For the "pedaling technique doesn't matter crowd"

[Alex Simmons/RST]

Here it is - although looking at what I can find, I can't verify if data was from from road rider or trainer simulations (there is reference to "simulated" gear which suggests trainer). In any case, it's still interesting.

From April 2011:

Well it just so happens that Eric Lin serendipitously posted some data on the wattage forum to show the difference in micro accelerations/speed during pedaling on flat v steep climb.

As per Eric's post:

Y-axes are speed in meters per second.

Cadence was 70-80 rpm for the
2nd graph in a simulated 39x27 gear and 270-300W.

It demonstrates that the variance between each scenario (in terms of changes of speed during each pedal stroke) is pretty small.

i.e. there isn't a large difference between the amplitudes of speed plots, ~0.03 - 0.04m/s in 0% grade scenario vs ~ 0.035 - 0.045 m/s in the low cadence 10% grade scenario.

 

[FrankDay]

2nd graph in a simulated 39x27 gear and 270-300W.

My guess this is from a trainer ride or an exercise bike, either way a bike with small "momentum" compared to riding on the road and still these changes in pedal speed are tiny. Without these variations tools like spinscan could not work but that doesn't make them important to a rider going fast or slow.

 

[JayKosta]

My guess this is from a trainer ride or an exercise bike, either way a bike with small "momentum" compared to riding on the road and still these changes in pedal speed are tiny. Without these variations tools like spinscan could not work but that doesn't make them important to a rider going fast or slow.

====================================
Frank,

I don't understand why you think the variations in crank speed through a rotation are unimportant.

If the crank speed was constant through the full rotation, then the torque would also be constant.

I think that the torque decreases at certain crank positions mainly because the crank speed slows at those locations. Basically the foot/feet doesn't (or can't) maintain enough circular speed to keep a constant torque.

Jay Kosta
Endwell NY USA

 

[FrankDay]

====================================
Frank,

I don't understand why you think the variations in crank speed through a rotation are unimportant.

If the crank speed was constant through the full rotation, then the torque would also be constant.

I think that the torque decreases at certain crank positions mainly because the crank speed slows at those locations. Basically the foot/feet doesn't (or can't) maintain enough circular speed to keep a constant torque.

Jay Kosta
Endwell NY USA

Huh? There is always some positive torque on the two crank arm system on bicycles with a free wheel because, if there weren't, the cranks would come to a quick stop (the cranks would go "forever" but the attached legs are always accelerating or decelerating in a more linear fashion which requires substantial energy). So, variation in crank speed simply is a result of newtons laws. F=ma. When crank forces are small wind and rolling resitance slows the bike and crank speed and when they are large bike and crank speed increases. At cadences of 90 or so these changes are so small (because of the relatively huge mass of the rider) that variations are miniscule. The question is whether these variations can affect power output. I submit they are so small, whether one is using a non-circular ring or anything else that they have no affect on power production.

edit: and a slower pedal speed makes it easier to apply torque to the crank (not harder) because it is not necessary to get the foot up to a higher pedal speed before force is applied.

 

[Alex Simmons/RST]

If the crank speed was constant through the full rotation, then the torque would also be constant.

Ummm, no.
...

 

[JayKosta]

Frank and Alex,

I'm still confused about the 'crank speed variation' and 'torque variation' relationship.

I DO agree that for actual 'on road/track' cycling the torque can vary without affecting the bike's speed due to things such as wind, surface inclination, etc.
But what about for a theoretical 'steady-state resistance' situation (or perhaps a stationary trainer) where the resistance is constant?

In the steady-state situation, I think that constant crank speed and constant total crank spindle torque is needed to give constant wheel speed.
Yes, the torque varies between left and right crank arms, but the spindle speed and torque needs to be constant to give constant wheel speed, when the resistance is constant.

In steady-state resistance, how could a change in crank speed NOT result in a change in wheel speed?

Thanks,
Jay Kosta
Endwell NY USA

 

[FrankDay]

Frank and Alex,

I'm still confused about the 'crank speed variation' and 'torque variation' relationship.

I DO agree that for actual 'on road/track' cycling the torque can vary without affecting the bike's speed due to things such as wind, surface inclination, etc.
But what about for a theoretical 'steady-state resistance' situation (or perhaps a stationary trainer) where the resistance is constant?

