While Craig A. may ride that way and still race/run extremely well that alone is not evidence that he could not do better if he reduced his bike cadence some.

The scientific evidence certainly suggests that he would bike more efficiently if he reduced his cadence some and, if that were the case, why wouldn't he then run better if expended less energy on the bike leg.

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Frank,
An original Ironman and the Inventor of PowerCranks

Jesus I can't believe how far this thread has gone. Weekend 1 ride 100 mile at a cadence of 90rpm and do a 4 mile run off the bike. Have a steady week then weekend 2 ride the same course at 70rpm similar effort then run 4 mile off the bike. If unsure do it all over again. If you don't have your answer then just do whatever comes natural on the bike until you are good enough to try again and make your mind up. It would be quicker than reading through all the carp on this thread and the results are specific to you - not some test group or science geek generalising on the theory of pedal pressue.

Geez - get a life................ Its no rocket science.

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He who understands the WHY, will understand the HOW.

Just like Nicko, who is right with every word he wrote, I am shocked about your non-understanding of simple mechanics. There is no way that a rolling "metal biker" with frictionless joints and no air and rolling resistance will produce any energy loss resulting in heat. You can not compare solid metal with rubber tires. If there is any "internal friction" in the metal it is at a very very low level and totally irrelevant.

But of cause in a human biker there are internal energy losses that increase with cadence. The human biker is kind of a mixture of a metal and a rubber biker.

But concerning the question of Chrissies cadence, your argumentation seems solid to me in general.

(I just registered here to take part in this discussion. Because I am German, please forgive me some inaccurancy in my English.)

like frank said, 'why not?'

has CA set any world records lately? no
has he improved? no

as for chrissie not running better the last half of marathon compared to her last two IM's.
as brett said, her IM OZ 09 was her best performance. Roth, she had some stomach issues. Hawaii, who knows.
but remember this is the first year without brett. as she said at a talk on friday, she is on her own and she will make mistakes. so perhaps she made some mistakes. IMO, she needs get rid of dave scott's strength program. saw him at the gym, he has the worst form, i've ever seen. he needs six month of rolfing, and six months of pilates 3x week to get body alignment.

think outside the box, will ya! u guys are conformists. keeping making the same mistakes over again and want better results is called insanity :)))

It turns out you can compare solid metal with rubber tires. The term to compare them for this discussion would be modulus of elasticity. Since no material returns exactly as much energy as was put into it to deform it heat will be generated. It is simply a matter of how much. If one examines the leg one will find that some of it is very stiff like metal (the bone) but the majority of it is something very flexible, much more flexible than rubber (the muscles, fat, and skin). I dare you to take a leg of lamb and swing it up and down similar to the motion of the thigh and tell me it doesn't take any energy. Since that leg of lemb won't be doing any external work I would ask you to then tell me where that energy is going if it isn't being lost as heat.

Anyhow, all I ask you folks that think I am all wet is simply explain to me where the losses occur between the energy contraction efficiency of the muscle (about 40%) to the overall energy efficiency of the cyclist (about 20%). Unless you can explain that drop in efficiency without invoking the losses I am taling about I think I would think twice before you (or anyone else) claim I do not properly understanding this issue.

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Frank,
An original Ironman and the Inventor of PowerCranks

Modulus of elasticity has nothing to do with it. Regardless of modulus of elasticity, an elastic deformation converts work energy to potential energy and back again without loss. In reality there is a small amount of loss, but that's no excuse to throw out the baby with the bathwater; the basic theory still holds. As to the applicability for this discussion, that's another matter...
And you can wave your leg of lamb all day, it will not cook (but you will warm up a lot!). Your challenge to explain the loss of energy should go back to you, since clearly you do not have sufficient grasp of the concepts to explain it.
Not that I'm pleased with everything your opponents have written, either; but they're closer to the mark.
On to another angle: the macro physics level is only one aspect of things. Work done is force integrated over distance from a macro point of view, but we all know that even statically applying a force in the human body requires power. So clearly there are inefficiencies at going at too low a cadence as well as pedalling too high. Determining the sweet spot is far too complex for me. I'm not saying your optimal cadence is wrong; I'm suggesting that you don't have calculations to support it, and in fact that no one has calculations to support it that are based on the macro physics of the thing; I think it's the sort of thing that is so complex that it would have to be determined empirically.

