Powercranks

[Phil Holman]

"Andy Coggan" <[email protected]> wrote in message
news:[email protected]...
> "Phil Holman" <[email protected]> wrote in message
> news:[email protected]...
> >
> > "Andy Coggan" <[email protected]> wrote in message
news:b89Xb.2642
> >
> > > As Andrew Bradley has explained to you (and explained to you, and explained to you, and
> > > explained to
> > you), NO -
> > > none, zero, nada, zip - energy is lost simply due to the legs
going
> > 'round
> > > and 'round. Rather, ALL - every little bit - of the energy loss
occurs
> > > BEFORE the energy is transferred to the limb segments in the first
> > place
> > > (this loss being due to the viscoelastic elements in muscle).
> >
> > The weights used on the legs resulted in significant energy
increases
> > and is an indication that the losses due to just the legs going around are
not
> > nada.
> >
> > http://tinyurl.com/24qxc
>
> No it does not, as adding additional mass to the legs could also increase energy loss to
> viscoelastic elements. The only way to determine where the energy loss occurs is to perform what
> is called an inverse dynamic analysis - this requires not only knowledge of the rates and
> directions of limb movements and their masses (what Frank has attempted to model based on assumed
> values), but also knowledge of power flow to the pedals. It is the latter that he did not include
> in his calculations (because
he
> lacks the data, having never used a force pedal in his life), which is why his conclusions are
> incorrect (and, in fact, impossible, since they violate the laws of thermodynamics). If, however,
> you account for energy transfer to the pedals, you find that there is complete conservation of the
> kinetic and potential energy invested in the limbs as a result of muscle contraction (as you would
> expect based on simple physics). Ergo, any and all energy loss MUST occur BEFORE the limbs begin
> to move in the first place
> - which is exactly as you would expect, given the nature of biological materials (i.e., the
> molecular "motors" of muscle and the properties of connective tissue, tendons, and ligaments).

Essentially the same thing where the losses are what you would expect from a reciprocating non-rigid
mechanism. The setup is not fully constrained either, laterally or in-plane with spherical joints at
2 locations and one too many joints (the ankle). All this must require input from the rider to keep
it together and running. An engineered mechanical device would drop it's heel at the bottom of the
stroke and the knee joint would lock up.

Phil Holman

 

[Frank Day]

"Andy Coggan" <[email protected]> wrote in message news:> > If you want
> > to impress me, improve you best 40K TT by 1 mph.
>
> Different situation: I've been optimizing my training for TTs for years, and so there's little, if
> any, room for further improvement. In contrast, you (if I understand things correctly) went from
> racing on the road to preparing for a <3 min event, and in the process changed your training
> around radically.

You only think you have been optimizing your training for TT. This would only be true if it can be
proven that it is not possible to go any faster. I still claim PowerCranks could increase your speed
in the 40k TT 1 mph (probably more like 2-3 but that would take a little longer and you would, of
course, have to use them as i say) but you are afraid to try because if I am right, everything you
have said here would be proven wrong.

Frank

 

[Frank Day]

"Andrew Bradley" <[email protected]> wrote in message news:<2_4Yb.5847$Y%[email protected]>...
> Frank Day <[email protected]> wrote in message
> news:[email protected]...
>
> > Look, from my (as I have recently come to understand) uninformed background it is really quite
> > simple. There are several things that come into play (which makes it not quite so simple in
> > practice). What is the energy use (what are the demands for oxygen by the mitochondria that are
> > making energy molecules necessary for muscle contraction?) that needs to be made up. What is the
> > furthest distance that oxygen must diffuse from the end capillary (where oxygen concentration is
> > lowest) to one of these active mitochodria. And, how much oxygen is in the blood (hemogglobin
> > concentration) which determines how fast it will drop as it passes through the capillaries. As
> > demand in the muscles increase, additional capillaries will open up, reducing the distance from
> > the active capillaries to to the mitochodria. Once they are all opened and once the
> > concentration at the end capillary drops to a point that the diffusion gradiant to the furthest
> > away mitochodria is not sufficient to supply the necessary amount of oxygen then anaerobic
> > metabolism ensues in that mitochondria (LT) and any additional effort just makes it worse and
> > the end is near.
>
> Do you feel that, with increasing intensity, there comes a point where the upstoke mitochondria
> are easier to supply with extra oxygen than the downstoke mitochondria?

The mitochondria don't know or care if they are in upstroke or downstroke muscles. It makes no
difference whatsoever. All that matters is how hard you are trying to work those muscles compared to
how well they have been trained. That is the key as to how "hard" or "easy" it is to supply those
mitochondrias with oxygen.

Frank

 

[Frank Day]

"Andy Coggan" <[email protected]> wrote in message news:> > > It's simple:
> > >
> > > 1) VO2max = the highest attainable rate of O2 uptake, limited by maximal cardiac
> > > output/convective O2 delivery.
> > >
> > > 2) VO2peak = anything less than true VO2max, even if it is the highest
> that
> > > that person can achieve given the exercise modality. Limited by the inability to recruit
> > > (actually, sufficiently vasodilate) enough muscle
> to
> > > drive cardiac output all the way to maximum.
> > >
> > > Since trained cyclists can achieve a true VO2max while cycling, all of
> your
> > > claims with regards to muscle mass are moot, at least when talking about sustainable power
> > > output (the energy for which must be derived
> aerobically).
> >
> > I believe you misinterpret what VO2 max means.
>
> Yes, I need an anesthiologist-turned-inventor to explain it to me.