In the steady-state situation, I think that constant crank speed and constant total crank spindle torque is needed to give constant wheel speed.
Yes, the torque varies between left and right crank arms, but the spindle speed and torque needs to be constant to give constant wheel speed, when the resistance is constant.

In steady-state resistance, how could a change in crank speed NOT result in a change in wheel speed?

Thanks,
Jay Kosta
Endwell NY USA

You are correct. If all the variables are held constant then in a steady state situation a constant pedal torque would result in a constant pedal/wheel speed. This would be the situation if an electric motor were driving the bicycle. But, it simply cannot happen in the real world with humans powering the bicycle.

 

[Alex Simmons/RST]

Frank and Alex,

I'm still confused about the 'crank speed variation' and 'torque variation' relationship.

I DO agree that for actual 'on road/track' cycling the torque can vary without affecting the bike's speed due to things such as wind, surface inclination, etc.
But what about for a theoretical 'steady-state resistance' situation (or perhaps a stationary trainer) where the resistance is constant?

In the steady-state situation, I think that constant crank speed and constant total crank spindle torque is needed to give constant wheel speed.
Yes, the torque varies between left and right crank arms, but the spindle speed and torque needs to be constant to give constant wheel speed, when the resistance is constant.

In steady-state resistance, how could a change in crank speed NOT result in a change in wheel speed?

Thanks,
Jay Kosta
Endwell NY USA

Refer to those charts I put up earlier - they show the measured variation in instantaneous crank speed per revolution on a trainer in a steady state scenario. In the first one, at 250W and 90rpm, the variance from highest to lowest instantaneous crank speed during a crank revolution is about 0.5%.

We already know that the instantaneous torque being applied will be in a roughly sinusoidal pattern from near zero newtons-metres to a peak twice per revolution. At 250W and 90rpm, that peak will be approx 50Nm.

The reason the crank doesn't vary speed much during the two torque minimums each pedal stroke is the stored kinetic energy in the system is sufficient to prevent the speed dropping much during those fractions of a second even though there is a variety of resistance forces still acting against the wheel.

On the road and track, the stored KE of the bike/rider is pretty high.

Simple example to demonstrate - when riding along the flat on good road and you completely stop pedalling, you don't suddenly stop moving forward. You slow down quite gradually. Same on an indoor trainer - the wheel doesn't stop the instant you stop pedalling - it continues to roll, slowing down, usually faster than it would on the road because the stored KE is less but it's still enough that the variation in crank speed during a pedal stroke is pretty small.

 

[coapman]

Remember, there are 360º to the pedaling circle and the pedal is rising during 180º of that circle. Once the pedal is beyond BDC it is rising until it gets to TDC so anyone trying to "scrape the mud off the shoes" is applying positive force when the pedal is rising even if they are not thinking about "pulling up". Or those like you, because you are starting your "max power" application before TDC are also applying positive force when the pedal is rising even though you are not "pulling up".

I believe that best technique involves "scraping the mud off" well across the bottom and starting the "push over the top" well before the top, and complete unweighting in between, in addition to pushing down with substantial force. Focusing on only a small portion of the circle wastes a lot of potential IMHO.

In the natural 180 deg. or less pedalling power stroke the brain is working to a set pattern, as it applies that maximal down force it is also preparing the muscles of the other leg to get most out of that down stroke. Scraping the mud from your shoe etc upsets this pattern and concentration. Pedalling is a simple operation, why complicate it with extra activity that results in an overall loss of chain drive power. The only way to increase that chain drive power per pedal stroke without upsetting the natural pedalling pattern is to extend that power stroke to the full 180 deg. and increase the torque return from the maximal force you are applying. If you are not capable of applying maximal torque over the top, you are better off forgetting about that sector as a source of extra power.

 

[JayKosta]

Frank and Alex,
thanks for your info.

Continuing on the 'crank speed' and 'torque' issue, I think there are 2 primary ways that cyclists perform their 'pedaling technique', but it is certainly not all 1 way or the other - probably a mix of both in some ratio that is biased either way. The differences are probably due to aspects of the individual's mental and physiological makeup.

CRANK SPEED group - is more concerned with moving the cranks to achieve the desired rotational speed. And perhaps is also concerned with having a constant crank speed.