Well, when you combine modulus of elasticity with elastic hysterisis I think you will find it explains the fact that there are losses quite nicely. At least you agree with me that there are losses here. You simply think they are too small to be considered. Where is your data to even suggest what the magnitude of the losses actually are such that you feel they are too small to be considered? Do you feel the drive chain losses are too small to be considered? After all 1-2% is only 2-4 watts at 200 watts. I (and you) know those losses are there. I simply feel these losses have to be relatively large simply because I cannot find enough losses in other mechanisms to explain the totality of the losses without invoking them and their being relatively large.

One correction, statically applying a force by the body requires energy, not power, since no work is done. IMO, this phenomenon does account for some of the efficiency losses because the resultant force on the pedals is rarely tangential to the circle and applying force that does no work can only result in lowering the overall efficiency. I believe this could account for about half the difference in that 20-40% differential. If someone could apply a perfectly tangential pedal force around the entire circle I suspect they could get to a pedaling efficiency of about 30%. Of course, some here have held out that none of this stuff matters. Just ride your bike, don't worry about this efficiency stuff. Well, finally the Foss paper suggests that worrying about efficiency does or can make a difference in performance. These debates will never be the same.

You tried to put the burden on me to explain the losses but I have no trouble explaining the loss of efficiency between the cyclist overall and contracting muscle except I have to invoke losses the due to the pedaling motion I have mentioned to do it. If someone else can show that this loss can be explained totally without invoking a loss simply from the pedaling motion have at it. If this is so simple to explain where are the explanations showing me up for being so stupid?

Oh, and I agree that optimum cadence for anyone person must be determined empirically through testing. The principles are clear, I believe, as to what influences optimum cadence but the interactions and unknowns (muscle fiber type mix) are way to many and complex for any calculation. I think it is enough that people understand there is an optimum cadence for them and that they should endeavor to determine what it is if they want to maximize their performance. Even that seemingly simple idea seems to complex for many here.

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Frank,
An original Ironman and the Inventor of PowerCranks

If you don't realize and admit, that it is complete nonsense to say, that parts of a combustion engine heat up because they are accelerated and decelarated (not plastically bent) by some forces, any further discussion of mechanical issues is worthless.

Frank,
I believe there are sport physiology experimental methods already in place to determine this. I don't know if labs used them.
See the Force-Velocity curves* and the Power-Velocity curves* calculated for individual muscle fiber types. I believe the same measurement should be possible for the whole leg. From there there are a couple more steps to be calculated, but it's feasible. But I bet that's what they do for cycling professionals when they work on records (wind tunnel etc.).

*: Curves taken from pages 28 and 49 of

Bottinelli R, Reggiani C. Human skeletal muscle fibres: molecular and functional diversity. Progress in Biophysics and Molecular Biology. 2000;73(2-4):195-262.

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Giovanni Ciriani
http://www.GlobusSHT.com

Frank, get back to me when you have cooked a leg of lamb by waving it around. Obviously my words are not giving you insight.

P.S. Surely you don't think that rate of energy input is unrelated to power? Tell me you didn't mean that. Also, if 'no work is done', why do you warm up from isometric exercises? Work *is* being done, but it is not at the macro level.

No one is going to cook a leg of lamb by waving it around, the amount of mass and the rate of energy going into it going into it and the rate of convection loss would suggest that the temperature increase would be difficult to detect.

You warm up from isometric exercise because energy is consumed (it is the nature of the biological engine) but no work is done. Work is a scientific definition that requires a force through a distance. No distance, no work.

Get back to me when you have actually considered this problem and can comment with something other than "you don't know what you are talking about". If that is true, prove it by telling us what is the actual case. Account for that efficiency loss between the muscle and the wheel.

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Frank,
An original Ironman and the Inventor of PowerCranks

The problem with this simplistic analysis is it doesn't take into account the fact that pushing on the pedals requires the coordination of several different muscles, each one with a completely different characteristic and some being contracted hard and others easy that are ever changing. Such graphs, however, certainly do point out why cadence may have an effect on efficiency. Above a certain cadence it is impossible for the muscle to apply any force to the pedal regardless of any losses to which I refer.

