Powercranks

Frank Day wrote in message
...

You require internal resistance to magically modulate in order to
prevent it
which is far less plausible.

I require energy loss which can come from eccentric muscle
contraction. I find nothing implausible about that.

The point is that is has to _match_ the energy variation you calculate.

In fact, it seems
most plausible to me compared to the loss going completely to work
propelling the bicycle. How on earth does the body learn to do this?

Nobody said all the energy variation got to the rear wheel. Nobody has said
there is no excentric contraction. We can all identify a loss mechanism or
two, it's a question of _quantifying_ them. That's what your calculation is
supposed to do and there is no reason to suppose it comes close.


So, how do you account for the kinetic
energy variations.

I don't see anything to account for in them.

It is handled through eccentric muscle contraction.
There is more than one way to deal with this energy variation. How do
you know your way is correct?

Basic physics can explain your energy variations without the need for
losses. You want us to believe that internal losses will automatically
make
themselves equal to the energy variation, or (more recently) just the
loss
to excentric muscle work That sounds like magic to me.
Also, remember that excentric work is not just non-conservative, there
is an
extra cost, but you don't know what that is. Also bear in mind that
theres a
lot more power going to the pedals than that acounted for by the leg
energy
variations and that is likely to affect excentric muscle work of itself.
Just what does your calculation predict or demonstrate? We don't even
have
any numbers from you.

No, perhaps some of the energy variation gets transmitted to the
pedals, but all that isn't will vary with the square of the cadence.

You are clutching at straws now.

This is not an all or nothing proposition.

We need to know where, between all or nothing, it is.

You cannot have a closed, resistance free system with no chain and
constant
pedal speed.
Drop the constant pedal speed constraint and you can have a closed
system
with no resistances.

Sure I can, the forces the rider applies to the pedals must simply
vary to maintain a constant pedal speed. It would be harder to do at
higher cadences but it is not impossible.

The muscles would have to work excentrically , ie provide internal
resistance.

Because the muscles themseleves have to constrain the motion,
pedalling in the air is likely to be rather more wasteful than
pedalling with cranks, but this is beside the point.

No it isn't, it is the point. pedaling without pedals may be more
wasteful than pedaling with pedals but there is no proof (or, even,
evidence) that pedaling with pedals is suddenly transformed to be
perfectly efficient.

Another misrepresentation of what this thread has been about.

Aren't you claiming that all the energy variation gets transmitted to
the pedals so there are no losses and pedaling is energy conservative?

NO, I am not!

If I misunderstand your view, please state it again.

Muscle work is required to increase the mechanical energy. The mechanical
energy decrease which follows is used to overcome internal resistance and
drive the bike forward - just like muscle work is doing simultaneously..

No, assume no internal resistance. Where is the evidence that ANY
energy is tranferred in this fashion?

Elementary mechanics is all that is required.
Hold on though... have you got a resistance mechanism or not in your
model?
Is a resistance required or not?

No internal resistance required, only an application of positive and
negative energy causing the energy variations. In a fashion I suppose
this could be considered an "internal resistance".

"Negative energy" i'll take to indicate the prescence of internal resitance,
if you don't mind.


This is all supposition.

Like Newtons laws.

Where in Newton's laws does it say that humans are capable of doing
what is "optimal" when pedaling?

It doesn't

That is all I am saying.
Even though
it is theoretically possible doesn't mean it necessarily is happening
that way. To assume otherwise is is pure supposition.

Nobody mentioned optimal pedalling in connection with this..

There is no causal relationship established between leg energy loss
and any internal loss mechanism. There's no reason to assume it
represents excentric muscle work.

yes there is. It is how we learned how to pedal as children. Watch a
child learn to ride.
They can't do it until they learn how to control
the eccentric forces to keep the foot "attached" to the pedal.
What is
really the case is there is no reason to assume that as soon as one
reaches a certain age or seriousness about cycling that they suddenly
change the way they pedal.