Perhaps you could give me (and those who are still here) a reference to a standard textbook that has
the definition of VO2 max to include: ", limited by maximal cardiac output/convective O2 delivery."

>
> > It is not the highest possible VO2 uptake that could ever be attained by this individual. It is
> > the highest attainable VO2 by that individual in his/her current state of training.
>
> I thought that was implied in what I wrote.

What you have been writing cold be interpreted wither way as you seem to think that it is not
possible to increase VO2 max by training additional muscles.

>
> > By virtue of your definition of VO2 Peak, it seems to me that you are accepting that VO2 uptake
> > (and, hence, VO2 max) depends greatly on the amount of muscle mass that is recruited.
>
> That's why it is called a VO2peak and not VO2max: VO2peak *is* muscle mass dependent, e.g., I
> can't reach VO2max by twiddling my thumbs, so the highest rate of VO2 that I can achieve during
> that form of exercise would rightfully be called a VO2peak.

And you can't reach VO2 max by just pushing on the pedals. At least it certainly isn't intuitive nor
is is proven in the literature, except, perhaps, in your own mind.
>
> > Further, how on earth does one know one has actually tested "true" VO2 max as you define it.
>
> So many studies have been done looking at this issue that people simply accept that the highest
> VO2 a person can achieve during uphill running is really VO2max, and not a VO2peak.
>
> > These tests are always effort dependant and never truly objective.
>
> That's simply not true. The majority of individuals* show a plateau in VO2 during high intensity
> exercise, meaning that even if they summon up the extra motivation to keep going, it doesn't alter
> the measurement of VO2max.

If one defines VO2 max as the VO2 uptake when a plateau is reached then such a definition is
reasonably objective as long as the plateau is readily obvious. Unfortunately, such obviousness is
hardly ever present.
>
> *Depending on how the test is designed, of course.

and the definitions used.
>
> > To say that cyclists can attain "true" VO2 max goes against the facts as I understand them as I
> > understand that triathletes frequently will have higher measured VO2 max running than when
> > cycling. Of course, in your mind triathletes are not "trained cyclists" which would explain this
> > discrepancy. That is not a sufficient explanation to me.
>
> What more explanation do you want? It takes a certain amount of specific training to be able to
> achieve a true VO2max while cycling, and most triathletes apparently don't reach this level. OTOH,
> there are a few swimmers who can achieve a true VO2max while swimming, despite relying almost
> exclusively on their upper body muscles.

Are you saying Swimmers are adjudged as reaching true VO2 max because they may take in as much
oxygen swimming as they do when running uphill. Does that surprise anyone? Has anyone ever taken in
more oxygen doing their sport than they take in running uphill? If this is the definition of "true"
VO2 max, I submit it is flawed. It only takes one exception to prove it worthless. How about an
athlete with cerebral palsy. Does the definition hold for them also?

It is possible to have pretty robust aerobic capaicty in the upper extremities and pretty puny
aerobic capacity in the lower extremities (wheelchair athletes come to mind) What constitutes a true
VO2 max in an elite wheel chair athlete.

All this can lead to a basis for discussion but such pronouncements as this represents a "true" VO2
max are hardly absolute.

Frank

 

[Frank Day]

"Andy Coggan" <[email protected]> wrote in message news:<[email protected]>...
> "Frank Day" <[email protected]> wrote in message
> news:[email protected]...
> > "Andy Coggan" <[email protected]> wrote in message
> news:<[email protected]>...
> > > "Frank Day" <[email protected]> wrote in message
> > > news:[email protected]...
> > >
> > > > take the drive train away. The losses are there whether there is a chain attached or not.
> > > > Put your bike on a stand and take the chain off and pedal at a cadence of 130 (or the
> > > > highest cadence you can sustain) and see if your HR increases. See how long you can do it.
> > > > If it doesn't take any energy why does your HR change (or mayby yours won't). Try it and
> > > > report back.
> > >
> > > This experiment is a red herring, since it fails to differentiate
> between
> > > energy losses due to the properties of biomaterials vs. those that might have a physical basis
> > > on a larger scale. As Andrew Bradley has explained
> to
> > > you (and explained to you, and explained to you, and explained to you),
> NO -
> > > none, zero, nada, zip - energy is lost simply due to the legs going
> 'round
> > > and 'round. Rather, ALL - every little bit - of the energy loss occurs BEFORE the energy is
> > > transferred to the limb segments in the first place (this loss being due to the viscoelastic
> > > elements in muscle). Efficiency
> is
> > > therefore a complex function of cadence, and can't be predicted using
> your
> > > simplistic calculations that ignore energy transfer to the pedals (and
> in
> > > the process, violate Newtonian physics).
> >
> > I'll "accept" your erudite explanation of where the losses are if you will accept that there are
> > losses and they vary with the cadence
>
> Of course. But the point is that you don't even understand basic physics enough to realize that
> you can't calculate them using your simple model that ignores reality, i.e., the fact that the
> energy must go somewhere (into the pedals).

