badamsjr

I got A520 SPD pedals to work with recessed-cleat MTB shoes. They are similarly sized to SPD SL pedals that I use on my road bikes. Almost normal walking, without the clanking of other types of cleats.

Looked at the A530, but decided they were not as wide as the A520, and the platform side would be too easy for some miscreant to ride off on.

Bacciagalupe

Again, not really. This belief is apparently based on old studies using slow-motion footage to analyze pedal strokes; more recent studies, using power meters in the pedal itself, indicate this is not what happens. You are only applying power on the down-stroke, and the rest of the time you can, at best, keep your other foot out of the way. You aren't applying a significant amount of force on the upstroke.

I.e. "pulling up hard" doesn't do anything. The best you can do is work to develop a smooth pedal stroke, and I don't think you necessarily need to be clipped in to accomplish that goal.

staehpj1

I tend to agree that with a smooth spin riders do not generally pull up much on the pedals. I disagree on what you seem to be implying that means. Specifically it does not mean there is no advantage to a foot retention system and does not mean that using one is not more efficient. The article does not state or even imply that is the case.

Also I think that while it is not part of a smooth spin, there are times when pulling up does occur and may help. While you may not do it when using an efficient spin, you may do it when near the top of a short climb to engage different muscles to get over the crest without down shifting. I personally believe that is helpful in some limited cases, but even if it isn't it does not negate the usefulness of clipless and other foot retention systems.

A few points...

1. The author says in the article, "The most they can hope for is to unweight the rear foot so it adds less drag to the power output of the foot that is pushing downward". That doesn't mean there is no gain from unweighting the rear foot. Even if it is an small difference it is repeated over several thousand pedal strokes per hour. So while it may be a small difference it still is a difference.
2. The article recommends that to learn that silky smooth spin you should practice one legged pedaling. Try that with no foot retention system sometime.
3. Whether you pull up or not you will not convince me that more power isn't generated over a larger portion of the revolution, especially not based on one person's read of one survey.
4. There are other differences as well. Not everyone may consider it an advantage, but I personally think the fact that my feet are always the same place at at the same angle on the pedal helps me maintain good form.

Bacciagalupe

I'm not saying clipless is "completely" worthless. Nor do I know Pruitt's position on the issue. What I would say is:

Even the best cyclists are not applying power on the upstroke. As a result, clips / clipless most likely has a much smaller impact than most "serious" cyclists believe. What's happening is that on the upstroke, your leg is apparently trying to "get out of the way" -- and this is probably more a function of a smooth pedal stroke than of having your foot clamped to the pedal.

The article also recommends using rollers and riding off-road to smooth out your pedal stroke -- neither of which requires clips.

And while you believe locking your foot in place results in good form, for many people the lack of float can cause knee issues.

Clips may be helpful in some ways, but I'm not convinced anymore that they are critical. A smooth pedal stroke -- which you can likely achieve with regular platforms -- is probably equally or more important. Otherwise, it looks to me like it's more a question of preference, convenience and/or comfort.

If you don't believe power is only applied on the downstroke, I highly recommend you re-read the article. Again, they're drawing conclusions based on power meters installed in the actual pedals, not from external observation or conjecture. So, when the author states that you apply power only on the downstroke, and that most of the time the applied forces are tangential to the pedal stroke, I see little reason to dispute it.

By the way, the data Pruitt uses matches (and may well be derived from) the preliminary results of the Metrigear system, which is an attempt to commercialize in-pedal power meters.

staehpj1

Probably due to the fact that they never bothered to get their pedals set up correctly in the first place in most cases. The few exceptions are people who have some unusual biomechanical issue.

I'd argue that developing that smooth stroke is easier with a pedal retention system like clipless.

I don't see anywhere in the article where he says there in no added efficiency. In fact he says, "Greg LeMond first described pulling through at the bottom of the stroke saying it’s 'like scraping the mud off your shoe.' The image still works." Here again that is facilitated by having a pedal retention system.

I do agree that this is interesting stuff, but nothing in the article compares riding with and without foot retention. Also nothing in the article implies that a foot retention system does not extend the portion of the stroke where you are making power.

Carbonfiberboy 

Uh, wrong. On subjects like this, I try not base my opinion on studies done by persons I do not know, on other persons whom I also do not know. I base my opinions on personal experience and first person discussions with other persons.

