The pedaling technique thread

[FrankDay]

Regarding energy efficiency from glucose, and ATP -
I found this info in a college chemistry textbook -

Fundamentals of Chemistry
General, Organic, and Biological
H.Stepehn Stoker
Edward B. Walker
2nd edition, 1991

Chapter 27, Mitochondrial Oxidation and Phosphorylation Pathway,
page 702

"
Let us briefly consider the efficiency of total glucose oxidation from glucolysis through oxidative phosphorylation. If we seledt liver tissue, where the malate shuttle predominates, we gain 38 moles of ATP from the oxidation of 1 mole of glucose. With 7.3 kcal/mole of free energy stored in each ATP bond, this represents a total of 38 ATP X -7.3 kcal/mole (-277.4 kcal) of free energy captured for use. If we recall that the 'delta G' for the direct combustion of glucose to CO2 is -686 kcal/mole, we can calculate the efficiency in capturing this fee energy.
energy stored in 38 ATP high-enery bonds -> -277 kcal
free energy from combustion of glucose -> -686 kcal
= 40%
"

Is this helpful, or relevant?

Jay Kosta
Endwell NY USA

Not really as we are "discussing" the best potential external work done by muscles (energy out) vs the energy cost. Whatever that number is it isn't germaine to the issue of what are the potential losses involved in trying to transfer that muscle work to the bicycle, which is what I am focused on. This muscle efficiency thing is simply a diversion by some to avoid discussing that question.

 

[acoggan]

Now if we could get you to address the efficiency loss between that high efficiency "electric motor" and the efficiency measured at the pedals (around 20%), definitely not in the "high efficiency electric motor" class. And, how do we explain the huge gross efficiency range seen in cyclists (16-26%)? If we don't understand those losses then we really don't understand much about cycling physiology/mechanics, do we?, as those are the largest losses seen in cycling power production chain after the muscle. yet it has been ignored by the research community as near as I can tell.

You seem to have missed my point. Once you take int consideration 1) essentially obligatory energy "losses" in the production of ATP, and 2) the economy/efficiency of the legs (vs. the body as a whole), cyclists are amazingly efficient.

 

[acoggan]

For those who are proposing a maximum muscle contraction efficiency of 27% resulting in cyclist overall efficiency of up to 26% I am wondering how you account for chain losses of 2-7%? I think many accept 5% loss as being typical good estimate of chain loss at average power (150-200 watts) for the condition most chains are in.

Further, I take it you are not advocates of "the aggregation of marginal gains" advocated by British Cycling and Team Sky mentioned in the link above, not that they are any good.

When we add wheel bearing losses of about 1% and rolling resistance losses of 10% or more (although rolling resistance losses are probably not part of many cycling efficiency calculations unless the output is measured on an ergometer like the Computrainer) See this model published by Martin et al

You're confuse, Frank: cycling efficiency is measured "upstream" of the mechanical losses you mention.

 

[JamesCun]

Not really as we are "discussing" the best potential external work done by muscles (energy out) vs the energy cost. Whatever that number is it isn't germaine to the issue of what are the potential losses involved in trying to transfer that muscle work to the bicycle, which is what I am focused on. This muscle efficiency thing is simply a diversion by some to avoid discussing that question.

Your arguments are pathetic and so transparent. You started this entire discussion by claiming the 40% number for muscle contraction and 20/26% cycling efficiency. You obviously thought that was Relevant to your initial point. Now you've shofted the goal post and it all of a sudden isn't relevant.

You've created a scenario that most here don't agree with, then asked a question to validate your claims related to that scenario, then badgered people to disprove your claims. If people don't agree with your initial scenario, it becomes irrelevant to disprove the claims based on that scenario.

You love to make huge claims and then badger people who disagree. If you weren't so compelled to make the the bold claims, people might be more inclined to leave you alone. If you had simply suggested that people discuss the possible causes of reduced cycling economy, you might elicit some useful replies. But, you choose to bait people in your typical arrogant and aggressive fashion, so people are more inclined to poke holes in everything you say. You reap what you sow.