Your "energy must go somewhere so it goes into the pedals" system only works when the angular
velocity is not constant. When these forces go into the pedals and the pedals can change angular
velocity then the energy is transferred and then it can be transferred back when it needs to come
back. However, if the angular velocity is constrained to be constant then your system breaks down.
But, wait you argue, pedaling cadence really isn't constant as the whir whir whir sound of the
trainer lets us know. I would accept that argument except in the real world the accelerations are
occuring on the downstroke/upstroke and not at the top and botton where it would have to occur to
satisfy your reasoning.
>
> > raised anywhere from the 3rd to the 4th power.
>
> Since the inefficiencies are a complex function of biochemistry, biomechanics, etc., there's no
> reason to expect that they will conform to any fixed function.

There isn't. Sounds to me like obfuscation by using jargon and this is too complicated for you to
understand reasoning.

>
> > Just one question though, since we have two sets of data indicating these loses are not small
> > and not directly related to cadence (Phils's numbers and the other study he gave the data from)
> > please explain to me how viscoelastic losses vary with the cube or 4th power of the cadence?
>
> See above.
>
> >I missed that in physics class.
>
> It isn't really a physics problem, at least not entirely (or unless you want to think of it as
> biophysics). You could *try* to model pedaling using limb segments of appropriate masses, power
> transfer to the pedals, and springs and dampers to reflect the viscoelastic properties of muscle,
> but I don't know how well you could do so (a simple mass-on-a-spring model works pretty well for
> upright locomotion, though).

I guess not, it is a thermodynamics problem.

Frank

 

[Andrew Bradley]

[email protected] (Frank Day) wrote in message news:<[email protected]>...
> >
> > Your analysis is roughly correct, the low in energy occurs roughly at TDC/BDC, and the high at
> > mid stroke, so you fit a traditional elliptical to speed the legs up over tops and slow them
> > down mid stroke. Energy variation is reduced. What more do you want Frank???
>
> What more do I want? I simply want to to show me how such a speed variation can make the energy
> variation go to zero. I don't deny that such a device could reduce the variation. If you can't
> make it zero though, then my theory still holds.

So you have twigged at long last (thanks for admitting to it). Your calcs are chainring dependent.

No more proof is required. (From what you wrote earlier I understand your alarm bells work well
enough to tell you these rings don't address the real issue - although it wouldn't surprise me if
you now changed your opinion).

> > >it can't be done as far as I am concerned so even if all the viscoelastic losses and bearing
> > >losses are zero, this is cannot be a perpetual motion machine.
> >
> > You presumably feel that some form of osmosis to the ether accounts for the energy loss. Chain
> > off, your model _is_ a perpetual motion machine (note the word "model").
>
> No, the lost energy is lost as heat as all all inneficiencies in the real world.

Osmosis of heat then?

> > >Just account for the thighs please and I will come over to the dark
> > side.
> >
> > The "energy saver" ring slows the thighs down where they move fastest. But don't overlook the
> > lower leg Frank, and don't overlook shoes, pedals and cranks.
>
> No, they can be pretty much overlooked. The feet move in, essentially, exact circles so their
> accelerations are always equal and opposite, they conserve energy.

Opposite accelerations cancel in a kinetic energy calculation???? To quote a previous poster: Wrong,
wrong, wrong, wrong and wrong. Pedal speed is what counts here.

With variable pedal speed (eg funny ring or hill climbing), foot, pedal and crank energy _does_vary
and can be made to vary enough to nullify total energy variation. As I said, if you don't like the
shape of the funny ring, make the pedal/crank heavier.

>
> > Consider this: if the funny ring that gives zero mechanical energy variation turns out to be
> > impractical, fit heavier pedals - the chainring can then be rounder. By increasing pedal weight,
> > the energy-saver can in theory be as round as you want.
>
> Changing pedal weight does nothing because they move in exact circles and conserve energy.

So it's to do with the shape of the path rather than pedal speeds, is it?

As I attempted to suggest earlier, why not quietly drop this topic - it isn't anything to do with
the PC case. Before you say something embarassing.

Andrew Bradley

 

[Andrew Bradley]

Frank Day <[email protected]> wrote in message
news:[email protected]...

> > Do you feel that, with increasing intensity, there comes a point where
the
> > upstoke mitochondria are easier to supply with extra oxygen than the downstoke mitochondria?
>
> The mitochondria don't know or care if they are in upstroke or downstroke muscles. It makes no
> difference whatsoever. All that matters is how hard you are trying to work those muscles compared
> to how well they have been trained. That is the key as to how "hard" or "easy" it is to supply
> those mitochondrias with oxygen.

So as regards PCs, what is the upshot of this oxygen delivery debate, even if AC were wrong?

I think I understand that you believe that the aerobic capacity of the upstroke muscles is easier to
develop than that of the downstroke muscles for a typical rider. Is there a reference for that or is
it intuition?