When out of the saddle, I sometimes pull up so hard on the upstroke, I lift the rear wheel right off the ground. That's what your heel cups are for. If you watch videos of Lance, you can see he uses his heel cups the same way. When loaded, Stoker and I will do the same thing to get over a little steep hump without gearing way down. We can do the same thing seated. It's very effective when one needs some extra power. When a bit out of shape, I cramp as frequently in the hams as in the quads. In fact, if I cramp my quads, I can pedal very effectively by using only my hams, no quads at all. Or switch off between them.

The fact that most people have an inefficient pedal stroke shouldn't stop one from developing a very efficient stroke. An efficient stroke is perhaps the main thing that's kept me riding with people 20 or 30 years younger than I. So I preach the gospel to anyone who'll listen. The way to get faster and ride easier farther is to use more of the muscles in your leg. That way, one can develop more power for short periods and tire more slowly. Spreading out the work among one's leg muscles is more efficient, even when one is aerobically limited, as on a long climb. What one wants to do, regardless of what each leg does, is to apply constant torque on the bottom bracket. That way there is no acceleration applied to the bicycle by any individual pedal stroke or part of a pedal stroke, and thus no wasted energy. So talking about force on the downstroke or upstroke is partly a distraction because it leaves out half the pedal stroke.

This is how one does what I and many other cyclists have found to be the most efficient, with each foot, starting at top dead center: push forward as though trying to kick a dog on your front wheel, then in the first part of the downstroke, let your leg weight come down with little apparent effort, then at about 120° begin pushing down and back, continuing the back pressure through to 210° or so. The bottom part of the stroke is very important because your leg is almost at full extension and your muscles have good leverage on the pedal. Continuing to pull back into the start of the upstroke makes up for not really pushing down at the start of the downstroke. On the upstroke simply unweight the leg, with the feeling of trying to throw your knee over the handlebars. Just before your knee stops its upward motion, begin pushing forward, thus applying torque at the top of the upstroke, and carrying that forward push into the start of the downstroke.

I've attached a graph showing the approximate desired force inputs into each crankarm. Adding the two torques together produces approximately the straight line at the top of the graph. Notice that probably half the total torque shown on this graph cannot be applied with platform pedals, needing either clips or clipless to push forward and pull back.

One-legged pedalling is one of the best ways to improve your efficiency, and is best done on trainer, rollers, or on a climb, being too easy to do on the flat.

cyclist2000

I use clipless when touring. I have quit using toe clips because I cannot find a good hard soled cycling shoe for toe clips anymore. I thought that the Sidis were the best shoes made for regular pedals, the had the best system for retaining the cleat.

Also with mtb shoes and SPDs it is possible to walk around without looking awfully strange.

If anyone knows a good cycling shoe that has cleats that can be used with toe clip and regular pedals, let me know.

JeanM

Those use cones, like the Shimano hubs and may be repacked from time to time, to last a almost your lifetime.

TimeTravel_0

MKS RMX pedals.

Bacciagalupe

Wait, personal experience trumps empirical scientific findings? Why didn't I get the memo?

This is not based on statistical surveys or conjecture. What they've done is put a power meter into the actual pedal itself, so these conclusions are drawn from direct observation of the actual forces applied during pedal strokes. Not only do these types of power meters measure when, where and in what direction the forces are applied, it also measures each leg independently. These studies pulled from a diverse pool of cyclists, including professional cyclists, MTB, track etc. The author of this article started these tests in 1996 and routinely works with a wide range of athletes, including elite riders.

The data gathered by this method typically looks like this, courtesy of Metrigear:



("Vector" is the name of their upcoming commercialized pedal-based power meter.) On the bottom graph, the gray (flat) line in the center is an average of the forces applied during the pedal rotation. Note how the forces applied drop to zero or less on the upstrokes -- and how the result is a consistent application of force.

Other data collections, by the way, point out how most of the forces applied during the stroke are tangential. If my understanding is correct: On the down stroke, you are not successfully putting every ounce of force into pushing the pedal down; you're actually pushing the spindle forward as well, which reduces the efficiency of the pedal stroke. So when you are pulling hard on the upstroke, most of that time you are actually just pulling the spindle back rather than up. (This shouldn't be too surprising, since the pedals use a radial motion rather than an up-and-down pumping action.)

Subjective assertions and anecdotes may be persuasive for some people. Ultimately though, without an objective measuring device, we humans have no better idea what our legs are doing during a pedal stroke than, say, whether we are working aerobically or anaerobically. There is now an empirical, objective, direct, repeatable and testable means to measure exactly how much force is applied to the pedal itself, and it's far more accurate than guessing what your legs do or watching videos of pros.

