Force Vectors.

3. Measuring independent leg function with a "fixed" crank design provides very different (and in my opinion less-accurate) data than when measured using an "independent" crank design. This is due to the contralateral leg bias inherent to fixed crank-arms.

4. Much of the data used to describe counterproductive pedaling neglects to account for kinetic and mechanical forces, and doing so has a profound impact (for the better) on force vectors.

At the end of the day, I'm less concerned about bieng right than providing good service and MEASUREABLE power improvements for my clients.


ccb
 
Sep 23, 2010
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bicyclefitguru said:
4. Much of the data used to describe counterproductive pedaling neglects to account for kinetic and mechanical forces, and doing so has a profound impact (for the better) on force vectors.
Thanks for joining in. Can you expand on this thought? It isn't clear to me what you mean.
 
Mar 10, 2009
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FrankDay said:
If you say so.

And, I could use a picture. Helps me to understand. And, I would really like to know what you think you are doing around the entire circle as that is what these cranks are going to show you should you ever dare to get on a pair.

Maybe it's time for you to explain how you believe PC's can get a possible total 40% extra torque from the almost powerless knee joint as it passes through TDC and BDC. What would an EMG test on a seasoned PC rider show at these sectors. As for my TT semi circular style which can be switched on or off at any time, max force application takes place from 11 to 5 where unweighting and and drawing back of foot occurs until about 10 o'c where leg prepares for max force application at 11. Unlike the mashing and circular styles, the thigh is going down as pedal passes through 12 o'c instead of rising, giving greater clearance than other styles for an aerodynamic position.
 
Sep 23, 2010
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coapman said:
Maybe it's time for you to explain how you believe PC's can get a possible total 40% extra torque from the almost powerless knee joint as it passes through TDC and BDC. What would an EMG test on a seasoned PC rider show at these sectors. As for my TT semi circular style which can be switched on or off at any time, max force application takes place from 11 to 5 where unweighting and and drawing back of foot occurs until about 10 o'c where leg prepares for max force application at 11. Unlike the mashing and circular styles, the thigh is going down as pedal passes through 12 o'c instead of rising, giving greater clearance than other styles for an aerodynamic position.
Explaining a 40% increase is easy when one considers the entire circle. Relatively small increases, when integrated around the entire pedaling circle, can quickly add up to large overall increases. It doesn't occur at the top, the bottom, or the back, or the down, It occurs everywhere.

Now that has been said, I am really really interested in knowing how it is the thigh is going down at TDC when using your style and not when using other styles.
Unlike the mashing and circular styles, the thigh is going down as pedal passes through 12 o'c instead of rising, giving greater clearance than other styles for an aerodynamic position.
 
Mar 10, 2009
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FrankDay said:
Explaining a 40% increase is easy when one considers the entire circle. Relatively small increases, when integrated around the entire pedaling circle, can quickly add up to large overall increases. It doesn't occur at the top, the bottom, or the back, or the down, It occurs everywhere.

Now that has been said, I am really really interested in knowing how it is the thigh is going down at TDC when using your style and not when using other styles.
Give a breakdown of that 40% at each of these sectors TDC downstroke BDC and upstroke. What is being trained by PC use at TDC and for downstroke
 

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