Andrew Bradley

 

[Andrew Bradley]

Frank Day <[email protected]> wrote in message
news:[email protected]...
> "Andy Coggan" <[email protected]> wrote in message
news:<[email protected]>...
> > > I'll "accept" your erudite explanation of where the losses are if you will accept that there
> > > are losses and they vary with the cadence
> >
> > Of course. But the point is that you don't even understand basic physics enough to realize that
> > you can't calculate them using your simple model
that
> > ignores reality, i.e., the fact that the energy must go somewhere (into
the
> > pedals).
>
> Your "energy must go somewhere so it goes into the pedals" system only works when the angular
> velocity is not constant. When these forces go into the pedals and the pedals can change angular
> velocity then the energy is transferred and then it can be transferred back when it needs to come
> back. However, if the angular velocity is constrained to be constant then your system breaks down.

This is the mechanics of the madhouse. Let's escape to the real world. Read Phils excellent summary
of the situation (copied below) then come back and tell us how your no-resistance energy
calculations account for the losses ( ignore the ankle joint if it is too problematic).

"... the losses are what you would expect from a reciprocating non-rigid mechanism. The setup is not
fully constrained either, laterally or in-plane with spherical joints at 2 locations and one too
many joints (the ankle). All this must require input from the rider to keep it together and running.
An engineered mechanical device would drop it's heel at the bottom of the stroke and the knee joint
would lock up."

Andrew Bradley

 

[Frank Day]

[email protected] (Andrew Bradley) wrote in message news:<[email protected]>...
> [email protected] (Frank Day) wrote in message
> news:<[email protected]>...
> > >
> > > Your analysis is roughly correct, the low in energy occurs roughly at TDC/BDC, and the high at
> > > mid stroke, so you fit a traditional elliptical to speed the legs up over tops and slow them
> > > down mid stroke. Energy variation is reduced. What more do you want Frank???
> >
> > What more do I want? I simply want to to show me how such a speed variation can make the energy
> > variation go to zero. I don't deny that such a device could reduce the variation. If you can't
> > make it zero though, then my theory still holds.
>
> So you have twigged at long last (thanks for admitting to it). Your calcs are chainring dependent.

No, they are constant angular velocity dependent. This is the normal condition when one is riding a
bicycle. One can pedal at a constant angular velocity with no chain ring and most people would I
suspect, constraining motion to what feels "normal" to them.
>
> No more proof is required. (From what you wrote earlier I understand your alarm bells work well
> enough to tell you these rings don't address the real issue - although it wouldn't surprise me if
> you now changed your opinion).

The real issue is what are the losses when one is pedaling a bicycle, which means, essentially,
constant angular velocity of the pedals not how small can the losses be under unrealistic condtions
>
> > > >it can't be done as far as I am concerned so even if all the viscoelastic losses and bearing
> > > >losses are zero, this is cannot be a perpetual motion machine.
> > >
> > > You presumably feel that some form of osmosis to the ether accounts for the energy loss. Chain
> > > off, your model _is_ a perpetual motion machine (note the word "model").
> >
> > No, the lost energy is lost as heat as all all inneficiencies in the real world.
>
> Osmosis of heat then?

No, it is lost by conduction and convection mostly.
>
>
> > > >Just account for the thighs please and I will come over to the dark
> > > side.
> > >
> > > The "energy saver" ring slows the thighs down where they move fastest. But don't overlook the
> > > lower leg Frank, and don't overlook shoes, pedals and cranks.
> >
> > No, they can be pretty much overlooked. The feet move in, essentially, exact circles so their
> > accelerations are always equal and opposite, they conserve energy.
>
> Opposite accelerations cancel in a kinetic energy calculation???? To quote a previous poster:
> Wrong, wrong, wrong, wrong and wrong. Pedal speed is what counts here.
It is more than speed. Momentum must be conserved and momentum is a vector. For the feet, this is
really nothing more than a spinning disk, which would go on forever unless there is friction in
the bearings

>
> With variable pedal speed (eg funny ring or hill climbing), foot, pedal and crank energy
> _does_vary and can be made to vary enough to nullify total energy variation. As I said, if you
> don't like the shape of the funny ring, make the pedal/crank heavier.
>
> >
> > > Consider this: if the funny ring that gives zero mechanical energy variation turns out to be
> > > impractical, fit heavier pedals - the chainring can then be rounder. By increasing pedal
> > > weight, the energy-saver can in theory be as round as you want.
> >
> > Changing pedal weight does nothing because they move in exact circles and conserve energy.
>
> So it's to do with the shape of the path rather than pedal speeds, is it?
>
> As I attempted to suggest earlier, why not quietly drop this topic - it isn't anything to do with
> the PC case. Before you say something embarassing.

