hyhuu

If you are riding hand-free, else that's not true.

CliffordK

That is absolutely false.

When pulling up while standing, the force pulling up is added to the force pushing down... So you essentially get DOUBLE the force/power from pulling up.

While sitting, it is unclear. Some of the quoted papers seem to fix the energy output, and even the RPM, so one would expect a tradeoff, add power in one place and loose it elsewhere.

Your body will have two different types of effort, both are necessary in cycling. There is an endurance level, maintaining effort for hours of cycling. This may be somewhat cardiovascular limited, so it would not be unexpected to see tradeoffs. Add power in one place and loose it in another.

The other type of effort is sheer anaerobic power. Here you wouldn't necessarily expect to find any trade-offs, and should expect to see gains by using more muscle groups.

Perhaps a third type of effort is that related to a cumulative muscular fatigue. As I find myself plodding along, I find that I just don't have much extra to push into the downward muscles. However, if I haven't been pulling up for some time, those muscles may be fresh, and good for an extra short boost of energy.

The final element is that horsepower is a rating of power + time. With cars, one often finds a little tiny engine spinning at extreme speeds can match the horsepower of a big engine spinning at slow speeds. In cycling, once one starts maxing out the downward forces, then one must either spin faster, or pull up.

Leinster

No you're not. This has been explained to you already. The pull-up and the push-down force are both acting in the same direction about the axis of the bottom bracket. If 2 forces are acting in the same direction, their vectors are added, not subtracted.

gregf83 

what has been published regarding pedalling during high-output sprint efforts? Please share. Or are you just a smart-ass with nothing to contribute?

Stucky

But you're overlooking one thing: You can not exert maximum force pushing with one leg, while exerting a strong force with the other leg in the opposite direction. If both legs were working in the same direction, it would be a different story- but when applying opposite forces....our bodies just don't work that way.

You refer to non-existent studies to refute my contentions, and I'm a suspected wise-ass? [gasp]

Nope, I don't know of any such studies; They may or may not exist (just like yours- unless of course yours were conducted by Tom Shimano and Dick & Harry Crank; and Bob Speedplay....)- I don't even read the ones I am aware of, because Iput about as much faith in such things as i do dietary studies, like the ones which warned people for the last 40 years to use vegetable oil and avoid eggs, butter; and salt.....and now they've just suddenly done a 180 on all of that, and everyone just goes along with it)

My opinions on this subject are formulated by nothing but my own personal observations. I use clipless; I like them; I live in the hills; but they are not a magic bullet; they're just a convenience; and, like a lot of other cycling accessories, their benefits are very subtle.

CliffordK

Bacciagalupe Posted a diagram of high cadence, high power sprint. Post #82, middle diagram. Unfortunately he did not include a link (or reference) the primary source.



As I later pointed out, the rider is actually pulling up with almost 8.3% of the force that he is pushing down with (not counting the unloading force) while spinning at 120 RPM.

What we're missing so far is a good comparison of data for standing hill climbs at low cadence. That data has to have been tested and published... somewhere?

Apparently Armstrong was a big proponent of seated spinning hill climbs. Is that it?

gregf83 

I only have personal observations that while sprinting or going hard up a hill or starting from a stop I pull up on the pedals and gain significant additional power somewhere other than the downstroke. Further, I contend it is necessary to have your feet firmly attached to the pedals in order to see these benefits. As well I pointed out that track cyclists use clips and straps to hold their feet on the pedals.

Presumably your contention is that being clipped into pedals provides no (or negligible) performance benefit while sprinting. Is that correct or am I misinterpreting what you are saying?

Bacciagalupe

Researchers have, in fact, used pedal-based power meters for years. There is a lot of research which proves that when you're pulling up, you are not contributing power directly to the drivetrain. I showed graphs from 3 studies in post #86 .

Do you really need me to post a wall of links? Would you read them if I did?


Heavy riders don't necessarily provide more power to the drivetrain. I have absolutely no doubt that a 135-pound pro cyclist can generate substantially more power, and for a longer period of time, than an out-of-shape 200-pound 5' 8" rider.

