Is it true that the "round pedalling stroke" is a myth?



WillemJM

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I have never analyzed it in the detail covered here before, interesting thread. When riding at a young age, our coaches always told us it takes years to perfect pedaling style and to try and power through the whole circle. The way we practiced this, (and I still do) was to remove one foot from the pedal and pedaling with only one leg, training to eliminate the dead spots, then doing the same alternating to the other leg.

All I know, is that if I start struggling to stay in the pack, or on someone's wheel, I immediately concentrate on fluid pedaling and it often makes the difference between not getting dropped and hanging in there.

I don't quite follow the graph, if one clicks on the graph there are two. But both show almost zero, or no pull on the upstroke and it appears as if one group was just much stronger than the other.

I was also taught that the reason speed is at high candence while climbing is at a much lower cadence, is because with speed one has momentum, aiding in more equal torque distribution and enabling higher efficiency.
 

n crowley

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Originally Posted by alienator .


Yes you are. You're missing how the biomechanics of the human body, specifically the leg and its parts, work with the bicycle. You are not turning pedals with 3 link mechanical system powered by an independent power source whose output can be ramped up as needed. It's certainly not as easy as just applying the maximal force normal to the crank.

From ' Cycling Weekly ' magazine.


Taken as a whole, the leg and crank system has five pivots, hip, knee, ankle; bracket and pedal axle. If the ankle is fixed, the movement of the other four pivots is constrained, in other words there is only one possible range of motion. Allow the ankle to pivot, and anything is possible.
 

fergie

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Originally Posted by n crowley .



From ' Cycling Weekly ' magazine.


Taken as a whole, the leg and crank system has five pivots, hip, knee, ankle; bracket and pedal axle. If the ankle is fixed, the movement of the other four pivots is constrained, in other words there is only one possible range of motion. Allow the ankle to pivot, and anything is possible.
I believe Alex Simmons may have something to say about that having achieved higher power on the bike after having his lower leg amputated. Have observed similar with other lower leg amputees.

Real coaches don't get their information from general books and cycling mags.
 

daveryanwyoming

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Originally Posted by n crowley .



From ' Cycling Weekly ' magazine.


Taken as a whole, the leg and crank system has five pivots, hip, knee, ankle; bracket and pedal axle. If the ankle is fixed, the movement of the other four pivots is constrained, in other words there is only one possible range of motion. Allow the ankle to pivot, and anything is possible.
Do you realize you've posted nothing to dispute the main point of Alienator's previous post? Here's the pertinent part bolded:

Originally Posted by alienator


Yes you are. You're missing how the biomechanics of the human body, specifically the leg and its parts, work with the bicycle. You are not turning pedals with 3 link mechanical system powered by an independent power source whose output can be ramped up as needed. It's certainly not as easy as just applying the maximal force normal to the crank.
The question is not whether it's a simple 3 link mechanical system or a 5 pivot system with additional degrees of freedom. The key point is that the power source to that system has physiological limits not described by simple mechanical linkage models. To date measured attempts to alter natural pedaling and to apply pedaling forces over larger or different portions of the pedal stroke have come up short based on physiological limits, not mechanical limits.

You make a basic assumption that the leg muscles can generate and sustain additional power if the pattern of force application is altered from what cyclists do naturally. That basic assumption is not backed by empirical evidence. Again, by offering a very unconventional theory on how cyclists should pedal the burden of proof is on you to demonstrate the superiority of your ideas.

Demonstrate repeatable results and you might convince someone. Continue to layer your ideas on unfounded basic assumptions such as riders being able to sustain more power by altering the way that power is applied to the cranks and folks will continue to ignore your ideas.

-Dave
 

maydog

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How are we defining efficiency here?

Oversimplifying I see the efficiency equation being mechanical energy out / metabolic energy in. Forces non tangential to the axis of crank rotation do no work and therefore do not affect efficiency (assuming the metabolic costs of producing such forces is low). A bad stroke may impact maximal power output, I think.