Are you saying that pressure on the downward pedal (and thus energy
transfer) is not allowed between mid-stroke and BDC because a foot
would
slip off? This is when leg energy decreases and "payback" would occur.
If that is the case then how is the "down" leg to give the "up" leg
that
easy ride you seek to eliminate with your cranks?
This phenomenon would be a surprise to people whith force plate pedals
and
indeed anybody that rides a bike.

No, the problem is at the top and bottom of the arc where the energy
transfer of the decelerating thigh, in order to transfer this energy
will need to accelerate the foot forward.

By the top and bottom of the arc energy transfer is virtually complete.
And accelerating the foot forward near the top or backward near the bottom
would represent excentric contraction of which muscles?

You really do have your work cut out to match these things to the energy
variation. In fact in these sectors the pedals would probably be harder for
the foot to follow with the elliptical ring that eliminates the energy
variation altogether!


As i said, with a heavy chainset and a slightly elliptical ring,
internal work will be zero - but would any excentric muscle work
cease?

I don't understand. if eccentric muscle work doesn't cease then it
seems to me internal work cannot be zero.

Precisely! "Internal work" is a definition - total absolute mechanical
energy variation. As such the term is misleading.
Internal work can be eliminated via a chainring but internal _loss_,
which
is what we are actually interested in,
will continue. Do your childish pedallers suddenly learn to pedal like
grown ups when the mechanical energy variations disappear - even though
they
are still pedalling in circles?

I didn't realize that grown-ups pedaled substantially different than
children, of the 12-14 year old variety anyhow. I am not sure by what
you mean "when the mechanical energy variations disappear". I don't
know how to make them disappear on an ordinary bicycle. Do you?

Yes I do and i must have told you 10 times already, so I'll make this the
last time - you fit an elliptical ring.

I am glad to see you now realise the need to link internal work to a
specific loss, though.

All losses have a specific mechanism. It is not necessary to know what
the mechanism is to know that it is present.

Conservation of energy shows there are no "losses looking for a
mechanism"
implicit in your calculations so you'll have to get a loss mechanism
that
corresponds to it.
But i repeat myself...

There are "no losses looking for a mechanism" only if your assumptions
as to the completeness of kinetic energy transfer is correct. There is
no evidence it is.

Your energy variation calculation applies equally well to a totally loss
free system, therefore for it to describe loss you need to pinpoint the
magic resistance mechanism within a real pair of legs that will dissipate
the amount of energy you predict and ONLY that amount (to within reasonble
tolerance).
(Hint: give up on it, nobody else has succeeded)

Andrew Bradley

Terry Morse wrote in message ...
Frank Day wrote:

If viscous drag force "can" be a function of v^2 why doesn't rolling
resistance vary with V^2? I guess under some circumstances viscous
drag can vary with V^2

For most flow with gases, and liquids at high velocity, drag is
proportional to V^^2. For high viscosity (or very low Reynolds
number) flow in a fluid, drag varies with V.

Rolling resistance is viscoelastic and is not a high velocity fluid,
thus it varies with V.

As, me thinks, is the internal viscous resistance of muscle and joint movements.

Frank

"Andrew Bradley" wrote in message ...
Frank Day wrote in message
...

You require internal resistance to magically modulate in order to
prevent it
which is far less plausible.

I require energy loss which can come from eccentric muscle
contraction. I find nothing implausible about that.

The point is that is has to _match_ the energy variation you calculate.

I don't see the difficulty. If I know what the losses are I can devise
a scheme of eccentric muscle contraction to account for it.


In fact, it seems
most plausible to me compared to the loss going completely to work
propelling the bicycle. How on earth does the body learn to do this?

Nobody said all the energy variation got to the rear wheel. Nobody has said
there is no excentric contraction. We can all identify a loss mechanism or
two, it's a question of _quantifying_ them. That's what your calculation is
supposed to do and there is no reason to suppose it comes close.