More importantly, not seeing anything that contradicts the very clear data, which shows that no one applies power to the drivetrain on the upstroke. What you're doing is lifting your leg (or, if standing, most of your body's mass), which means more force of the dowstroke gets applied to the drivetrain. I.e. it's just not additive.

Yet again, a cyclist is like a two-stroke engine. Not that difficult.

And yes, in the same way you need a blood pressure meter to know your blood pressure, or a speedometer to accurately know your speed, you need pedal-based power meters (or something similar) to accurately determine when you're applying power during your pedal stroke.


The evidence from the study linked earlier indicates that it's less efficient. You wind up generating less force on the downstroke. It also forces your body to work inefficiently, i.e. gross efficiency falls.

CliffordK

Whenever I quote somebody else's work, I generally like to attribute it back to the author, or source I got the information.

I have the link to the first graph. It is from the paper that the OP had posted in abstract. And, yes, I did read it.

The second one seems interesting as it does cover a maximum power situation, so yes, it would be nice to see more than a single graph from the paper.
The third one... again, I like to attribute work, but it seems to be similar to the first one. But, still methods would be interesting.
I did read the introduction in the one paper which was interesting, and certainly seemed to indicate more ambiguity than people are indicating here.

A confusion between power and force.
When standing on the pedals, the force entered into the pedal is essentially the weight of the person, adjusted by factors such as the weight or pulling force applied by the arms, and the lifting force on the opposite pedal. Perhaps you could also factor in the acceleration due to gravity, 9.8 m/s[SUP]2[/SUP] which may become significant with different cadences.

Power is related to force, distance, and time, and thus also requires adding in the length of crank arms, and the cadence.

If both the heavy and light riders were doing a 40 RPM standing hill climb, it would be difficult for the light rider to generate the same power as the heavy rider. I.E. The 135 lb rider would have to pull up by 32.5 lbs just to get to the point where the 200 lb rider is just pushing down without pulling up.

Of course, the overall speed of the light rider may be quicker if they are outputting the same power.
None of the data I've seen presented here shows power on a standing hill climb which is where many people object to such sweeping statements. Even on the level, some people do pull up, at least from time to time.
One is generating less force on the downstroke only if one is artificially limiting the power output with a specific target as was done in the first study you linked to. I.E. There is a trade-off to generate the same power. When on the saddle, there may not be a decrease in power. When standing, there definitely IS NOT.

Say you crank with two pedals vs cranking with one pedal. If you 're generating the same speed with the two pedal crank as the single pedal crank, then you'll be generating about half the power on each side.

I don't know about overall efficiency. I don't see that data here. However, during a sprint, it is not necessarily about efficiency, but rather getting to the finish line first. VO[SUB]2[/SUB], lactic acid, whatnot makes no difference during that final 30 seconds.

Hill climbs are tricky, but perhaps it depends a bit on whether it is the last thing in the ride vs knocking oneself out in the middle of the ride.

Stucky

I basically agree. The only thing I would add, is that you in fact LOSE some power on the downstroke while pulling up with the other leg.


I agree that being firmly attached is a necessity, and does provide a performance benefit over not being attached.

No, that is not my contention. I'm just saying that any benefit of being clipped in is NOT from gaining power by being able to pull up with the opposite leg; because what little power you put into that pull, is essentially subtracted on the push on the other side.

I do respect your observation though. I almost thought the same thing, the first few times I rode with clipless- but then I realized what I said above. That, and the fact that my time didn't improve any compared to when I was using loose clips and straps. But that is just my experience, in my situation- Granted, it could be different for you, but from what I've seen, the evidence is to the contrary- but you also make a point in that perhaps the scenario was never tested with just sprinting.

....ummm...so where are we, again?

Stucky

^THAT is exactly what I have observed in my own cycling, and what I'm tryin to say.

mercator

This is incorrect. Review your physics 101.

ursle

Let me make this very simple to understand, the upper leg has muscles on the top or front of the leg that contract to lift the leg, the back of the upper leg has muscles that when contracted push the leg down (pull if you wish) if only using the back of the legs when riding, 1/2--- the stroke is being ignored, and the lower body is going to get out of balance rather quickly, but if both sides of the leg are being used regularly, a more efficient stroke is made, the lower body is much more balanced. This debate rather amazes me.