I am arguing about the real world losses when riding a bicycle. If the mass of the thigh is four
times the mass of the lower leg then pedal speed would have to be approximately 4 times greater at
the top and bottom than on the upstroke and downstroke to conserve momentum. I doubt such a
contraption that would do such a thing would be approved by the UCI. Because of the differing masses
of these particular elements it is not possible to conserve momentum or energy or anything else
while pedaling at a constant pedaling speed. AC argues that the extra energy is tranaferred to the
pedal, which could be true, but if it is it is then further transferred to the chain, wheel, tire
and road and then lost to the system and cannot be retrieved when needed to put back into the thigh
because of the freewheel. Therefore, additional energy is required from the muscles to maintain the
pedaling motion.

Frank

 

[Frank Day]

"Andrew Bradley" <[email protected]> wrote in message news:<[email protected]>...
> Frank Day <[email protected]> wrote in message
> news:[email protected]...
> > "Andy Coggan" <[email protected]> wrote in message
> news:<[email protected]>...
> > > > I'll "accept" your erudite explanation of where the losses are if you will accept that there
> > > > are losses and they vary with the cadence
> > >
> > > Of course. But the point is that you don't even understand basic physics enough to realize
> > > that you can't calculate them using your simple model
> that
> > > ignores reality, i.e., the fact that the energy must go somewhere (into
> the
> > > pedals).
> >
> > Your "energy must go somewhere so it goes into the pedals" system only works when the angular
> > velocity is not constant. When these forces go into the pedals and the pedals can change angular
> > velocity then the energy is transferred and then it can be transferred back when it needs to
> > come back. However, if the angular velocity is constrained to be constant then your system
> > breaks down.
>
> This is the mechanics of the madhouse. Let's escape to the real world. Read Phils excellent
> summary of the situation (copied below) then come back and tell us how your no-resistance energy
> calculations account for the losses ( ignore the ankle joint if it is too problematic).
>
> "... the losses are what you would expect from a reciprocating non-rigid mechanism. The setup is
> not fully constrained either, laterally or in-plane with spherical joints at 2 locations and one
> too many joints (the ankle). All this must require input from the rider to keep it together and
> running. An engineered mechanical device would drop it's heel at the bottom of the stroke and the
> knee joint would lock up."

I don't know what constraints he put on the system he is describing. It sounds like he is trying to
build a mechanical man which presents some difficulty. It is also not clear what masses he used for
the different elements and whether he constrained the pedal velocity to be constant. If he didn't do
the later then this is not a real world model and i don't care what he "expects" because it has
nothing to do with the real world cycling

I didn't try to do this. i started with constant pedal velocity, made assumptions regarding the mass
and size of the various elements and calculated the energy variations in the legs. These would be
the same whether the rider put force into the pedals or not as knowing pedal forces is not necessary
to do the calculations.

Frank

 

[Phil Holman]

"Frank Day" <[email protected]> wrote in message
news:[email protected]...
> "Andrew Bradley" <[email protected]> wrote in message
news:<[email protected]>...
> > Frank Day <[email protected]> wrote in message
> > news:[email protected]...
> > > "Andy Coggan" <[email protected]> wrote in message
> > news:<[email protected]>...
> > > > > I'll "accept" your erudite explanation of where the losses are
if you
> > > > > will accept that there are losses and they vary with the
cadence
> > > >
> > > > Of course. But the point is that you don't even understand basic
physics
> > > > enough to realize that you can't calculate them using your
simple model
> > that
> > > > ignores reality, i.e., the fact that the energy must go
somewhere (into
> > the
> > > > pedals).
> > >
> > > Your "energy must go somewhere so it goes into the pedals" system
only
> > > works when the angular velocity is not constant. When these forces
go
> > > into the pedals and the pedals can change angular velocity then
the
> > > energy is transferred and then it can be transferred back when it needs to come back. However,
> > > if the angular velocity is
constrained to
> > > be constant then your system breaks down.
> >
> > This is the mechanics of the madhouse. Let's escape to the real world. Read Phils excellent
> > summary of the situation (copied below) then come back and tell us how your no-resistance energy
> > calculations account for
the
> > losses ( ignore the ankle joint if it is too problematic).
> >
> > "... the losses are what you would expect from a reciprocating non-rigid mechanism. The setup is
> > not fully constrained either, laterally or in-plane with spherical joints at 2 locations and one
> > too many joints (the ankle). All this must require input from the rider to keep it together and
> > running. An engineered mechanical device would drop it's heel at the bottom of the stroke
and
> > the knee joint would lock up."
>
> I don't know what constraints he put on the system he is describing. It sounds like he is trying
> to build a mechanical man which presents some difficulty. It is also not clear what masses he used
> for the different elements and whether he constrained the pedal velocity to be constant. If he
> didn't do the later then this is not a real world model and i don't care what he "expects" because
> it has nothing to do with the real world cycling

Unlike a mechanical linkage (which wouldn't work) most real people keep the ankle joint rigid by
tensing or relaxing the muscles of the lower leg. This does zero work in turning the pedals but if I
interpret AC correctly, costs nada in metabolic expenditure unless he is including it in some other
loss category. I was looking at a model of the knee joint in action . Good luck with that.