Wait a minute. First I am told that the energy variation in the legs
is not lost in the legs because it is transmitted to the pedals. Now
you are telling me that this energy variation that is transmitted to
the pedals does not make it to the wheels? Uh, just where does it end
up?

"Nobody has said there is no eccentric contraction" They haven't? They
have said there is no energy lost from the pedaling motion. How can
there be eccentric contraction and no energy lost?

"That's what your calculation is supposed to do and there is no reason
to suppose it comes close" No reason to you perhaps but my calculation
is the only one I have seen "energy loss" varies as the experimental
energy loss, that is with the square of the cadence. That seems closer
than anyone else has come. I have asked and asked for someone to give
another mechanism that credibly varies in such a fashion.



So, how do you account for the kinetic
energy variations.

I don't see anything to account for in them.

It is handled through eccentric muscle contraction.
There is more than one way to deal with this energy variation. How do
you know your way is correct?

Basic physics can explain your energy variations without the need for
losses. You want us to believe that internal losses will automatically
make
themselves equal to the energy variation, or (more recently) just the
loss
to excentric muscle work That sounds like magic to me.
Also, remember that excentric work is not just non-conservative, there
is an
extra cost, but you don't know what that is. Also bear in mind that
theres a
lot more power going to the pedals than that acounted for by the leg
energy
variations and that is likely to affect excentric muscle work of itself.
Just what does your calculation predict or demonstrate? We don't even
have
any numbers from you.

No, perhaps some of the energy variation gets transmitted to the
pedals, but all that isn't will vary with the square of the cadence.

You are clutching at straws now.

This is not an all or nothing proposition.

We need to know where, between all or nothing, it is.

No we don't. If the energy efficiency of cyclists varies between 16
and 26% it seems reasonable that most of this is accounted for by
differences in pedaling style and not differences in muscle
contraction efficiency, bearing or chain friction, or rolling
resistance. I suspect the 16% efficiency group are close to as
inefficient as is possible while the 26% efficiency group are the
highest level pros who have spent years trying to learn how to pedal
more efficiently. I have never seen anyone try to account for these
variations. I believe this discussion we have been having here could
account for a lot of it.


You cannot have a closed, resistance free system with no chain and
constant
pedal speed.
Drop the constant pedal speed constraint and you can have a closed
system
with no resistances.

Sure I can, the forces the rider applies to the pedals must simply
vary to maintain a constant pedal speed. It would be harder to do at
higher cadences but it is not impossible.

The muscles would have to work excentrically , ie provide internal
resistance.

That is correct.

Because the muscles themseleves have to constrain the motion,
pedalling in the air is likely to be rather more wasteful than
pedalling with cranks, but this is beside the point.

No it isn't, it is the point. pedaling without pedals may be more
wasteful than pedaling with pedals but there is no proof (or, even,
evidence) that pedaling with pedals is suddenly transformed to be
perfectly efficient.

Another misrepresentation of what this thread has been about.

Aren't you claiming that all the energy variation gets transmitted to
the pedals so there are no losses and pedaling is energy conservative?

NO, I am not!

If I misunderstand your view, please state it again.

Muscle work is required to increase the mechanical energy. The mechanical
energy decrease which follows is used to overcome internal resistance and
drive the bike forward - just like muscle work is doing simultaneously..

"The mechanical energy decrease which follows is used to overcome
internal resistance and drive the bike forward - just like muscle work
is doing simultaneously." That statement makes no sense to me. What on
earth are you talking about?


No, assume no internal resistance. Where is the evidence that ANY
energy is tranferred in this fashion?

Elementary mechanics is all that is required.
Hold on though... have you got a resistance mechanism or not in your
model?
Is a resistance required or not?

No internal resistance required, only an application of positive and
negative energy causing the energy variations. In a fashion I suppose
this could be considered an "internal resistance".

"Negative energy" i'll take to indicate the prescence of internal resitance,
if you don't mind.

OK


This is all supposition.

Like Newtons laws.

Where in Newton's laws does it say that humans are capable of doing
what is "optimal" when pedaling?