TORQUE group - is more concerned with applying power/force to the pedals to achieve the desired amount of work. And, again, perhaps is also concerned with having torque throughout the crank rotation.

I think EITHER method can produce good power output, and good results.

But it would be interesting (and beneficial?) to know what method is used by various top-performing cyclist.

I think my primary style is about 70% TORQUE, and 30% CRANK SPEED. When I put more emphasis on CRANK SPEED it takes a lot of mental concentration and I need to think more about my muscle use.

FRANK, do you have any input from your PC users about whether they view the PC training as improving speed or torque?

Jay Kosta
Endwell NY USA

 

[FrankDay]

Frank and Alex,
thanks for your info.

Continuing on the 'crank speed' and 'torque' issue, I think there are 2 primary ways that cyclists perform their 'pedaling technique', but it is certainly not all 1 way or the other - probably a mix of both in some ratio that is biased either way. The differences are probably due to aspects of the individual's mental and physiological makeup.

CRANK SPEED group - is more concerned with moving the cranks to achieve the desired rotational speed. And perhaps is also concerned with having a constant crank speed.

TORQUE group - is more concerned with applying power/force to the pedals to achieve the desired amount of work. And, again, perhaps is also concerned with having torque throughout the crank rotation.

I think EITHER method can produce good power output, and good results.

Of course either method can produce good power output no one would deny that both Armstrong and Ulrich were able to produce "good" power despite having completely different approaches regarding speed and torque. The question then becomes what is optimal and a further question is "can more be done"?

But it would be interesting (and beneficial?) to know what method is used by various top-performing cyclist.

And, it is not particularly good evidence that the best riders are using one method or another as to what is best because we don't know what else they are doing to become "best" since both Ulrich and Armstrong (and probably almost everyone else in that era) were doping.

I think my primary style is about 70% TORQUE, and 30% CRANK SPEED. When I put more emphasis on CRANK SPEED it takes a lot of mental concentration and I need to think more about my muscle use.

Any technique that requires the rider to think about when riding is likely to be less than optimal, at least for any event lasting more than a few seconds.

FRANK, do you have any input from your PC users about whether they view the PC training as improving speed or torque?

Yes. And what they report seems to depend upon what they race. Most road racers/triathletes report that their preferred cruising cadence seems to drop about 10 RPM from where they were before. Under these circumstances I think efficiency predominates and higher cadences for any given power are less efficient. But, track riders, who are forced to race on fixed gears, need high cadences to obtain high speeds. I had one user tell me that in 6 years of PC use he had been able to increase his max unloaded cadence from 185 to 245. High cadences are necessary to achieve very high power (if they can only be sustained for short periods). I had another long time user, a junior woman (she started them when she was 12) who races both track and road, report that when she was first invited to the OTC (I think she was 15-16 at the time) and tested that she tested to have the highest unloaded RPM ever seen there in a woman, again at 245. I believe high cadences are limited in most due to poor coordination and an inability to get the lifting leg "out of the way" at very high pedal speeds. The PowerCranks seemed to fix both of these limitations for these riders but it takes a lot of time to achieve those very high cadence numbers.

 

[FrankDay]

In the natural 180 deg. or less pedalling power stroke the brain is working to a set pattern, as it applies that maximal down force it is also preparing the muscles of the other leg to get most out of that down stroke. Scraping the mud from your shoe etc upsets this pattern and concentration. Pedalling is a simple operation, why complicate it with extra activity that results in an overall loss of chain drive power. The only way to increase that chain drive power per pedal stroke without upsetting the natural pedalling pattern is to extend that power stroke to the full 180 deg. and increase the torque return from the maximal force you are applying. If you are not capable of applying maximal torque over the top, you are better off forgetting about that sector as a source of extra power.

If you want to restrict yourself to what you believe is natural why don't we talk about what is really natural to humans, running. In running all of the forces that provide power are backwards (the downward forces only support the body). To say we should be restricting our power production to the pushing phase because it is "natural" when the reason this is "natural" is we all learned the coordination on platform pedals, where if we pulled back, lifted on the backstroke, or pushed forward over the top with any force meant our foot would come off of the pedal, is just silly to me. Yet that is the philosophy of many more than just you (to include the entirety of the "just push harder" crowd).