>
> I didn't try to do this. i started with constant pedal velocity, made assumptions regarding the
> mass and size of the various elements and calculated the energy variations in the legs. These
> would be the same whether the rider put force into the pedals or not as knowing pedal forces is
> not necessary to do the calculations.
>
Just to keep the thread going, take a look at what was done in this study.........
http://tinyurl.com/24sph

The difference between mechanical work and energy expended would be all other losses and
inefficiencies no doubt. Apparently it would be hubris to assume modeling implies understanding.
Modeling implies modeling.

Phil Holman

 

[Andrew Bradley]

Frank Day <[email protected]> wrote in message
news:[email protected]...

> I am arguing about the real world losses when riding a bicycle. If the mass of the thigh is four
> times the mass of the lower leg then pedal speed would have to be approximately 4 times greater at
> the top and bottom than on the upstroke and downstroke to conserve momentum. I doubt such a
> contraption that would do such a thing would be approved by the UCI.

Just for the record, according to the calculations of the (eminent) researchers (peer-reviewed etc)
pedal speed would be less than 2/3 higher at TDC/BDC as compared to mid-stroke. This is for an
average rider with normal pedals/cranks pedalling at 90RPM ("instantaneous cadence" varies between
70rpm and 115rpm) .

As i said, if you don't like the idea of such a pedal-speed difference, fitting heavier
pedals/cranks will allow a rounder ring to work the same miracle. I don't see why the UCI would ban
what is only an elliptical chainring and I don't think they'd assume that the cost of pedalling had
disappeared, would you?

Andrew Bradley

 

[Frank Day]

"Andrew Bradley" <[email protected]> wrote in message news:<HEGYb.6877$Y%[email protected]>...
> Frank Day <[email protected]> wrote in message
> news:[email protected]...
>
> > I am arguing about the real world losses when riding a bicycle. If the mass of the thigh is four
> > times the mass of the lower leg then pedal speed would have to be approximately 4 times greater
> > at the top and bottom than on the upstroke and downstroke to conserve momentum. I doubt such a
> > contraption that would do such a thing would be approved by the UCI.
>
> Just for the record, according to the calculations of the (eminent) researchers (peer-reviewed
> etc) pedal speed would be less than 2/3 higher at TDC/BDC as compared to mid-stroke. This is for
> an average rider with normal pedals/cranks pedalling at 90RPM ("instantaneous cadence" varies
> between 70rpm and 115rpm) .

If, in fact, such caculations have already been published in peer reviewed journals why on earth is
AC insisting the losses are "nada" or daring us to point to one article that contradicts a single
thing he has said? If you knew about this article, why on earth were you agreeing with him?

So, my estimates of the masses were different than theirs. Let us accept their numbers. My concept
is still completely valid. It is what I have been saying all along, if the pedal velocity is
constant (real world) substantial losses are involved in the pedaling stroke and these losses
increase with the cadence to some power (depending upon what one is measuring, energy or power).

>
> As i said, if you don't like the idea of such a pedal-speed difference, fitting heavier
> pedals/cranks will allow a rounder ring to work the same miracle.

No, it won't. The pedals move in perfect circles and perfectly balance each other. They cannot
account for any of these energy variations occuring in the legs. One could change this ratio
however by strapping weights to the lower leg. Boy, that would be popular with cyclists, strap 3-5
kg to each leg.

There is another thing the rider can do to minimize this loss that doesn't involve weights or
varying pedal speed. That is to mount their cranks at 90 degrees to each other. In this
configuration one thigh is accelerating when the other is decelerating so the energy could be
transferred from one to the other through the BB. While these accelerations and decelerations are
not perfectly timed, they are close enough that it should get these losses much smaller.
Unfortunately, in order to do this one must be able to actually pedal in a complete circle because
one can't help the other leg over the top by pushing down as at some point both feet are coming up
at the same time. While this does require some external energy to increase the potential energy of
the legs during this portion of the stroke it is all recovered on the down stroke so doesn't require
any net energy.

> I don't see why the UCI would ban what is only an elliptical chainring and I don't think they'd
> assume that the cost of pedalling had disappeared, would you?

Perhaps not. Why don't you build one and market it. It should substantially increase power so it
should sell like hotcakes, assuming people can actually pedal in such a fashion and they like it. Of
course, you would have to deal with AC saying it is just another gimmick and couldn't possibly work
because the losses are "nada" already and, in addition, he is already "optimally" trained so he
wouldn't benefit from it so there would be no need to study it.

Frank

 

[Andrew Bradley]

Frank Day <[email protected]> wrote in message
news:[email protected]...

> > Just for the record, according to the calculations of the (eminent) researchers (peer-reviewed
> > etc) pedal speed would be less than 2/3
higher
> > at TDC/BDC as compared to mid-stroke. This is for an average rider with normal pedals/cranks
> > pedalling at 90RPM ("instantaneous cadence" varies between 70rpm and 115rpm) .
>
> If, in fact, such caculations have already been published in peer reviewed journals why on earth
> is AC insisting the losses are "nada" or daring us to point to one article that contradicts a
> single thing he has said? If you knew about this article, why on earth were you agreeing with him?