It doesn't

That is all I am saying.
Even though
it is theoretically possible doesn't mean it necessarily is happening
that way. To assume otherwise is is pure supposition.

Nobody mentioned optimal pedalling in connection with this..

People have "mentioned" that my thoughts on pedaling losses is all wet
because ALL of the kinetic energy variation in the legs in the
constant cadence system gets transmitted to the pedals such that
pedaling is conservative. Seems pretty close to optimal to me.

There is no causal relationship established between leg energy loss
and any internal loss mechanism. There's no reason to assume it
represents excentric muscle work.

yes there is. It is how we learned how to pedal as children. Watch a
child learn to ride.
They can't do it until they learn how to control
the eccentric forces to keep the foot "attached" to the pedal.
What is
really the case is there is no reason to assume that as soon as one
reaches a certain age or seriousness about cycling that they suddenly
change the way they pedal.

Are you saying that pressure on the downward pedal (and thus energy
transfer) is not allowed between mid-stroke and BDC because a foot
would
slip off? This is when leg energy decreases and "payback" would occur.
If that is the case then how is the "down" leg to give the "up" leg
that
easy ride you seek to eliminate with your cranks?
This phenomenon would be a surprise to people whith force plate pedals
and
indeed anybody that rides a bike.

No, the problem is at the top and bottom of the arc where the energy
transfer of the decelerating thigh, in order to transfer this energy
will need to accelerate the foot forward.

By the top and bottom of the arc energy transfer is virtually complete.
And accelerating the foot forward near the top or backward near the bottom
would represent excentric contraction of which muscles?

To maintain constant energy would require accelerating the foot
forward (remember that elliptical chain ring) so to keep the pedal
speed constant requires a force preventing that acceleration. It can
come from the pedal such that the force retards the foot and the
reactive force drives the bicycle or it can come from eccentric muscle
contraction. Acceleration of the foot forward requires acceleration of
the knee joint in extension if the thigh fixed. In general, if trying
to control knee extension or flexion speed the eccentric muscles are
the hamstrings and quadricepts.

You really do have your work cut out to match these things to the energy
variation. In fact in these sectors the pedals would probably be harder for
the foot to follow with the elliptical ring that eliminates the energy
variation altogether!

I don't know why it would be so hard as most of us have been doing it
for 20-40 years and we have developed a pretty good feel for it.



As i said, with a heavy chainset and a slightly elliptical ring,
internal work will be zero - but would any excentric muscle work
cease?

I don't understand. if eccentric muscle work doesn't cease then it
seems to me internal work cannot be zero.

Precisely! "Internal work" is a definition - total absolute mechanical
energy variation. As such the term is misleading.
Internal work can be eliminated via a chainring but internal _loss_,
which
is what we are actually interested in,
will continue. Do your childish pedallers suddenly learn to pedal like
grown ups when the mechanical energy variations disappear - even though
they
are still pedalling in circles?

I didn't realize that grown-ups pedaled substantially different than
children, of the 12-14 year old variety anyhow. I am not sure by what
you mean "when the mechanical energy variations disappear". I don't
know how to make them disappear on an ordinary bicycle. Do you?

Yes I do and i must have told you 10 times already, so I'll make this the
last time - you fit an elliptical ring.

Last time I looked an eliptical ring is not on an "ordinary" bicycle,
especially an elliptical ring that varies the instantaneous cadence
from between 70 and 115. That is what it takes isn't it, didn't you
say?

I am glad to see you now realise the need to link internal work to a
specific loss, though.

All losses have a specific mechanism. It is not necessary to know what
the mechanism is to know that it is present.

Conservation of energy shows there are no "losses looking for a
mechanism"
implicit in your calculations so you'll have to get a loss mechanism
that
corresponds to it.
But i repeat myself...

There are "no losses looking for a mechanism" only if your assumptions
as to the completeness of kinetic energy transfer is correct. There is
no evidence it is.