 

[FrankDay]

Your arguments are pathetic and so transparent. You started this entire discussion by claiming the 40% number for muscle contraction and 20/26% cycling efficiency. You obviously thought that was Relevant to your initial point. Now you've shofted the goal post and it all of a sudden isn't relevant.

Ugh, this portion of the discussion started back on posts 705 and 706. In 706 I choose some generally accepted numbers (amongst those familiar with this work) regarding muscle efficiency and cycling efficiency to illustrate why I thought their were some substantial losses associated with the pedaling stroke that suggested the average cyclist was pretty "awful" in this regard to answer the question in post 705. As the discussion has progressed I have stated that the exact number of the muscle efficiency number isn't important (other than it has to be larger than the overall cycling efficiency so as to not violate any laws of thermodynamics) because there still have to be losses between the muscle and the pedal as demanded by the laws of thermodynamics. As you and SciGuy would seem to argue it doesn't matter how the rider pedals, the energy transfer will have the exact same energy loss - zero.

You've created a scenario that most here don't agree with, then asked a question to validate your claims related to that scenario, then badgered people to disprove your claims. If people don't agree with your initial scenario, it becomes irrelevant to disprove the claims based on that scenario.

If you call pointing out that someones claim violates the laws of thermodynamics "badgering" them then so be it. I am simply trying to discuss the losses that occur between the muscle and the pedal.

You love to make huge claims and then badger people who disagree. If you weren't so compelled to make the the bold claims, people might be more inclined to leave you alone. If you had simply suggested that people discuss the possible causes of reduced cycling economy, you might elicit some useful replies. But, you choose to bait people in your typical arrogant and aggressive fashion, so people are more inclined to poke holes in everything you say. You reap what you sow.

If you say so.

 

[FrankDay]

You're confuse, Frank: cycling efficiency is measured "upstream" of the mechanical losses you mention.

Doesn't it depend upon the equipment upon which it is measured as to what losses are included and what are not? Not including the chain and bearing losses makes the losses between the muscles and the pedals even larger than I have proposed wouldn't it? Wouldn't this make any recoverable losses even greater making the need to investigate this even more important to the serious cyclist?

 

[JamesCun]

Ugh, this portion of the discussion started back on posts 705 and 706. In 706 I choose some generally accepted numbers (amongst those familiar with this work) regarding muscle efficiency and cycling efficiency to illustrate why I thought their were some substantial losses associated with the pedaling stroke that suggested the average cyclist was pretty "awful" in this regard to answer the question in post 705. As the discussion has progressed I have stated that the exact number of the muscle efficiency number isn't important (other than it has to be larger than the overall cycling efficiency so as to not violate any laws of thermodynamics) because there still have to be losses between the muscle and the pedal as demanded by the laws of thermodynamics. As you and SciGuy would seem to argue it doesn't matter how the rider pedals, the energy transfer will have the exact same energy loss - zero.

Ugh...what an arrogant and condescending pile of crap to say 'ugh' like everyone else is too dense to understand these simple concepts and you are so inconvenienced to be forced to respond.

You made the first claims in post 704, to which Sciguy responded and you then expanded on your initial claims. Don't try to change facts.

Don't try to pull this BS line of thermodynamics. That's just the pretty girl to distract from the magician.

 

[FrankDay]

You seem to have missed my point. Once you take int consideration 1) essentially obligatory energy "losses" in the production of ATP, and 2) the economy/efficiency of the legs (vs. the body as a whole), cyclists are amazingly efficient.

I disagree. Cyclists are not amazingly efficient. According to a paper I linked to earlier, about half the efficiency of the runner. 20% is really not very efficient, about the efficiency of the average internal combustion engine. This compares to the efficiency of a steam turbine to produce electricity of about 50%. When this is combined with a high efficiency electrical motor of about 90% the overall efficiency of an electric motor is 40-45% (there are some generation and transmission losses also). The bicycle is efficient mode of transportation per watt. The engine of the bicycle is not very efficient as engines go with an overall efficiency of 20%.

Anyhow, the purpose of this current discussion is to discuss "the economy/efficiency of the legs" in transferring the output of the muscles to the pedals. Since I presume you agree with me that efficiency is not 100% why don't you tell us where you believe the losses occur and how large they are to get us to that overall 20% cycling efficiency.