On a positive note, the emphasis is still on developing a smooth stroke, so you haven't wound up doing anything counter-productive. It just turns out that your underlying assumptions about what your legs are actually doing are incorrect, but you've wound up doing what you need to do anyway.

Carbonfiberboy 

I don't have to guess what my legs are doing for three reasons - one, I do a lot of one-legged pedalling on my rollers and know exactly what it feels like to keep a steady rim rpm; two, when pedalling with both legs I can feel the muscles contract, driving the pedals; and three, as I said, I can pedal with hams alone so I know I'm not powering on the downstroke.

The funny thing about your second graph is that the black, "average" line is obviously software generated and does average the power output, but over a much longer term than the individual pedal meters. Looking at the graph, one can see that both pedals drop to zero power at the same time, yet the black line doesn't move. It should also drop to zero power if it's showing what you think it's showing. There is simply no other way to interpret the second graph.

My pedalling looks exactly like the second graph when I stand, but when I sit it looks like the graph I created for my post. I'm definitely not alone in my pedalling style! I ride with many people who can pedal circles. It's easy to tell: the upper body never moves on a rider who is putting a constant torque on the bottom bracket. Riders who bob or move from side to side under heavy effort are applying torque as shown by your graph. Something to do with Newton's laws of motion, I believe. I can climb at cadences down to about 45 without moving my upper body. Below that, I have to start pushing down hard and do bob.

The first graph is a clear demonstration of what I'm saying! Look at that cadence bounce with the change of pedal angle! When I pedal rollers, i.e. almost no averaging from momentum, the rollers make a constant noise. My cadence does not vary with pedal angle, which is what I'm talking about. So when riding in the saddle, no momentary accelerations.

Your "scientific" graphs, while undoubtedly accurate, are based on the pedaling of an unknown person, of unknown ability. We don't even know if they were sitting or standing! It's also unknown how much better the subject might be if they pedaled properly. The wattage they are producing is that of a fairly strong pro at LT. If they are not a such a pro, then they are producing wattage far exceeding their normal output, and it would be normal for their pedaling style to deteriorate. Mine probably would too, though I'm fairly good at 200 watts.

PurpleK

I've used them all, spd most of the time. My bike is currently outfitted with the same Shimano pedal Machka suggested, a combination of spd on one side and a flat platform on the other. Next week, these pedals will join about three sets of spd pedals in a box reserved for components that I don't use anymore but which are too nice to discard. I'm going back to toe clips.

I have used toe clips for my last couple of tours and found them to be more agreeable than clipless. For me, they're easier to flip and slide into when accelerating from a stop. I don't have to "search for the click." I haven't noticed a significant efficiency difference between clipless and toe clips. I can still cycle in stiff soled cycling shoes during the day, but I can ride out for an evening's entertainment in shoes more comfortable and appropriate for the occasion and still have the toe clip to keep my foot properly positioned on the pedal. Toe clips permit me to ride without installing cleats into the stiff-soled cycling shoes, so now I can walk through museums, businesses, B&Bs or homes without the fear of scratching the floor or the "grinding" sound which can happen even with the recessed cleat.

I have had both a toe clip and the cleat on a shoe to break during rides. It was much easier to pedal with a broken toe clip than with a shoe that wouldn't clip into the clipless pedal.

Freewheeler

That is a joke....right? What is your other foot doing?

Carbonfiberboy 

Only a joke to those who can't pedal. Sorry, dude. I can lift my whole spin bike off the floor in spin class too, just for jollies, not for exercise. Cycling is classified as a non-technical sport, but there is an element of technique to it. For example, the trick when hill sprinting is to keep both wheels on the ground. If one wheelies, one loses steering, lightening the other end loses traction, so weight and torque distribution have to be just so. It's my specialty. I don't have the VO2max to keep up with the real climbers. Imagine how fast you could sprint if you could nearly double the force you apply to the pedals. Go out and practice. I've taught many people to sprint. Relax your lower leg and foot on the backstroke and pull up on the heelcup with a powerful contraction of the hamstring. Good Mornings or straight legged deadlifts are good for the hams, though pedaling is better.