Your energy variation calculation applies equally well to a totally loss
free system, therefore for it to describe loss you need to pinpoint the
magic resistance mechanism within a real pair of legs that will dissipate
the amount of energy you predict and ONLY that amount (to within reasonble
tolerance).
(Hint: give up on it, nobody else has succeeded)
My goodness, what is the problem here. The "magic" resistance
mechanism is most probably the muscles of the legs (what else could it
be?). If they expend energy, to abosrb these kinetic energy variations
so one can pedal at a constant rate, then the energy is lost as heat.
When these muscle contract they require blood and increase cardiac
output. This is reflected in an increased HR. See Phil's little
experiment if you need evidence. Seems pretty straightforward to me.

"Frank Day" wrote in message
om...
"Phil Holman" wrote in message
link.net...
"Frank Day" wrote in message
om...
(Andrew Bradley) wrote in message
For a system to be "conservative" it should require no external
energy
input to continue. Your system requires continual energy output so
falls down then energy output is less than that required. I see
you are saying it is all used and converted into work, but I don't
see it as a conservative system. Is launching the space shuttle,
retreiving it, refueling it and getting ready to launch again a
"conservative system". According to you, yes.

The space shuttle or riding a bicycle operate with both conservative
and non-conservative forces. Your space shuttle example illustrates
your inability to make a distinction. It would be accurate to say
the work done against gravity and acceleration is 100% conserved
in the form of PE and KE, the work done against air resistance is
totally lost.
What I think you are saying is, KE or PE is not conserved due to air
resistance. This is incorrect.

I don't understand. When it is sitting on the launch pad waiting to
lift off the KE is zero but the PE is the total of the energy due to
gravity and the chemical energy in the tanks. It gains KE and PE
during lift off from the utilization of the chemical PE which it then
loses in friction when it reenters the atmosphere. such that when it
gets to the ground again, it has lost energy, which must be made up
from an outside source to be returned to its starting state. How is
this conservative like a pendulum? It may be but I don't see it.

Without air resistance or friction losses KE/PE transfer is 100%
conserved. There is no cost of converting one to the other in the
absence of non-conservative forces. Your model of the KE energy
loss in pedaling is missing a perfectly matching loss mechanism.



Let us assume that it is possible to transfer all the kinetic
energy to the bicycle. Where is the evidence that this
acutally occurs?

Don't need any. In the real world, the amount of kinetic energy
recuperated might be less than that gobbled up by internal
resistances. So what?

No, assume no internal resistance. Where is the evidence that ANY
energy is tranferred in this fashion? This is all supposition.
People have looked at this and said "it is possible, therefore it
happens". I say phooey. There is no evidence to support this and,
in fact, the evidence is against it unless there is another
adequateexplanation for pedaling power losses varying with the
cube of the cadence.


How many more times, viscous drag force can be a function of v^2
which will be a power loss varying with the cube of cadence. In any
event, not knowing what it is exactly doesn't disqualify one from
knowing what it isn't.

If viscous drag force "can" be a function of v^2 why doesn't rolling
resistance vary with V^2? I guess under some circumstances viscous
drag can vary with V^2 but I am under no awareness that this is
present to any great degree in the human body, rather I was under the
impression that most of the resistance to motion we are talking about
here behaves as a rubber band or spring. Even if some of these losses
were present, it doesn't go to the magnitude of these losses. It might
be possible that there are two different losses, each varying as a
function of v^2. Under this scenario, the relative magnitude of each
loss then would determine its significnce to the rider.

The key argument I am trying to make now is the problem of what the
rider must do to make pedaling conservative under your scenario.
Riders are not passive stick figures but biological systems with
conscious control over the movement of these various parts. Unless
relaxation and contraction occurs at the exact proper time in a
multitude of muscles it would not be possible for the rider to
"conserve" energy as proposed. Like I said, just because it might be
possible doesn't mean it occurs. In fact, I believe the best analysis
of all the data would say that this mechanism of energy management is
rarely, if ever, present.