 

[CoachFergie]

If you want to restrict yourself to what you believe is natural why don't we talk about what is really natural to humans, running. In running all of the forces that provide power are backwards (the downward forces only support the body). To say we should be restricting our power production to the pushing phase because it is "natural" when the reason this is "natural" is we all learned the coordination on platform pedals, where if we pulled back, lifted on the backstroke, or pushed forward over the top with any force meant our foot would come off of the pedal, is just silly to me. Yet that is the philosophy of many more than just you (to include the entirety of the "just push harder" crowd).

Nice that what you think happens is at odds with the well performed research that compares pedalling with and without cleats (no difference), pedalling effectiveness (less effective = more power), being instructed to change the application of power around the pedal stroke (no improvement in power), changing crank length (no improvement in power or efficiency), using a crank that forces you to change the application of power around the stroke (no improvement in power and only 1 study saying an improvement in efficiency and every subsequent study saying there isn't), using elliptical rings (no improvement in power expect for a very short term test).

Maybe what you think is just thrown out there to sell Gimmickcranks.

 

[FrankDay]

Nice that what you think happens is at odds with the well performed research that compares pedalling with and without cleats (no difference), pedalling effectiveness (less effective = more power), being instructed to change the application of power around the pedal stroke (no improvement in power), changing crank length (no improvement in power or efficiency), using a crank that forces you to change the application of power around the stroke (no improvement in power and only 1 study saying an improvement in efficiency and every subsequent study saying there isn't), using elliptical rings (no improvement in power expect for a very short term test).

Maybe what you think is just thrown out there to sell Gimmickcranks.

Hey Fergie, by what mechanism do you explain the finding that "less effective means more power"? I know this is what they found but how is this explained? From this study that you think is so wonderful it would appear that we should all be working on developing a less effective pedal stroke and the worse it is the better for the racing.

 

[coapman]

If you want to restrict yourself to what you believe is natural why don't we talk about what is really natural to humans, running. In running all of the forces that provide power are backwards (the downward forces only support the body). To say we should be restricting our power production to the pushing phase because it is "natural" when the reason this is "natural" is we all learned the coordination on platform pedals, where if we pulled back, lifted on the backstroke, or pushed forward over the top with any force meant our foot would come off of the pedal, is just silly to me. Yet that is the philosophy of many more than just you (to include the entirety of the "just push harder" crowd).

Instead of pulling back and lifting, my leg is drawn back and up (mentally ahead of the rising pedal). This is because the leg has to be up and ready at 11 o'c to simultaneously start the power stroke at 11 o'c as the other leg's power stroke ends at 5. Not unweighting during the upstroke is probably caused by the two dead spot sectors at 12 and 6, the upstroke becomes an extension of the that idling.

 

[FrankDay]

Instead of pulling back and lifting, my leg is drawn back and up (mentally ahead of the rising pedal). This is because the leg has to be up and ready at 11 o'c to simultaneously start the power stroke at 11 o'c as the other leg's power stroke ends at 5. Not unweighting during the upstroke is probably caused by the two dead spot sectors at 12 and 6, the upstroke becomes an extension of the that idling.

You must be quite the mental giant. I find it impossible to concentrate on both the right and left legs at the same time when they are doing two different things. And, the last sentence is incomprehensible to me.

 

[sciguy]

[quote=FrankDay;1122029]You must be quite the mental giant. I find it impossible to concentrate on both the right and left legs at the same time when they are doing two different things.[/QUOTE]

Do you mean like athletes need to do when they use PowerCranks?

 

[FrankDay]

Hey Fergie, by what mechanism do you explain the finding that "less effective means more power"? I know this is what they found but how is this explained? From this study that you think is so wonderful it would appear that we should all be working on developing a less effective pedal stroke and the worse it is the better for the racing.

Fergie (or anyone else in that camp), I am waiting for an explanation as to how you explain that pedaling effectiveness and pedaling efficiency are inversely related. This result would seemingly predict that maximum efficiency would occur when pedaling effectiveness is zero. Or, if not that, what is the optimum amount of pedaling ineffectiveness to maximize power/efficiency?

The problem I see here is you guys don't really read this stuff and consider the implications but, rather, as soon as you see a result that seemingly supports your bias jump on it without any further thought.