 

[FrankDay]

Don't try to pull this BS line of thermodynamics. That's just the pretty girl to distract from the magician.

So according to you the laws of thermodynamics are not laws but only suggestions. If you say so.

 

[acoggan]

Frank has a scary lack of knowledge on a subject that is central to his entire 15year crusade agains mashers. Hard to believe that he hadn't learned anything about cycling economy over all that time.

Those that have met him in person have formed a different (although no more flattering) impression of why he says/writes the things he does.

 

[coapman]

So according to you the laws of thermodynamics are not laws but only suggestions. If you say so.

Do you believe or claim that PC's can improve pedalling muscle efficiency ? Muscle efficiency is not the problem in cycling, cyclists don't know how to use them for best results. The ideal pedal stroke should be able to apply continuous peak torque over 180 deg. but that's impossible. The percentage figure worth considering then is how much of that torque can a rider apply in each 180 deg. stroke, this will give the true efficiency of your pedalling.

 

[sciguy]

There is a lot of nuance to what is a theoretical optimal muscle usage. Most cyclists are just awful in this regards.

I'm still waiting for you to provide a scintilla of evidence that this is the case.

In regards to whether or not most cyclists are awful in their technique we did hear from Jim Martin who actually has done a good deal of testing.

Note that muscular power is always positive and this is typical of most cyclists we see in our lab. Very few actually produce negative (counterproductive) power with muscular actions even when highly fatigued. So, muscular power during leg flexion is, in fact, positive throughout the cycle. Its just not usually high enough to overcome the non muscular demand. As I mentioned above, the other leg is extending during this phase so the net non muscular power from both pedals is nearer to zero throughout the cycle and averages to zero for a complete revolution during steady state cycling.

I would certainly agree that one's technique was awful if they were actively working against themselves but as Jim has seen, this is very uncommon.

Hugh

 

[JayKosta]

...
If you had simply suggested that people discuss the possible causes of reduced cycling economy, you might elicit some useful replies.
...

--------------------------------------------
Yes! your suggestion is a useful way discuss 'pedaling technique'.

I think that any purely 'radial force' applied to the pedal by active muscle contraction has low effectiveness.
E.g. any intentional pulling-up or pushing-down at TDC or BDC, forward or rearward muscle contraction at 3 or 9 o'clock has very low usefulness - its only value might be to initiate effective contraction for the 'next segment' of pedal motion.

I realize that there will be some amount of 'residual' radial force on the pedal at these positions due to gravity and momentum, but direct radial force due to muscle contraction is of questionable value.

Jay Kosta
Endwell NY USA

 

[FrankDay]

I'm still waiting for you to provide a scintilla of evidence that this is the case.

I did provide you the evidence that led me to that conclusion. Since that wasn't adequate, let alone even a scintilla of evidence for you I will provide something else that you posted back in post 750

James,

Another really interesting study was carried out by Moseley, Acten, Martin and Jeukendrup back in 2004 where they found:
No differences in cycling efficiency between world-class and recreational cyclists.
http://www.ncbi.nlm.nih.gov/pubmed/15241718

The high level pros were no more efficient than everyday joe cyclists with very little experience and much lower levels of fitness. Quite a surprising result as one would expect better economy from those with many years of experience as well as success in racing. I'd love to see the GE and DE from a number of long term Powercranks and see how they stack up. If Frank's assertions are correct they all should have very high values since their techniques have been so well trained

Hugh

Could you name a single other sport in which the beginners and experts have essentially the same skill and technique for the most important thing they do? Just the fact that both the beginners and experts have essentially the same pedaling technique strongly suggests all of them have lots of room for improvement. The problem seems to be that cyclists (at least some of them) don't have a clue what they need to do or how to achieve it. Isn't that what the pedaling technique thread is supposed to be discussing?

In regards to whether or not most cyclists are awful in their technique we did hear from Jim Martin who actually has done a good deal of testing.



I would certainly agree that one's technique was awful if they were actively working against themselves but as Jim has seen, this is very uncommon.