What you are saying is muscle activity slows down the leg segments in
concert with their kinematic translation which makes sure very little
kinetic energy goes to the pedals. Back at you , such coordination of
muscle activity would be quite a trick especially when it would be so
much easier to let the constraints of a constant pedal speed do all this
naturally by absorbing the KE against the pedal resistance.

I still get the impression that this is an accounting problem. The KE of
the legs when transferred to the pedals being balanced against one of a
few losses...drive train friction, tire rolling resistance or
aerodynamic drag.

Phil Holman

Frank Day wrote in message
om...

I require energy loss which can come from eccentric muscle
contraction. I find nothing implausible about that.

The point is that is has to _match_ the energy variation you
calculate.

I don't see the difficulty. If I know what the losses are I can devise
a scheme of eccentric muscle contraction to account for it.

This is hopeless. After all this you still don't/wont understand what it is
you have calculated.
Enough of your circular reasoning!

Andrew Bradley

dvt wrote in message ...
n crowley wrote:
what percentage of overall power is
being produced by the leg between 6 and 12 o'clock.

100%.

By the way, noel, I saw this really cool movie that I think you should
see. I don't remember the name of the movie, who was in it, or any of
the details, but you should see it. You'd really like it.

Dave
dvt at psu dot edu





Don't let it get to you, it's not your fault that you do not understand, you
are in keeping with all other cyclists and their traditional coaches. The
answer should be, for a very small input of effort, it can increase
the overall pedal power by the total weight of working leg plus part weight of
idling leg. With the correct equipment that could be easily worked out. That
is how PC's give the advantage but because of the additional disadvantages when
using the PC's, that increase would be somewhat reduced from that of normal
cranks. This advantage also applies to the linear pedaling style of Anquetil
in addition to its many other super advantages. But don't forget, where today's
cycling is concerned, all these advantages are even more important as the
advantages offered by drugs are gradually removed from the scene.

"Phil Holman" wrote in message hlink.net...
"Frank Day" wrote in message
om...
"Phil Holman" wrote in message
link.net...
"Frank Day" wrote in message
om...
(Andrew Bradley) wrote in message
For a system to be "conservative" it should require no external
energy
input to continue. Your system requires continual energy output so
falls down then energy output is less than that required. I see
you are saying it is all used and converted into work, but I don't
see it as a conservative system. Is launching the space shuttle,
retreiving it, refueling it and getting ready to launch again a
"conservative system". According to you, yes.

The space shuttle or riding a bicycle operate with both conservative
and non-conservative forces. Your space shuttle example illustrates
your inability to make a distinction. It would be accurate to say
the work done against gravity and acceleration is 100% conserved
in the form of PE and KE, the work done against air resistance is
totally lost.
What I think you are saying is, KE or PE is not conserved due to air
resistance. This is incorrect.

I don't understand. When it is sitting on the launch pad waiting to
lift off the KE is zero but the PE is the total of the energy due to
gravity and the chemical energy in the tanks. It gains KE and PE
during lift off from the utilization of the chemical PE which it then
loses in friction when it reenters the atmosphere. such that when it
gets to the ground again, it has lost energy, which must be made up
from an outside source to be returned to its starting state. How is
this conservative like a pendulum? It may be but I don't see it.

Without air resistance or friction losses KE/PE transfer is 100%
conserved. There is no cost of converting one to the other in the
absence of non-conservative forces.

So, if my rocket were to take off from the moon, orbit the moon a
cople of times, then fire the rockets again to land, you are saying
this would be a conservative use of KE/PE? You are considering
chemicaal energy potential energy aren't you?

Your model of the KE energy
loss in pedaling is missing a perfectly matching loss mechanism.

Of course it has a perfectly matching loss mechanism. It is the
combination of eccentric muscle contraction and transfer of kinetic
energy to the pedals. It is impossible to know the magnitude of each
of these as it will vary depending upon the ability of the rider.


Let us assume that it is possible to transfer all the kinetic
energy to the bicycle. Where is the evidence that this
acutally occurs?