And yes, toe clips are just about as good, especially after your rat-trap pedal wears grooves in the bottom of your shoes so you don't pull out any more. The biggest difference is that clipless is safer and warmer. I only use double-sided SPDs for tandeming and touring so I never have to fuss with the pedal - just come down with the foot and it's in. Scary otherwise - Stoker would beat me up if I kept blowing her first power stroke.

gubaguba

There are definitely advantages to being clipped into, onto your pedals. If there was not then there would be no need for anyone to use them. They have been in use for better part of a century so I will leave it at that. That said modern clipless are used today for the same reason people no longer tie skis to their feet with leather straps. So if you crashed years ago with a bike securely strapped to your feet it stayed that way and tore tendons broke ankles and all sorts of nasty things. Clip less pedals will disengage allowing you to separate from your bike and thus reducing injury. This can be a very positive thing. Yes I speak from the point of experience.

TimeTravel_0

...thats if you happen to crash in just the right way to clip-out. I know I've fallen over and not clipped-out and ended up tangled up just as if I were in clips/straps.

people use foot retention because they like the way it feels...and they think it significantly improves their cycling. whether or not this improvement is real or imagined is up for debate.

I personally have gone "free" and am enjoying nice platforms. maybe im slower (I dont think I am), but I certainly enjoy the ride more and enjoy the simplicity of wearing whatever shoes/boots/flip-flops I want...just like I did when I was a kid.

Carbonfiberboy 

Right on. Many, many years ago I commuted to work in Seattle along 15th NW, a busy street with traffic right to the sidewalk. One day as I rode about 6" from the curb, a car brushed me and I touched the curb and went down at about 20 mph - headfirst into a telephone pole, bike still strapped to my feet, and helmetless as well. It took a while before I could see anything, so a bit scary, but I'll never forget that feeling of hitting the pole, hands on bars, feet in pedals, the whole contraption turned just right so my head hit the pole first. Bike was fine. I was fine - after a few minutes I could see and ride, so I went on into work. Not that much blood, really. I suppose I must have burned off some of that speed somehow before I hit the pole, or I'd not be here, though I had no road rash. No one wore helmets in those days. They were unknown.

My left pedal I'd strap to properly, strap tucked into buckle. The right one, I'd reach down and tighten it up, but not thread the strap, so I could easily reach down and slack it off for a stop. No way were my feet coming out! Riding in traffic was fun. I could out-accelerate cars for about the first 50', quite an advantage. It was fun being young, strong, and crazy. I learned to hill sprint in downtown Seattle traffic. Had a full-Campy Legnano. Wish I had it back.

jtgotsjets

Carbonfiberboy, I'm sorry, but you're just wrong. While I don't doubt that pulling on the upstroke can help at times, all the science points to the fact that in practice, nobody does this during normal riding. Normal people still apply downward pressure on the upstroke and the pros are good enough that they can basically keep their foot out of the way during the upstroke. Maybe you've discovered some crazy upstroke nonsense, but I didn't see you in the last Tour, so I'm just going to assume that what will make the pros go real fast will probably make me go pretty fast too.

Saying you know what's going on with your legs better than an instrument designed specifically to tell you what's going on with your legs is just as useful as saying you know you were riding your bike at least 88mph on your last ride because you can just feel what your legs are doing, man.
I mean, I know the Sun orbits the Earth because, duh, I see it go up over there, it goes down over there.... How difficult is all this astrophysics stuff anyway?

In any case, I'm with Grant Petersen. For touring and 95% of all other bike related activities, platforms are good.
If you're riding fixed, racing or just like having your feet strapped down (as you clearly do—although you're probably not transferring much power to your tires if you're lifting the rear wheel from your massive upstrokes) clips or clipless work.

staehpj1

I have to say that Carbonboy's observations are probably better than the test data for the specific things he is observing since they are not what the tests were focusing on. Folks seem to want to make the assumption that no one ever pulls up on the pedals because the test didn't observe it. Further they are implying that it proves that a retention system does not promote increased efficiency.

I think those are poor assumptions for the following reasons:

1. The test does not attempt to judge the value of clipless
2. The test in no way tries to compare clipless with no retention
3. The test in no way analyzes anything other than a normal spin, so using a different technique to get over the top of a hill or manage an especially steep climb are outside the realm of the test

Bacciagalupe

Sorry, but that is exactly what the tests were focusing on. Again: They are using pedals that detect the application of forces applied to the pedal. The pedals record the precise direction of the forces applied in 360º; the amount of force; where in the pedal stroke the force is applied; even where, on the pedal itself, the force is applied. It provides instantaneous cadence information at a much higher sample rate than a standard cadence meter.

