Bacciagalupe

It's a metaphor, not a literal assertion. It's apt, because:

• You are applying one burst of power per revolution.
• You are not applying consistent levels of power throughout the pedal stroke.
• The upstroke is driven mostly by momentum.
• You still wind up with a consistent speed.

What am I missing?

Bacciagalupe

For sprinting and racing, I recommend clipless. I use clipless. I am NOT anti-clipless.

Go back to my first post in this thread, #52 . I explicitly stated several advantages of clipless. One of them was "staying attached to the pedals when applying lots of power."

At no point in this thread, have I stated that clipless causes any problems, or reduces power output, or are somehow more dangerous.

The points I'm trying to make are much more specific:
• Foot retention does not increase power to the drivetrain.
• Foot retention does not fix a poor pedal stroke.
• The data is very clear: You don't apply power on the upstroke.
• The advantages of foot retention are about control and ride feel.

pallen

That's odd because the study you keep referring to says:

• Foot retention can increase power to the drivetrain, but its less efficient.
• Pedal stroke technique is irrelevant. (the entire point of the study)
• The data is very clear: You don't apply power on the upstroke on flat, level, steady-state riding. The data does not address standing, sprinting, or steep climbing.

Icculus21

Here's the plain and simple truth: Once you go clipless you never go back!

cooker

It can in the short term.

cooker

I'm an urban commuter. I used clipless for a couple of years and went back. It's much easier for me to ride on flat pedals. No loss of power or efficiency at moderate speeds on flattish ground, no need to change shoes, no having to click in and out. However, this is the road cycling forum so in that context I guess you're right.

Brian Ratliff

But see, this is just wrong. What you really mean is that clipless does not increase pedaling efficiency under steady state pedaling conditions; it most certainly allows for more power into the drivetrain.

pallen

Right, and the study clearly states this in their conclusions,
"Although our results suggest that actively pulling on the pedal reduces gross efficiency during steady-state cycling, there may be situations during which an active pull is beneficial in terms of adding power to the crank"

Brian Ratliff

Why not just "piston", since the "two-stroke" part refers specifically to how the otto cycle engine ejects its exhaust. Last I checked, my legs don't need to exhaust spent fuel every pedal revolution.

Brian Ratliff

Well, there you go.

WhyFi

That'd make drafting a *****.

Bacciagalupe

That's odd, because I've cited numerous sources for my beliefs. I also haven't referred to the Korff study in several recent posts.

Another source (not yet cited) is Edmund Burke:
Burke does suggest that some elite sprinters are capable of, and might even benefit from, effective forces on the upstroke. But it's clear that:
1) Even in those situations, it's a small amount of power.
2) No one reading this thread is in that league.

So, yeah. There's a lot of data which indicates that the overwhelming majority of cyclists do not apply power to the drivetrain on the upstroke, and all you're really doing is getting your leg out of the way.

And again, this isn't really a "platforms vs clipless" argument. It is simply that even when you're clipped in, you aren't really applying force to the drivetrain on the upstroke. All you're doing is getting your leg out of the way.


Yes, my point (and apologies if it got buried) is that it's the same as low cadence. A lower cadence produces more force, but winds up reducing gross efficiency. I.e. it feels more powerful, but is in fact less efficient. That's why there are very few situations when you'd want to mash.


Actually, the purpose of the studies was to see what, if any, differences there are between pedal strokes. And again, both studies on pedal strokes indicated that intentionally pulling up reduces net/gross efficiency. (The Korff study indicated that there was no significant difference between "circles," "pushing" and "preferred.")


I believe I already addressed standing, albeit briefly. Here are the force vectors when standing:



Basically, at no time are you actually pulling the pedal upwards while standing. You're applying significantly more force on the downstroke, but also weighing down the pedal on the first third of the upstroke.

When seated, you're just lifting your leg. When standing, you have to lift most of your body, which creates significant negative force on the pedals.

Climbing shouldn't be any different. You still want to maintain a high gross efficiency, and apparently being on an incline doesn't make a significant difference to your pedal stroke. (e.g. https://link.springer.com/article/10....421-011-1914-3)


Now, if you can produce some actual data which modifies or corrects my views, I'd be glad to hear it. Oddly enough, I still haven't seen any contrary data. That's OK. I'm a patient guy.

Bacciagalupe

Let me be even more specific.

• With the possible exception of a small cadre of elite sprinters: Everyone exerts some negative forces on the upstroke.
• This is (presumably) because you are exerting power to lift your leg, and can't lift it fast enough to completely get out of the way.
• As such, a small amount of power on the downstroke is wasted lifting the other leg.
• You do benefit from lifting your leg, as that maximizes power going to the drivetrain.
• You are not actually adding power to the drivetrain on the upstroke.

And again, without a pedal-based power meter, there is no way to know what is actually happening when you're pulling up. You could be exerting a very small amount of force and feel like you are tugging on the pedals. Or, you could just not be noticing how you're exerting negative force at the bottom of the pedal stroke and going to zero or a very small positive at the 12:00 position. Without objective measurement, you just don't know.