Don't need any. In the real world, the amount of kinetic energy
recuperated might be less than that gobbled up by internal
resistances. So what?

No, assume no internal resistance. Where is the evidence that ANY
energy is tranferred in this fashion? This is all supposition.
People have looked at this and said "it is possible, therefore it
happens". I say phooey. There is no evidence to support this and,
in fact, the evidence is against it unless there is another
adequateexplanation for pedaling power losses varying with the
cube of the cadence.


How many more times, viscous drag force can be a function of v^2
which will be a power loss varying with the cube of cadence. In any
event, not knowing what it is exactly doesn't disqualify one from
knowing what it isn't.

If viscous drag force "can" be a function of v^2 why doesn't rolling
resistance vary with V^2? I guess under some circumstances viscous
drag can vary with V^2 but I am under no awareness that this is
present to any great degree in the human body, rather I was under the
impression that most of the resistance to motion we are talking about
here behaves as a rubber band or spring. Even if some of these losses
were present, it doesn't go to the magnitude of these losses. It might
be possible that there are two different losses, each varying as a
function of v^2. Under this scenario, the relative magnitude of each
loss then would determine its significnce to the rider.

The key argument I am trying to make now is the problem of what the
rider must do to make pedaling conservative under your scenario.
Riders are not passive stick figures but biological systems with
conscious control over the movement of these various parts. Unless
relaxation and contraction occurs at the exact proper time in a
multitude of muscles it would not be possible for the rider to
"conserve" energy as proposed. Like I said, just because it might be
possible doesn't mean it occurs. In fact, I believe the best analysis
of all the data would say that this mechanism of energy management is
rarely, if ever, present.

What you are saying is muscle activity slows down the leg segments in
concert with their kinematic translation which makes sure very little
kinetic energy goes to the pedals. Back at you , such coordination of
muscle activity would be quite a trick especially when it would be so
much easier to let the constraints of a constant pedal speed do all this
naturally by absorbing the KE against the pedal resistance.

Yes, that is what I am saying and I don't believe it would be "quite a
trick". It is probably what comes "naturally". it is a very similar
coordination to running and it is the cycling coordination learned at
a very young age where foot speed and direction must be "properly"
controlled to maintain contact with the pedals. To me, it is a bigger
stretch that the rider can magically transform the muscles into flacid
bystanders in perfectly coordination with the kinetic energy transfer
needs to allow such transfer to occur.

As a result of this "discussion" I am coming to the conclusion that
differing riders have differing abilities to "allow" this energy
transfer which probably accounts for the varying energy effiiciencies
measured experiementally and could be one of the major reasons PC's
increase power in the cyclist.

I still get the impression that this is an accounting problem. The KE of
the legs when transferred to the pedals being balanced against one of a
few losses...drive train friction, tire rolling resistance or
aerodynamic drag.

The problem with your analysis is no one has actually shown that such
transfers actually occur. It should be "easy" to do. If the leg at
maximum kinetic energy has energy X and the leg at minimum kinetic
energy has energy Y it should be possible to look at the pedal forces
to see if the forces are there in the proper magnitude to account for
these energy transfers. (it might be a little difficult to account for
this perfectly as no one knows that the actual masses and distribution
of mass of the various components and so, while it is possible to know
the speeds and accelerations with certainty, it is not possible to
know the total kinetic energy in the legs with certainty.) This might
be easiest to do on the upstroke where pedal forces are generally
negative but one would expect to see positive forces if this energy
transfer actually occurred. I don't see how it can occur when pedal
forces are negative as regards powering the bicycle.

Frank

n crowley wrote:

dvt wrote in message ...

By the way, noel, I saw this really cool movie that I think you should
see. I don't remember the name of the movie, who was in it, or any of
the details, but you should see it. You'd really like it.

Don't let it get to you, it's not your fault that you do not understand, you
are in keeping with all other cyclists and their traditional coaches.