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Frank,
An original Ironman and the Inventor of PowerCranks

  
Since most people don't race their bikes without a load on the pedals, I think you might want to consider some of these points that Jim Papadapolous made in "Bicycling Science":

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http://bikeblather.blogspot.com/

Well, I would disagree. While it would seem there is "no obvious inefficiency" from this movement, the inefficiency starts to become obvious, it seems to me, as soon as one tries to pedal the unloaded bicycle. There has to be a reason why your HR will go up when you take the chain off the bicycle and try to pedal at at a cadence of 140. The HR goes up because there is an energy cost to the pedaling motion even though there is zero work being done. Simply adding a chain and a little power (a requirement if one is going to allow the chain to slow the legs) wouldn't change that equation, it seems to me, since extra power must now be added to keep the cadence up. How does one explain this? I simply disagree with their analysis. The physics of the pedaling motion must be the same whether the chain is loaded or not loaded.

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Frank,
An original Ironman and the Inventor of PowerCranks

A smart man once said, "When you change something...something changes." :-)

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http://bikeblather.blogspot.com/

Or why net efficiency, although easily calculated, is next-to-impossible to interpret.

Frank, you may insulate your leg of lamb as much as you like. In fact, you can wave around a frozen leg of lamb and measure how much faster it warms up versus passing the same amount of air over a similar, unwaved leg.

I should have qualified my statement about isometrics: yes, the complexity of 'the biological engine' did not make for a great example. Nevertheless, I am still baffled that energy is consumed by 'the biological engine' and yet it is fueled without power. That is a marvel!

I have a couple of problems with your 'get back to me' comment. First, it assumes that your restatement of the real problem (you want to look at inefficiency rather than optimal cadence) is legitimate. I reject that. The onus is on you to demonstrate the relevance. I've already told you that I can't explain it all, as it is too complex a question, so I don't know why you're demanding the answer to an irrelevant question that you know I can't answer. Second, I don't need the credentials of having the exhaustive explanation you wish for to know that certain explanations *cannot be*, so please stop with the 'oh yeah, well what is it then' tack. When you get called on throwing out terms in ignorance (modulus of elasticity is just one), just admit that you don't have a solid grasp of the subject matter at hand instead of talking as if others were somehow negligent for not doing your own homework (correctly) for you.

Get back to us when the mutton's ready... :-)

Let us assume that it is possible to transfer all that energy put into the accelerating the thigh into the pedal to drive the bicycle to decelerate the thigh. Only problem is that only works if the person actually causes it to happen. For this to happen there has to be a forward driving pressure of the foot on the pedal (so the pedal can have a reactive slowing force to the foot). This is really easy on the downstroke but I challenge you to show me anywhere that this occurs on the upstroke, except in the PowerCranks trained rider and then only in those PowerCranks trained riders who do more than simply unweight.

So, while in theory, it might be possible for all this energy to be transferred to the bicycle (it might be in space where there is no interference from the effects of gravity) there is simply zero evidence that it actually occurs in everyday cycling, at least completely as described by Papadapalous in 'Bicycling Science'. Hence, it would appear that this kinetic energy may be partially transmitted to the bike (from the downward moving leg) but not at all from the upward moving leg. That "untransferred" energy must be lost somewhere. Tell me where it is going. Unless there is forward pressure against the pedal when the thigh is slowing it is impossible to transfer the kinetic energy contained in the thigh to the pedal. Perhaps that is one of the mechanisms that allow PowerCranks to achieve such large increases in power. :-)

Again, please describe for me where all the losses are to account for the drop in efficiency from the contracting muscle to the wheel. If one cannot account for all the losses one doesn't understand what is going on during pedaling.

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Frank,
An original Ironman and the Inventor of PowerCranks

No it is not, it is a simply because of the accepted definition of power. No movement, no power.[/reply]
I have a couple of problems with your 'get back to me' comment. First, it assumes that your restatement of the real problem (you want to look at inefficiency rather than optimal cadence) is legitimate. I reject that. The onus is on you to demonstrate the relevance. I've already told you that I can't explain it all, as it is too complex a question, so I don't know why you're demanding the answer to an irrelevant question that you know I can't answer. Second, I don't need the credentials of having the exhaustive explanation you wish for to know that certain explanations *cannot be*, so please stop with the 'oh yeah, well what is it then' tack. When you get called on throwing out terms in ignorance (modulus of elasticity is just one), just admit that you don't have a solid grasp of the subject matter at hand instead of talking as if others were somehow negligent for not doing your own homework (correctly) for you.