Also consider that it is impossible to generate maximum torque throughout the pedal stroke. Extended muscles produce less force. At the top of the stroke, both the quadriceps and glutes are fairly extended. More force can be produced as the muscles shorten:

http://en.wikipedia.org/wiki/Muscle_contraction#Force-length_and_force-velocity_relationships

My personal thought on the matter is that a good, round pedal stroke gets the unloaded, trailing leg out of the way. The trailing leg can produce tangential forces in the opposite direction. Mentally (but not actually generating significant force) "scraping mud and or pulling up" improves efficiency because the trailing leg can rob power that could be going to the rear wheel by requiring the leading leg to push it up and over. Also at the bottom of the stroke, the leg may have a tendency to stay contracted too long requiring the leading leg to fight it.
 

alienator

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WillemJM said:
I was also taught that the reason speed is at high candence while climbing is at a much lower cadence, is because with speed one has momentum, aiding in more equal torque distribution and enabling higher efficiency.
The problem with that is that legs and feet aren't build to maintain angular momentum. You have to put in energy to maintain that momentum. As for the crank set itself, it's moment of inertia is not large at all.
 

alienator

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n crowley said:
 From ' Cycling Weekly ' magazine.  Taken as a whole, the leg and crank system has five pivots, hip, knee, ankle; bracket and pedal axle. If the ankle is fixed, the movement of the other four pivots is constrained, in other words there is only one possible range of motion. Allow the ankle to pivot, and anything is possible.
Actually it's not, and if you did a simple sketch you'd see why. No matter, there is nothing linear about your linear pedaling method. More importantly you're just simply repeating your claims over and over without any substantiating proof (data, studies,......)
 

n crowley

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Originally Posted by fergie .

I believe Alex Simmons may have something to say about that having achieved higher power on the bike after having his lower leg amputated. Have observed similar with other lower leg amputees.

Once again you've got it assways, Alex demonstrates that natural pedallers don't make use of their ankles when pedalling, that is why without his ankle he is even more powerful than before his accident. As the magazine stated, allow the ankle to pivot and anything is possible.
 

n crowley

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Originally Posted by daveryanwyoming .

:

To date measured attempts to alter natural pedaling and to apply pedaling forces over larger or different portions of the pedal stroke have come up short based on physiological limits, not mechanical limits.



-Dave

Is it possible for you to give an example of one of these attempts.
 

daveryanwyoming

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Originally Posted by n crowley .



Is it possible for you to give an example of one of these attempts.
Sure, here's one: http://www.ncbi.nlm.nih.gov/pubmed/17545890


Here's a chart from a similar study that was posted in this thread a few pages ago:

The solid lines for both the Elite-cyclist and Non-cyclist groups represent force application for both the case of platform and clipless pedals and show that whether trained or not riders tend to apply force in very nearly the same way whether or not their feet are attached to the pedals. But when coached to alter their force application both groups changed to the dotted curves which showed altered force application but lower peak torque and lower power and if you read the full study, lower GME for both rider groups.

Now I realize this is NOT the altered pedaling style that you are advocating but it goes directly the point that attempts to alter force application while pedaling have historically come up short. Repeat this study using your pedaling methods, demonstrate that power does not drop but actually increases and you may convince some folks. Or if you don't like the rigorous lab approach, then demonstrate your theories via on the road results, either win some races or convince some talented rider to try your methods and win some races (after all Lemond didn't invent the aero bar he just took the risk to try it in one of the biggest races of his life) and then you may be taken seriously.

-Dave
 

WillemJM

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Originally Posted by daveryanwyoming .


Sure, here's one: http://www.ncbi.nlm.nih.gov/pubmed/17545890


Here's a chart from a similar study that was posted in this thread a few pages ago:

The solid lines for both the Elite-cyclist and Non-cyclist groups represent force application for both the case of platform and clipless pedals and show that whether trained or not riders tend to apply force in very nearly the same way whether or not their feet are attached to the pedals. But when coached to alter their force application both groups changed to the dotted curves which showed altered force application but lower peak torque and lower power and if you read the full study, lower GME for both rider groups.