I have ranted that these calculations mean little long before this thread. I assume AC agrees with
all right thinkers that , "the internal work method is theoretically flawed" . In view of his
reaction to your ideas though , I'd say that he may need to knock a few heads in his own community,
just to show he isn't biased

Anyway, I told you about this paper from the word go and you agreed with me that pedalling cost
could not be eliminated via a chainring. So who's side are you on?

> > I don't see why the UCI would ban what is only an elliptical chainring
and I
> > don't think they'd assume that the cost of pedalling had disappeared,
would
> > you?
>
> Perhaps not. Why don't you build one and market it. It should substantially increase power so it
> should sell like hotcakes, assuming people can actually pedal in such a fashion and they like it.

Why did the researchers themselves not market the idea? They were sponsored by Shimano! The Durham
traditional elliptical would have done a pretty good job of this anyway. Although RD is not aware of
this "selling point" AFAIK, users would surely have noticed! (unless of course even the real cost of
pedalling counts for nothing) My guess is the researchers are now a tad embarrased by their paper.
But then even the very best minds make non-trivial mistakes - Newton, Einstein, Erdos...

Il n'y a que des imbeciles qui ne changent pas d'avis!

Andrew Bradley

 

[Andrew Bradley]

Phil Holman <[email protected]> wrote in message
news:[email protected]...
> >
> Just to keep the thread going, take a look at what was done in this study.........
> http://tinyurl.com/24sph
>

This study confirms what i mentioned earlier - Frank's calculation doesn't set a precedent.
Although he doesn't seem to realise it plenty of researchers have gone through the "internal work"
calculation, choosing to define "internal work" as the variation in mechanical energy no matter
what real life energy loss mechanisms (such as viscosity and soft tissue oscillation) are or are
not present.

I mean, do you understand what they call "mechanical efficiency" in the study you cite
(http://tinyurl.com/24sph)? All the costs of pedalling are already accounted for in the gross
efficiency value. Why did they feel justified in adding in "internal work" to derive another
"efficiency" figure? Surely if "internal work" were a meaningful measure of cost (it isn't) it
will already have been accounted for. IOW, they make higher cadences sound more efficient via a
fudge, no?

As the later (1997) study i mentioned says: "the internal work method is theoretically flawed".
(However, even as late as 2001, a study cites "internal work" as a _possible_ factor in the cost of
pedalling (separate from viscosity etc) but notes that the concept of internal work is
"controversial in cycling".)

So what do you think of the paper, Phil?

Andrew Bradley

 

[Phil Holman]

"Andrew Bradley" <[email protected]> wrote in message
news:8DOYb.7687$Y%

>But then even the very best minds make non-trivial mistakes - Newton, Einstein, Erdos...

Classical physics is a good heuristic as long are things are not too small, too fast, too light or
subject to Fermi exclusion. Look up, Heisenberg, Einstein, superfluid helium and baryonic matter.

Phil Holman

 

[Phil Holman]

"Andrew Bradley" <[email protected]> wrote in message
news:9DOYb.7688$Y%[email protected]...
> Phil Holman <[email protected]> wrote in message
> news:[email protected]...
> > >
> > Just to keep the thread going, take a look at what was done in this study.........
> > http://tinyurl.com/24sph
> >
>
> This study confirms what i mentioned earlier - Frank's calculation
doesn't
> set a precedent. Although he doesn't seem to realise it plenty of researchers have gone through
> the "internal work" calculation, choosing to define "internal work" as the variation in mechanical
> energy no matter what real life energy
loss
> mechanisms (such as viscosity and soft tissue oscillation) are or are
not
> present.
>
> I mean, do you understand what they call "mechanical efficiency" in
the
> study you cite (http://tinyurl.com/24sph)? All the costs of pedalling are already accounted for in
> the gross
efficiency
> value. Why did they feel justified in adding in "internal work" to derive another "efficiency"
> figure? Surely if "internal work" were a meaningful measure of cost (it isn't) it will already
> have been accounted for. IOW, they make higher cadences sound more efficient via a fudge, no?
>
> As the later (1997) study i mentioned says: "the internal work method
is
> theoretically flawed". (However, even as late as 2001, a study cites "internal work" as a
> _possible_ factor in the cost of pedalling (separate from viscosity
etc)
> but notes that the concept of internal work is "controversial in
cycling".)
>
> So what do you think of the paper, Phil?

I guess my final comments were only implicit and didn't quite do it, so.......it's a piece of
doodoo. It's like knowing the answer to a math problem and then fudging the calculations to get
there.You know the rate of energy input and the useful power output to the pedals. KE and PE changes
net to zero over exactly one revolution at constant pedal speed. What's left are a number of buckets
to put all the remaining losses. Into one, viscoelastic is kind of a catch all as AC pointed out.
Into another, by subtracting the useful power output from all muscle activity, you have the energy
required to stabilize the system. How do you model this? Integrating all of the lower limb segment
inertia loads over one pedal revolution and balancing these with forces from the appropriate
muscles, ligaments etc? How do you assign energy spent on lateral stability? Using athletes with
good muscle tone and low body fat will minimize soft tissue oscillations (no masters fatties). Whole
body losses over and above basic metabolic rate need to be accounted (heart, lungs etc). Somewhere
in here the inefficiency of converting chemical into mechanical energy has to be factored. Did I
miss anything? If you hire someone to model this setup, expect it to be late with significant budget
overrun. I can hear it now.....we're having a problem running the model but I think if we tweak it
just one more time (the umpteenth) we'll be done.