The bicycle is the most efficient means of ground transportation, why not utilize it properly.

Bacciagalupe

Whenever I give people a link to these kinds of papers, they usually ignore it. Let's see what happens.

These papers cover various topics. Some address issues like cadence, but also include the all-too-familiar graph which show little or no torque applied on the upstroke. Some discuss short-term power, some discuss climbing, etc etc

https://www.setantacollege.com/wp-con...Mechanical.pdf
Optimal cadence selection during cycling
https://www.deepdyve.com/lp/the-amer...ise-A0PNFmvDbh
Seated Versus Standing Cycling in Competitive Road Cyclists
https://www.fredericgrappe.com/wp-con...%20cycling.pdf
Book excerpt: The biomechanics of pedaling, from Andy Pruitt?s Complete Medical Guide for Cyclists - VeloNews.com

And one more set of images for you... This one is the force vectors applied to the pedals while seated and while standing, clipped in, using Metrigear (which became Garmin Vector). Note that the force is almost always down and slightly back, and is never up:






And again, a 135 pound pro can unquestionably produce more power than a 200 pound amateur who's standing on the pedals. So, I'm clear on what you're trying to prove.


Good news! The truth is out there.
Level ground and uphill cycling efficiency in seated and standing positions

"Conclusion: Gradient or body position appears to have a negligible effect on external efficiency in field-based high-intensity cycling exercise. Greater short-term power can be produced in standing position, presumably due to a greater force developed per revolution. However, the technical features of the standing position may be one of the most determining factors affecting the metabolic responses."


By this point, I believe I've shown you at least a half-dozen graphs which show that pulling up doesn't provide direct power to the drivetrain. This includes on inclines, at different cadences, in steady state conditions, and at maximum effort. Now do you believe it?


They were targeting 90rpm, and an individual's 60% MAP. The results are the same as in the Korpf paper -- when you pull up, you reduce your losses on the upstroke (not produce positive power, but merely reduce losses) and reduce peak power on the downstroke. The protocol is not distorting the conclusion.


I'd say it does. After all, if a sprinter goes 1 second too early, and runs out of gas in the final 1 second, that's not solely because her muscles are fatigued. It can also be because she went too hard, too fast, too soon and/or otherwise ran out of fuel. Pros who face the rare intermediate sprint also won't want to blast through all their glycogen reserves halfway through a stage.

Stucky

It's not just about physics. It's about physics and anatomy/physiology/etc.

Our legs are not hydraulic cylinders. Our legs can only utilize a fraction of our muscle power when pulling up. Doing so [for the 85th time] may feel right, but it produces a zero net-sum gain, in that it reduces how hard we can push down with the other leg at the same time, and at the same time it reduces the resistance of the downstroke pedal.

While I can understand anyone not taking my woird for this, since i am a mere layman, and my opinion was just formulated by what I have personally observed- Bacciagalupe has provided the relevant scientific data which agrees with my conclusions. I think the trouble is, the idea of "pedaling efficiency, byutilizing the upstroke" has been so ingrained in cyclists for the last 15 or 20 years through marketing campaigns, that everyone just believes it, without realizing why they believe it.

achoo

Quads are much larger muscles than hamstrings. What are you basing your assumption that balance is better on?

Hell, first define "balance".

And what makes you the judge of whether or not someone is "utiliz[ing] it properly" anyway?

gregf83 

I'm not sure why you think the force you pull up with subtracts from the other leg. It's certainly possible to push hard with one leg while pulling up with the other.