Now I realize this is NOT the altered pedaling style that you are advocating but it goes directly the point that attempts to alter force application while pedaling have historically come up short. Repeat this study using your pedaling methods, demonstrate that power does not drop but actually increases and you may convince some folks. Or if you don't like the rigorous lab approach, then demonstrate your theories via on the road results, either win some races or convince some talented rider to try your methods and win some races (after all Lemond didn't invent the aero bar he just took the risk to try it in one of the biggest races of his life) and then you may be taken seriously.

-Dave
Trying to understand the graphs?
Are platform and clipless pedals those where your feet are not attached to the pedals and what is meant by clipless feedback? Can't make sense of that?
Is that suggesting that one could put out the same power without attaching feet to the pedals?
 

frost

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Oct 25, 2007
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Originally Posted by maydog .

How are we defining efficiency here?

Oversimplifying I see the efficiency equation being mechanical energy out / metabolic energy in. Forces non tangential to the axis of crank rotation do no work and therefore do not affect efficiency (assuming the metabolic costs of producing such forces is low). A bad stroke may impact maximal power output, I think.

Also consider that it is impossible to generate maximum torque throughout the pedal stroke. Extended muscles produce less force. At the top of the stroke, both the quadriceps and glutes are fairly extended. More force can be produced as the muscles shorten:

http://en.wikipedia.org/wiki/Muscle_contraction#Force-length_and_force-velocity_relationships

My personal thought on the matter is that a good, round pedal stroke gets the unloaded, trailing leg out of the way. The trailing leg can produce tangential forces in the opposite direction. Mentally "pulling up" improves efficiency because the trailing leg can rob power that could be going to the rear wheel by requiring the leading leg to push it up and over. Also at the bottom of the stroke, the leg may have a tendency to stay contracted too long requiring the leading leg to fight it.
Your definition of efficiency is not oversimplification but exactly how it is defined. And you don't have to guess or speculate because the effects of altering pedaling have been studied measuring exactly that mechanical energy out / metabolic energy in with end result described by Dave above.
 

daveryanwyoming

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Originally Posted by WillemJM .

Trying to understand the graphs?
Are platform and clipless pedals those where your feet are not attached to the pedals and what is meant by clipless feedback? Can't make sense of that?
Is that suggesting that one could put out the same power without attaching feet to the pedals?
Platform pedals are pedals with no attachments to the shoe and no toe clips to secure the foot. IOW, pretty much the pedals most of us rode with as kids and some MTB riders and most BMX riders still use.

Clipless pedals are what most road cyclists and many if not most MTB riders use where there's a cleat on the sole of the shoe and a step in pedal system that can be released with the twist of the foot. It's only 'clipless' when compared to conventional toe clips and straps but definitely secures the foot. It's likely what you use on your road bike.

'Clipless feedback' is a phrase the researchers used to describe the test that riders performed while the researchers 'coached' them and advised them to change the way they were pedaling. IOW, it was coached pedaling attempting to get the riders to perform in a specific way as opposed to the rider's natural pedaling style. In the case of the Mornieux chart the riders were coached to pull up on the back of the pedal stroke which from the charts it's clear they did to some extent but at the expense of downstroke torque and at the expense of both overall power during the pedal stroke and at the expense of Gross Metabolic Efficiency which means they consumed higher rates of oxygen and burned through additional fuels for less power at the pedal. IOW, they worked harder for less power produced which is a lousy tradeoff.

And yes, these studies demonstrate that at least for steady state riding you do not gain any power by having your feet attached to the pedals. Now whether that's true in sprints or other dynamic situations isn't clear from this data though top level BMX racers seem to do just fine and they have some incredible sprint power. But that doesn't mean clipless pedals and secure attachment is a bad thing, I feel much safer and can do things like bunny hop road obstacles or stay connected to my bike better in rough terrain or full out of the saddle sprints with solid pedal connections. But what these studies do show is that we don't really pull up on our pedals regardless of the pedals we use and we don't really lose power if we're not securely connected to the pedals.