Phil Holman

 

[Frank Day]

"Andrew Bradley" <[email protected]> wrote in message news:<8DOYb.7687$Y%[email protected]>...
> Frank Day <[email protected]> wrote in message
> news:[email protected]...
>
> > > Just for the record, according to the calculations of the (eminent) researchers (peer-reviewed
> > > etc) pedal speed would be less than 2/3
> higher
> > > at TDC/BDC as compared to mid-stroke. This is for an average rider with normal pedals/cranks
> > > pedalling at 90RPM ("instantaneous cadence" varies between 70rpm and 115rpm) .
> >
> > If, in fact, such caculations have already been published in peer reviewed journals why on
> > earth is AC insisting the losses are "nada" or daring us to point to one article that
> > contradicts a single thing he has said? If you knew about this article, why on earth were you
> > agreeing with him?
>
> I have ranted that these calculations mean little long before this thread. I assume AC agrees with
> all right thinkers that , "the internal work method is theoretically flawed" . In view of his
> reaction to your ideas though , I'd say that he may need to knock a few heads in his own
> community, just to show he isn't biased

AC has shown himself to be so biased that it is not possible for me to consider him a "right
thinker" at this time. As with most physical systems there are more than one way to analyze the
system so I am not sure I understand why "the internal work method is theoretically flawed". Is this
because it comes up with a different result? Exactly what is the fatal flaw?
>
> Anyway, I told you about this paper from the word go and you agreed with me that pedalling cost
> could not be eliminated via a chainring. So who's side are you on?

I still doubt it could be eliminated although I agree it could be dramatically reduced to where it
might be considered for all pracitcal terms eliminated. However, by the same token, does this mean
that absent a severely eliptical chainring that dramaticaly changes pedal speed that you accept that
the pedaling motion results in substantial energy cost to the rider and this cost is cadence
dependent? After all, this is all I have been saying.
>
> > > I don't see why the UCI would ban what is only an elliptical chainring
> and I
> > > don't think they'd assume that the cost of pedalling had disappeared,
> would
> > > you?
> >
> > Perhaps not. Why don't you build one and market it. It should substantially increase power so
> > it should sell like hotcakes, assuming people can actually pedal in such a fashion and they
> > like it.
>
> Why did the researchers themselves not market the idea? They were sponsored by Shimano!

Why are you asking me?

> The Durham traditional elliptical would have done a pretty good job of this anyway.

I am unaware of this device. Perhaps.

> Although RD is not aware of this "selling point" AFAIK, users would surely have noticed! (unless
> of course even the real cost of pedalling counts for nothing)

The ral cost of pedaling counting for nothing is not in keeping with the data as I see it.
Apparently AC sees this cost as "nada".

> My guess is the researchers are now a tad embarrased by their paper. But then even the very best
> minds make non-trivial mistakes - Newton, Einstein, Erdos...

Which researchers? To which paper are you referring? Why should they be embarrassed? Not sure
I understand but, as it has been repeatedly postured during this thread, this shouldn't
surpise anyone.

Frank

 

[Tom Sherman]

Frank Day wrote:

> ... There is another thing the rider can do to minimize this loss that doesn't involve weights or
> varying pedal speed. That is to mount their cranks at 90 degrees to each other. In this
> configuration one thigh is accelerating when the other is decelerating so the energy could be
> transferred from one to the other through the BB. While these accelerations and decelerations are
> not perfectly timed, they are close enough that it should get these losses much smaller.
> Unfortunately, in order to do this one must be able to actually pedal in a complete circle because
> one can't help the other leg over the top by pushing down as at some point both feet are coming up
> at the same time. While this does require some external energy to increase the potential energy of
> the legs during this portion of the stroke it is all recovered on the down stroke so doesn't
> require any net energy....

So why should I pay a lot of money for PowerCranks when I can pull one crank and reinstall it 90-
degrees out of phase [1] for no cost other than my time (since I already own a crank puller)?

[1] I would probably do this on my trike, as it would eliminate balance issues when starting out.

Tom Sherman - Quad Cities

 

[Andrew Bradley]

"Phil Holman" <[email protected]> wrote in message news:<[email protected]>...
> "Andrew Bradley" <[email protected]> wrote in message news:8DOYb.7687$Y%
>
> >But then even the very best minds make non-trivial mistakes - Newton, Einstein, Erdos...
>
> Classical physics is a good heuristic as long are things are not too small, too fast, too light or
> subject to Fermi exclusion. Look up, Heisenberg, Einstein, superfluid helium and baryonic matter.
>
Heck no, I wasn't refering to that kind of stuff. Apparently Hooke corrected a schoolboy error by
Newton and Newton never forgave him, sabotaging his career. Erdos is reported to have got that 3-
door game show problem wrong. Einstein, well he did waste a good bit of time because he firmly
beleived quantum physics was a dead end...

Andrew Bradley