Hugh

So, you don't believe the forward forces seen when the pedal is moving backwards shown below, representative of a typical cyclist, represents "working against themselves"?

 

[FrankDay]

--------------------------------------------
Yes! your suggestion is a useful way discuss 'pedaling technique'.

I think that any purely 'radial force' applied to the pedal by active muscle contraction has low effectiveness.
E.g. any intentional pulling-up or pushing-down at TDC or BDC, forward or rearward muscle contraction at 3 or 9 o'clock has very low usefulness - its only value might be to initiate effective contraction for the 'next segment' of pedal motion.

I realize that there will be some amount of 'residual' radial force on the pedal at these positions due to gravity and momentum, but direct radial force due to muscle contraction is of questionable value.

Jay Kosta
Endwell NY USA

The problem is when does pulling up start to be more problem than it is worth. Is pulling up at 11 still worthwhile? Or, pushing forward at 2? A serious examination of what the individual muscles do reveals that any given muscle can only provide a force within 45? of the pedal direction for about 90? of the pedal circle. Any more and the applied force is getting closer to radial than tangential. So, when should contraction start and when should it end for each muscle for optimum efficiency/power generation? It surely isn't clear but I think it is clear the average cyclist isn't anywhere near this coordination when they are contracting muscles to apply force opposite to the direction of pedal motion.

 

[FrankDay]

Do you believe or claim that PC's can improve pedalling muscle efficiency ? Muscle efficiency is not the problem in cycling, cyclists don't know how to use them for best results. The ideal pedal stroke should be able to apply continuous peak torque over 180 deg. but that's impossible. The percentage figure worth considering then is how much of that torque can a rider apply in each 180 deg. stroke, this will give the true efficiency of your pedalling.

Depends what you mean by pedaling muscle efficiency. I believe (and Luttrell showed) that PC's can improve cycling efficiency. They cannot improve muscle contractile efficiency of individual muscles beyond what occurs from normal training of muscles.

 

[sciguy]

So, you don't believe the forward forces seen when the pedal is moving backwards shown below, representative of a typical cyclist, represents "working against themselves"?

as apposed to this representation that actually takes into account gravity?

My vote is on #2.

Hugh

 

[JayKosta]

as apposed to this representation that actually takes into account gravity?

My vote is on #2.

Hugh

-----------------------------------------------------
So, does anyone have an opinion about whether overall performance could be improved by making a pedaling technique change in the 180-360 portion to increase 'net muscular power' and decrease 'non muscular power'. The graph seems to show that an attempt is being made to 'unweight' the pedal on the upstroke, but not enough for full unweighting - so some of the other leg's downstroke power is being used raise the upstroke leg.

If the upstroke technique includes inefficient radial muscle contractions as part of the overall 'gross muscular' upstroke effort, then perhaps a technique change could be learned to avoid those contractions - with little or no increase in the amount of 'gross muscular' upstroke effort.

Jay Kosta
Endwell NY USA

 

[FrankDay]

I would certainly agree that one's technique was awful if they were actively working against themselves

Come on Hugh. Look at the illustrated pedal force diagram (which represents typical pedaling pattern of most non-PowerCranks trained cyclists) specifically between 3 and 4:30 o'clock.

The pedal is moving down and to the left but the pedal forces are down and to the right. Those "to the right" forces can only come from active contraction of the quads while the pedal is in this position so we have a pedal moving to the left and an active application of force to the right which definitely constitutes "actively working against themselves" wouldn't you agree? Further, if we subtract the downward component due to gravity and not due to muscle contraction here the "to the right" vector is probably larger than the "downward" muscle vector for much of this time. This technique constitutes "actively working against themselves." Can I get an admission that this an awful technique? since this is representative of how the vast majority of cyclists pedal can I get an admission that I was right that the vast majority of cyclists have awful technique.

Why is it with a pedaling pattern like this that you folks continue to insist that pedaling technique cannot potentially be improved?

I ask again, is there another sport where the technique of beginners and the technique of most experts for the most important aspect of the sport is the same? (not all experts I would submit but at least the experts that have been studied and in the literature.)