BTW, that pretty much takes us back to the first few pages of this thread that's gone way off the tracks.

-Dave
 

n crowley

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Originally Posted by daveryanwyoming .


Sure, here's one: http://www.ncbi.nlm.nih.gov/pubmed/17545890


Here's a chart from a similar study that was posted in this thread a few pages ago:

The solid lines for both the Elite-cyclist and Non-cyclist groups represent force application for both the case of platform and clipless pedals and show that whether trained or not riders tend to apply force in very nearly the same way whether or not their feet are attached to the pedals. But when coached to alter their force application both groups changed to the dotted curves which showed altered force application but lower peak torque and lower power and if you read the full study, lower GME for both rider groups.

Now I realize this is NOT the altered pedaling style that you are advocating but it goes directly the point that attempts to alter force application while pedaling have historically come up short. Repeat this study using your pedaling methods, demonstrate that power does not drop but actually increases and you may convince some folks. Or if you don't like the rigorous lab approach, then demonstrate your theories via on the road results, either win some races or convince some talented rider to try your methods and win some races (after all Lemond didn't invent the aero bar he just took the risk to try it in one of the biggest races of his life) and then you may be taken seriously.

-Dave

Thanks, but nothing new there, like I said, all research is confined to variations of the same basic pedalling style and a waste of research time. Nobody has attempted to tackle the dead spot sector. I hope BrimBros can supply the non sinusoidal graph that will verify my claims.
 

frost

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Originally Posted by n crowley .



Thanks, but nothing new there, like I said, all research is confined to variations of the same basic pedalling style and a waste of research time. Nobody has attempted to tackle the dead spot sector. I hope BrimBros can supply the non sinusoidal graph that will verify my claims.
So why wait for BrimBros? There are much more accurate equipment available in lab environment. Or if you don't like that why not take the opportunity to prove yourself in a race as has been suggested?
 

daveryanwyoming

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Originally Posted by n crowley .
... I hope BrimBros can supply the non sinusoidal graph that will verify my claims.
Well two problems with that...

- First you may be waiting a long time for Brim Brothers to produce a commercial power measuring pedal as they've been beset by many setbacks and I wouldn't hold my breath waiting for their commercial product release. So is there a reason other commercially available methods such as the Look power pedals that are available today will not work?

- Secondly just having commercial access to the ideal measurement pedal won't be enough. You're still going to have to convince some riders to adopt your pedaling style and to do the tests. That won't happen automatically just because Brim Brothers finally gets to the market with their products. If you're going to recruit test subjects why not do it now and demonstrate that your methods produce more power as that's a necessary condition for proving your thesis. If they do indeed produce more power then you can take the next step of proving that the power came from specific application of force and your pedaling theories but if you can't sustain higher power then the second bit really doesn't matter.

The burden of proof remains on you, not Brim Brothers, not others to disprove your theories but on the person advocating unconventional methods. That's the price of a paradigm change...aint it a *****?

-Dave
 

alienator

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n crowley said:
  Thanks, but nothing new there, like I said, all research is confined to variations of the same basic pedalling style and a waste of research time. Nobody has attempted to tackle the dead spot sector. I hope BrimBros can supply the non sinusoidal graph that will verify my claims.
Research that provides useable data isn't a waste of time. Further repeating research others have done, if that's the case here--is an important function of research and a result of the scientific method. Such experiments are needed to confirm an hypothesis or to reject an hypothesis. You missed one critical point: the clipless feedback test showed a reduction in the average force applied. While that may not be the result for every type of cadence imaginable, it does say that it is definitely not a given that trying to improve the force applied in weak parts of the pedal cycle will improve the average force applied. That's a pretty pertinent negative. As for Brim Brothers, why would they provide the graph you want? BTW, the graph of your pedaling style will be some sinusoid, too.