Get back to us when the mutton's ready... :-)[/reply] If you accept that it is a very complex question and that you don't understand it why are you here arguing as if you do?

If you think it is irrelevant to racing trying to understand where half the energy being put into pedaling is being lost before it gets to the wheel so be it. I think it is relevant because if we can understand where the losses are perhaps we can devise better ways of minimizing them to get more power to the wheel.

As they say, ignorance is bliss.

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Frank,
An original Ironman and the Inventor of PowerCranks

So...tell me, when you throw a ball into the air and it decelerates to zero and then starts moving downward again...where did that energy go?

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http://bikeblather.blogspot.com/

That is easy, the potential energy is being changed into kinetic energy (or vice versa). The total energy of the system remains constant less the frictional (heat) losses as it moves through the air (usually too small to heat a leg of lamb though unless the ball is a satellite reentering the atmosphere).

Read Papadapolous again. The total energy of the pedaling system does not remain constant. Therefore there must be a constant energy input and output from the system to keep it going.

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Frank,
An original Ironman and the Inventor of PowerCranks

 
You're talking in circles again (pun intended)...I give up...(what was I thinking?) But, to help you out a little more, here's some more Jim P.:






Hey! Now there's an idea for REALLY making your cranks train a completely tangential pedal force application. Make the pedal attachment run in a radial slot along the crank arm! The rider would be forced to ONLY pedal tangentially since transferring force to the crank except in the tangential direction would be impossible!

Make sure you credit Jim for the idea when you implement it ;-)

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http://bikeblather.blogspot.com/

I have heard that idea before about training the tangential force. You are welcome to try to carry it off if you desire. Of course, the problem is that tangential forces are not particularly helpful unless they are positive. I really think the new force measuring pedals will help riders achieve this goal without the need for such a mechanical device that will surely be prone to sticking and not working very well.

(Edit: I might add he is only theorizing that training someone to pedal in completely tangential circles would be less powerful. Eccentric muscle contractions can actually increase efficiency in certain applications. If less energy is used ensuring the forces are tangential than is lost in applying force non-tangentially then there would be an overall benefit. Since one the feet are attached to the pedals I suspect one would eventually learn the proper coordination and to make it very energy efficient (minimizing the need for eccentric contractions). One cannot know the outcome unless one actually tests the concept. As with PowerCranks it would take a period of time to actually train someone to ride in that fashion and then test the difference.)

Anyhow, as I stated before, the theory by Papadapolous as to how the kinetic energy of the thigh is transferred to the pedals to prevent these losses from occurring cannot be true without their being positive forces on the pedals (of sufficient magnitude to transfer all the necessary energy) when the thigh is decelerating. Since that doesn't happen on the upstroke between 9 and 12 (in most people the forces there are negative) his theory for energy conservation during pedaling cannot be true.

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Frank,
An original Ironman and the Inventor of PowerCranks

One more thing. Look at the pedal forces shown in the above diagram. the forces of the passive rider whose legs are being driven around the circle. If the slowing of the thigh was really transferring energy to the pedals we would expect to see it here yet it doesn't even occur on the downstroke, probably because the speed of the pedal is moving away from the foot faster than gravity is trying to accelerate the thigh. His theory requires the energy contained in the rapidly moving thigh to be transferred to the pedal as the thigh slows. It simply doesn't happen on either side of the pedal stroke.

Me thinks he needs to rethink his theory because he simply doesn't have any data to support that what he thinks happens actually occurs in real life. I think everything would be different if we were riding in space, where there is no gravity. Unfortunately, that doesn't apply to most of us.

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Frank,
An original Ironman and the Inventor of PowerCranks

I'm sorry...that part should've been in pink...



Like that ball I talked about earlier...isn't gravity a force ALSO acting on that thigh moving upward as well? Force to the mass isn't being applied through the pedal only.

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http://bikeblather.blogspot.com/