And while I agree that I haven't seen specific data on this: As long as you stay in control, I see few reasons why platforms would be all that much different. The main exceptions are high-power high-cadence situations, where maintaining contact/control would be extremely difficult without foot retention. And even then, it's not that "the upstroke provides power." It's that "being clipped in makes it possible to get your leg out of the way without losing contact/control."

This is not an anti-clipless argument, though. It simply rejects the belief that you gain huge power advantages (especially in ordinary cycling conditions) because of foot retention, as quite a few people seem to believe.

Is that clearer?

Bacciagalupe

I have no objection to a piston metaphor. Of course, metaphors aren't supposed to be hyper-literal, but whatever floats your boat.

Bacciagalupe

Yeah, you're hanging an awful lot on that speculation. And ignoring all the other data, apparently.

This point is now covered in my comments re: Burke.

pallen

Well, considering most of us are not in a position to have access to studies, we probably wont find data. Does that mean it doesn't exist? I don't know. All we get from you are snippets and your interpretations. When I was able to find one of the actual studies you referenced, I found that they came to very different conclusions than what you were presenting here. The study I found made perfect sense in its context - I found nothing to disagree with there.

I know many times when I'm standing, I am doing what you show in the graph above - especially on flat, steady-state cycling. I know that when I am sprinting, or climbing something steep and standing, the dynamics change dramatically. There's standing and there is standing and cranking up a 8% grade or a full-on sprint. I have pulled up enough to come unclipped from my pedals. That is significantly more than just getting my leg out of the way.

When you say "Basically, at no time are you actually pulling the pedal upwards while standing." I don't think you prove anything with the accompanying graph because the context of that graph is not given. Was that done on a trainer at steady-state? If so, I would say, like the other study, I probably agree with all of their conclusion too. Unless you have some thing that clearly states that it was measured in a steep climb or in a sprint while standing, I'm going to assume that my own observations are correct. For cruising along - I completely agree with everything you have presented. There is no significant "pulling" happing in that kind of scenario, even when standing.

pallen

I agree with all the other data - it was not collected in conditions relevant to what we are discussing though. You cannot take steady-state cycling measurements and declare that no significant power is added in all situations. The data can only tell about the conditions in which it is collected.

RJM

I am surprised in the year 2013 we are arguing over the benefits of foot retention on bicycles. I think that argument was finished back in the, what, 50's, 40's, maybe 20's???

Clipless are a hell of a lot better than clips and straps, period.

cooker

Okay, so I see part of the problem here. "Pulling up" increases delivery of power to the drive train, because more muscles are at work. However, perhaps you are saying that the driving force is still being applied on the downstroke, and all that the pulling up is doing is lessening the deadweight on the upward bound pedal. However, even if that is always true (which is dubious) you are still delivering more power to the bike, and going faster (for the moment, until you get tired or acidotic).

LamontC

How is it possible that someone could post nearly 6,000 times on a bicycle forum and never encounter a steep hill on a bicycle? I ride on hills that are steep enough that my body weight won't produce enough force to keep the crank turning in low gear (more frequent on mountain biking trails than on the road, but it occurs in both places). What would be the right thing to do there? Roll back down the hill, or apply some additional force by levering against the handlebars and pulling in both directions (up and down) on the crank?

Brian Ratliff

1) it is a lot more power than you are willing to address. Direct experience: takes precedence over some study published by inexperienced academics funded by pocket change with test subjects numbering in the single digits drawn from a pool of people hiring out the researcher's coaching services (mostly triathletes and aging rich guys).

2) I'm in this league. If your point is limited to triathletes, then you should probably admit to as much.

You are committing the primary amateur sin of extrapolating data outside the context of the study. The data in the study addresses only the parameters tested in the study. There are many different types of pedal strokes a cyclist might use, depending on his or her need for efficiency vs. power. The research was testing "cruising" pedal strokes, apparently; pedaling technique aimed at steady state power and efficient delivery. Basically only testing steady state cycling. But anything involving hard accelerations was evidently not tested in the studies you believe in.

Highlighted is the key limitation of the results. These results do not apply across the entire spectrum of cycling.

Brian Ratliff

Of course you can. Your body is a sensor, if you care to pay attention. What ever would we do without advanced technology! We wouldn't know anything!!

And... what's good for the goose is good for the gander. I think we are done here. You don't get to throw around data like it's Christmas then claim a conclusion built on an unsupported extrapolation.

cooker

Do those upward arrows make my butt look fat?

Brian Ratliff

You have heard plenty of contrary data. You simply don't believe anyone without nine test subjects and a pocket change budget with a coaching service to shill.

thump55

I did a steady, long climb (well for around here anyway) last night. I paid special attention to my pedal stroke and what I was feeling just for this thread.

What I noticed was not a steady push-pull. The push was still 95% of my effort, but every minute or so, I could feel the pull get stronger for just 3-4 pedal strokes, but enough to give my quads a tiny reprieve.

To illustrate the importance of that brief rest and the good it does, take a heavy book and put it in the palm of your hand. Stretch out your arm straight to the side and hold the book up as long as you can. When you can no longer hold the book up, rest you arm for 4 seconds, then put the book back out. If you were at a "10" when you had to put the book down, you may be at a "7" when you put the book back out, after just a few seconds reprieve.

Now repeat that several times up a climb and you can see how clipless lets you maintain the same power for longer.