In any case I did do a test for my own curiousity a little over a year ago. I went for a brief ride with platform pedals and then did the same loop with clipless. I included a couple of brief sprints as well as a steep hill (Imp Hill) and a couple of 5 min sections at 300W. There was essentially no difference in my HR on the two 300W sections and I didn't find it a problem riding with the platforms which agrees with the research papers for steady state riding. The sprints on the other hand I was able to put out more power with clipless. Unfortunately, there was no money on the line so you'll just have to take my word that I was trying hard on both sets of sprints

I've attached a summary of the test results from Golden Cheetah. Doesn't prove anything, just my personal observations:

gregf83 

I don't think anyone is disputing that pedals aren't going to make much of a difference for steady state riding. All of your examples are for relatively low power steady state riding. Standing on the pedals up a hill at 300W is no different than a seated climb at 300W. Try the same hill at 1000W and see how well the platforms work.

edit: And I'll ask again, if no power is applied but on the downstroke why do track sprinters need to be clipped and strapped into their pedals?

mercator

I'm sorry if I misunderstood you, but you indicated previously that pulling up on the backstroke subtracted from the force on the other pedal. This is demonstrably false.

Here is a thought experiment you can try at home. Put one foot on your bathroom scale and bolt the other foot to the floor. Standing at rest, the scale should read about half your weight.
Now pull up with the secured foot. What does your scale read?

Bacciagalupe

Well....

This is clipped in. By now, the shape of the graph should be familiar. Since riders still aren't applying much power to the drivetrain, I don't see much reason to assume pulling up will work much differently than in any of the other tested conditions.



From https://www.researchgate.net/publicat...370d4b575a.pdf




1) Significantly better control of pedaling and handling.
2) Keeps the fit precise.
3) Abundance of caution.

If you're riding a fixed-gear bike at a high RPM and a high power output and you lose contact with the pedal, you're probably in serious trouble. Thus, many track sprinters use extra caution and use both clipless and straps, although it's probably not necessary these days to do both.

There is a 1997 study that sprinting with and without toe clips, which claims that foot retention increases the maximum power output -- but rather oddly found that maximum and peak velocity didn't increase, and concludes "the kinetic energy of the legs can be transformed into power output when cycling without toe clips as well as it can when cycling with toe clips." I haven't read it yet, so I can't explain the conclusion.

Torque-velocity relationship during cycle ergometer sprints with an... - PubMed - NCBI

Stucky

Ah, but the problem is, your test does not reveal WHY the clipless enabled you to put out more power in the sprints. In fact, if it were due to you being able to transfer more power due to the ability to pull up, then you should have realized the same benefit on the hills.

And remember, I'm not doubting that any form of foot retention provides more efficiency than no foot retention- especially in sprints.

Posting your test results did give me an idea, though: Maybe I should start naming the hills around me! "Alp De Hernia"; "Cardiologist's Boat Payment"; "The Widow-Maker"

Stucky

Yes, your understanding of my understanding was not a misunderstanding .

The scale experiment is flawed, in that it's testing total weight which is resting on it; and balance; and not the utilization of power by the individual leg.

Bacciagalupe has posted the pertinent info, which is far more accurate and comprehensive than my simple observations or yours. But you know? Since a good part of cycling (or just about any sport) is psychological, maybe we shouldn't engage in discussions like this; 'cause the way our noggins work, if we THINK we're increasing our power and efficiency by pulling up, we're liable to act as though we really are, eh? (Why kill our buzz with facts? )

mercator

Quoting from the abstract:
The point of the article is that the pedaling method doesn't affect maximum velocity, likely due to limits of the riders ability to sustain power output. In no way does it support @Stucky's assertion that pulling up reduces the force applied to the pedals.

gregf83 

my read of that graph confirms what I've been saying. There is significant power being applied from 180 to 360 degrees. Would you want to give up that power in a sprint? It looks something like 5-10% and based on my own experience I suspect it is much higher at low cadences like you would see in a standing start at the track. I believe the extra power goes away completely at high (180rpm) cadences.

Bacciagalupe

You mean, partially quoting from the abstract. I explicitly stated that this study showed an increase in watts -- but no changes in velocity. The very next line reads:

"In contrast, the maximal extrapolated velocity, V0 and peak velocity were not significantly improved by the use of toe clips. The comparison of the angle-torque patterns at low and high velocities suggested that the kinetic energy of the legs can be transformed into power output when cycling without toe clips as well as it can when cycling with toe clips." (Emphasis added)

Again, I haven't read the article, so I cannot clarify this apparent conflict.