Why do most cycling coaches not bother to even try to teach technique? coachfergie has said here he wouldn't waste his or his cyclists time trying. How can anyone examine that pedal force diagram and not conclude there are watts to be gained here?

 

[JamesCun]

-----------------------------------------------------
So, does anyone have an opinion about whether overall performance could be improved by making a pedaling technique change in the 180-360 portion to increase 'net muscular power' and decrease 'non muscular power'. The graph seems to show that an attempt is being made to 'unweight' the pedal on the upstroke, but not enough for full unweighting - so some of the other leg's downstroke power is being used raise the upstroke leg.

If the upstroke technique includes inefficient radial muscle contractions as part of the overall 'gross muscular' upstroke effort, then perhaps a technique change could be learned to avoid those contractions - with little or no increase in the amount of 'gross muscular' upstroke effort.

Jay Kosta
Endwell NY USA

Non muscular power is a fixed number for each athlete. It is the gravity acting on the leg.

 

[JamesCun]

Frank, you've now moved to yet another argument. Guess the last few didn't pan out.

New argument...it just has to be a technique problem since it just doesn't make sense that pros and amateurs have the same economy, I swear, it just has to be so...

 

[acoggan]

Come on Hugh. Look at the illustrated pedal force diagram (which represents typical pedaling pattern of most non-PowerCranks trained cyclists) specifically between 3 and 4:30 o'clock.

Better still, look at the same data after correcting for the non-muscular components (which proves you wrong):

 

[acoggan]

Could you name a single other sport in which the beginners and experts have essentially the same skill and technique for the most important thing they do?

Can you name a single other sport in which the degrees-of-freedom (of motion) are so restricted?

(BTW, I wouldn't suggest putting too much faith in that Jeukendrup et al. paper, as the reported efficiencies are abnormally - almost unbelievably - low.)

 

[FrankDay]

as apposed to this representation that actually takes into account gravity?

My vote is on #2.

Hugh

Hugh, the net power is, of course, positive. However, it would be more positive if the cyclist were not working against himself after 3 o'clock. It is a pretty simple analysis. You are simply refusing to face facts so you don't have to admit you are wrong.

Do you find it a little odd that non-muscular power is negative at 3 o'clock?

One more thing. If you were to eliminate the gravity component and graph the work done around the circle by Peter Vabrousek (I am sure you remember) I posted earlier, that net work line would be pretty much a straight line showing net work was being divided up around the circle pretty well. If you can increase the low parts of the graph why don't you want to since the power generated is the average power around the circle, not the peak. I might add that this rider is about at the same power as Petr in his graph but they have totally different pedaling patterns. I think I will superimpose Petr's pattern on this graph then we can compare as to which looks "better" to the eye test.

 

[FrankDay]

Can you name a single other sport in which the degrees-of-freedom (of motion) are so restricted?

(BTW, I wouldn't suggest putting too much faith in that Jeukendrup et al. paper, as the reported efficiencies are abnormally - almost unbelievably - low.)

How about rifle in the prone position? Horseback riding? Bobsled? Luge? Rowing? There are lots of sports in which the motion of the athlete is limited yet technique is important.

I am sorry. You believe that because the foot motion is restricted to a circle on a bicycle that somehow this means that the coordination for applying power somehow doesn't matter? Do you have a paper that shows this to be true. To me, the fact that the motion is restricted simply means that it is much harder to determine what the coordination being used is and to teach a better coordination, not that it is unimportant. Because it is hard many just feel it is not worth the effort. But, not everyone believes that the coordination that is "natural" is the best one. When Greg Lemond first got on the PowerCranks he told me that he spent years trying to learn how to pedal in this fashion and now people can learn it in months. Carmichael reported that Armstrong worked on his technique specifically to reduce the losses on the backstroke and increase the forces across the top. Coyle documented a 10% increase in efficiency in his cycling during this period. And, then, there are the pros who keep getting on the PowerCranks because their teammates tell them to. SOLD 5 pair to Team Sky members this off season.

There is zero evidence that because the foot motion is restricted that the coordination used to apply power is unimportant. It is hard to evaluate and change, that is why you want it to be unimportant.