Anyhow,I ask again, by what mechanism can you explain this result and what predictions can you make from it? I can do it. Let's see what you come up with. You can enlist the aid of Dr. Martin or Dr. Coggan (or anyone else) if you need to. Good luck.

 

[CoachFergie]

The problem I see here is you guys don't really read this stuff and consider the implications but, rather, as soon as you see a result that seemingly supports your bias jump on it without any further thought.

Quite rich coming from the master of cherry picking studies and often resorting anecdotal or fabricated stories to peddle Gimmickcranks.

 

[CoachFergie]

Hey Fergie, by what mechanism do you explain the finding that "less effective means more power"? I know this is what they found but how is this explained? From this study that you think is so wonderful it would appear that we should all be working on developing a less effective pedal stroke and the worse it is the better for the racing.

Probably pretty well explained by either event (sprinters less effective due to the gear selection etc) or the experience of the rider (the cat 1 time trial riders had more specific training experience). I don't train pedal stroke. I coach cyclists to meet the demands of their specific event.

Apart from your's and Noel's absurd claims I don't see anything in the literature that would make the magnitude of improvement worth focusing on such a minor detail.

NZ Track Cycling Champs start next Thursday so I have been down the track fine tuning things with some relatively new riders working on staying aero, holding their lines at 60-70kph, pacing, warm up process, recovery between events, gear selection as these things can make a big difference among other things.

 

[coapman]

You must be quite the mental giant. I find it impossible to concentrate on both the right and left legs at the same time when they are doing two different things.

That's what people have been trying to tell you, and is why circular pedalling is less effective than mashing. In my case it happens naturally because no work (torque) is being done between 5 and 11, so total concentration can be given to the power stroke between 11 and 5 o'c. Most effective torque application needs total concentration. With circular pedalling you are continually using split concentration, the weakest muscles generating minimal torque require the same concentration as the most powerful muscles that are supposed to be applying maximal torque.

 

[FrankDay]

Quite rich coming from the master of cherry picking studies and often resorting anecdotal or fabricated stories to peddle Gimmickcranks.

Fergie, Does it matter if I am cherry picking? I am simply asking for you to give everyone a mechanism that explains the inverse relationship between pedaling effectiveness and pedaling efficiency found by Mornieux et. al. and posted by Martin as seemingly significant. Did Mornieux give a mechanism to explain this seeming dichotomy? Martin? Anyone else?

One of the purposes of science is to understand the world. It isn't enough to gather data but rather use that data to help one understand the underlying mechanism that explains it. So, Mornieux presented some data. How do you explain it? Does your explanation allow you to make any predictions that can be tested? If your explanation allows you to make predictions and those predictions are correct then you are, perhaps, on your way to a greater understanding of what is going on.

So, let's hear how you explain that data.

 

[FrankDay]

In my case it happens naturally because no work (torque) is being done between 5 and 11, so total concentration can be given to the power stroke between 11 and 5 o'c.

I can pretty much guarantee you that you are wrong here, especially since you have done zero work trying to develop this part of the stroke. If you learned to ride a bicycle on platform pedals it is not "natural" to apply zero torque on the upstroke. You, like almost everyone else, are doing negative work between 5 and 11 (or 6 and 12), the only question is how much. If you think otherwise I look forward to seeing the proof of what you do.

 

[FrankDay]

Probably pretty well explained by either event (sprinters less effective due to the gear selection etc) or the experience of the rider (the cat 1 time trial riders had more specific training experience). I don't train pedal stroke. I coach cyclists to meet the demands of their specific event.

That is not a mechanism.

Apart from your's and Noel's absurd claims I don't see anything in the literature that would make the magnitude of improvement worth focusing on such a minor detail.

You are dodging the question. If you cannot explain it you don't understand it. Yet you keep throwing it out as being significant. Why, if you don't understand it?

NZ Track Cycling Champs start next Thursday so I have been down the track fine tuning things with some relatively new riders working on staying aero, holding their lines at 60-70kph, pacing, warm up process, recovery between events, gear selection as these things can make a big difference among other things.

Cool. When you get a chance address this issue. Or, just stay away and let those who might be able to comment on this dichotomy (you do see it as a dichotomy don't you?) join the discussion.

 

[CoachFergie]

What I do understand is that the only people trying to claim this stuff is important is some crank in Ireland and someone selling a product to fix a problem that doesn't really exist.