Oh, yeah, I forgot to mention. That movie has awesome special effects.
You really should see it. It will improve your life greatly. It might
even eliminate your lower back pain.

--
Dave
dvt at psu dot edu

As I read through this thread (although I won't claim to understand much of the physiology) I can't help but feel like the truth lies somewhere between the middle of the two extremes... Obviously a dramatic power increase will only be experienced by a non-trained cyclist through power cranks, but the other side the argument (adding additional muscles to do the pedaling adding no value since you can already operate at VO2 max) seems to be lacking as well based on my own personal (anecdotal) experiences...

The discussion of the hand crank cycle got me thinking about a fellow cyclist I see all the time where I train who only has one leg. Yesterday I managed to ask him several probing questions about his ability to ride before and after his accident (he lost his left leg in a motorcycle accident 5 years ago). I explained to him about the power cranks and how "pedaling in circles" seems to be controversial, and the basic arguments (as I understand them) against it doing anything for you. He told me that he is now capable of riding at the same exertion level and HR as he was with two legs but that his average speeds are about 5km/hr slower than before the accident (I didn't ask him how long it took to build endurance with only one leg). He rides more now than he did, and trains harder (300-400 km/week) and despite being 20 lbs (my guess, I don't know what a leg weighs) lighter he can't even maintain the same speed... now obviously n=1, and there isn't much to be concluded from this other than here is a guy that rides slower with one leg than he did with two several years ago, but my point is if he can max out his oxygen delivery system (sorry for verbiage, I'm an engineer not physiologist) with one leg and he is significantly slower, wouldn't this lend credibility to what Frank Days is trying to say regarding muscle recruitment? In 54 pages of discussion and bickering I saw no reference to one-legged cyclists so I thought I would bring it up just as a thought experiment. I mean if I understand the argument against powercranks doing anything, it should hold true that a well trained one-legged cyclist should be able to make the same amount of "sustainable" power that he/she could have with both legs, but with the one example I know of this isn't true. Thoughts???

Originally Posted by wilmar13

As I read through this thread (although I won't claim to understand much of the physiology) I can't help but feel like the truth lies somewhere between the middle of the two extremes... Obviously a dramatic power increase will only be experienced by a non-trained cyclist through power cranks, but the other side the argument (adding additional muscles to do the pedaling adding no value since you can already operate at VO2 max) seems to be lacking as well based on my own personal (anecdotal) experiences...

The discussion of the hand crank cycle got me thinking about a fellow cyclist I see all the time where I train who only has one leg. Yesterday I managed to ask him several probing questions about his ability to ride before and after his accident (he lost his left leg in a motorcycle accident 5 years ago). I explained to him about the power cranks and how "pedaling in circles" seems to be controversial, and the basic arguments (as I understand them) against it doing anything for you. He told me that he is now capable of riding at the same exertion level and HR as he was with two legs but that his average speeds are about 5km/hr slower than before the accident (I didn't ask him how long it took to build endurance with only one leg). He rides more now than he did, and trains harder (300-400 km/week) and despite being 20 lbs (my guess, I don't know what a leg weighs) lighter he can't even maintain the same speed... now obviously n=1, and there isn't much to be concluded from this other than here is a guy that rides slower with one leg than he did with two several years ago, but my point is if he can max out his oxygen delivery system (sorry for verbiage, I'm an engineer not physiologist) with one leg and he is significantly slower, wouldn't this lend credibility to what Frank Days is trying to say regarding muscle recruitment? In 54 pages of discussion and bickering I saw no reference to one-legged cyclists so I thought I would bring it up just as a thought experiment. I mean if I understand the argument against powercranks doing anything, it should hold true that a well trained one-legged cyclist should be able to make the same amount of "sustainable" power that he/she could have with both legs, but with the one example I know of this isn't true. Thoughts???

One question needs to be answered , what percentage of his pedal power is being applied by drawing back, pulling up and forcing pedal over the top. With only one leg he will be able to give power application in these areas his full attention which is something a normal rider using powercranks cannot do.