Also, there are dozens of parameters that human beings simply cannot evaluate in a remotely accurate manner based on subjective measures. Cadence, speed, acceleration, elevation, duration and distance traveled, power applied to the drivetrain, heart rate, aerobic vs anaerobic efforts -- none of these can be measured accurately without mechanical assistance. On what basis, then, is "direction and amount of force applied to the pedal" any different?

From what I can tell, CFB isn't using power or cadence meters, he's just guessing, a subjective process that is heavily influenced by his own expectations. For example, he asserts that he's applying an even amount of power on both the downstroke and upstroke. However, legs are not massless; each leg is 10-15% of your body's mass. So for a 175lb individual, when seated that could easily mean that on the downstroke gravity is pulling 5-10 lbs down, and on the upstroke you need to lift an additional 5-10 lbs. When standing, these effects due to gravity will be significantly greater. To apply equal amounts of force to the drivetrain on both up and down strokes, you'd actually have to supply more force on the upstroke, especially when standing. I guess this just didn't make it to his diagram somehow.


OK, let's put it this way.

Pruitt heads up a sports medicine and training facility in Boulder, CO. He's been using force-measuring pedals since 1996. He's worked with elite riders such as Olympic track sprinters (who cycle at up to 130rpm) and Team Saxo Bank. Separately, Metrigear (bought this week by Garmin, btw) is working on its own force-measuring pedal system. They have a broad and deep sample pool.

So why exactly aren't they confirming the hypothesis that cyclists provide usable force to the drivetrain on the upstroke?


Incorrect.

This is not a single specific test that was run once and that's it. They've used the force-measuring pedals on a large pool of cyclists, ranging from track to road to off-road, for years. They've done standing vs sitting, flats vs climbs, you name it and I'm reasonably certain they've done it.


They are making no such claims. I am the one saying that, when you look at the data and consider the touring context, that developing a smooth stroke is most likely far more important than clipping in.

Or, to put it another way: Let's say that clipping in does somehow make you more efficient, and on a typical day you save 2 minutes on the climbs. You then spend another 2 minutes per day switching and dealing with shoes, and now need to carry 2 sets of footwear instead of 1. Is clipless still worth it? If you prefer the ride feel of clipless or toe clips, sure. If you don't, or prefer convenience over a tiny bit of efficiency, then no.

Carbonfiberboy 

But not at a higher sample rate than the human ear. The humm of the rollers is at least a good as Pruitt's instrumentation. I'd like to note that Pruitt states that most of the time, force is applied tangentially to the pedaling circle. That's the same thing I'm saying.

Really. If you want to know me, you have to ride with me. I have so much crap on my bar tops there's hardly room for my hands, though cadence and HR are the only things I watch. I don't have a power meter, but I ride with a fellow my weight who does, so I know my approximate output under various conditions, plus I didn't have to buy it.

I do assert that I can apply an even amount of power on upstroke and down, but only out of the saddle and only while sprinting, so for about 10 seconds or so. So your point about the rider's weight is well made and is the reason that if I'm not careful, I'll pull the back wheel up off the road when sprinting uphill. I think I've already mentioned that . . . Sprinting on the flat requires a greater emphasis on rpms than uphill, because you're spinning out your big gear. It's very difficult for me to pull up when standing at high rpm. Perhaps the pros are more coordinated, I don't know. Either sitting or standing, I can apply a considerable percentage of the total force on the upstroke, but usually only for a time frame of about a minute and at rpms of 90 or less. In any case, it's a tiny percentage of total pedaling time and not worth discussing except to refute the assertion that no one can do it.

The torque diagram I posted shows my normal effort when seated. You are misrepresenting what I said and showed. I assume you just didn't look at the graph carefully. I show a distinct positive downward pressure on the pedal on the upstroke, exactly like you and Pruitt hold should be the case. However, I also show strong tangential forces on the crankarm at TDC and BDC and for quite a few degrees on either side of those points. This is the real weak point of platforms: not that you can't pull up, but rather than you can't push forward or pull back.

Because he's trying to dispel illusions that some people have. If you read him carefully, you'll see he is not actually making the categorical statements that you are.


But they don't publish every test, do they?

It's just harder, if not impossible, to get smooth on platforms. That's the whole point of clips and clipless. Referring back to the graph you posted, it's impossible not to notice the power falls to zero at TDC and BDC with each pedal and that's the reason that the very sensitive cadence graph shows those variations. The power line is obviously cooked. You can't have those variations in cadence without identical variations in power.

IMO, it's not a tiny bit of efficiency. You ride 400k in under 15 hrs. ET with platform pedals and we'll talk. And besides being over 60, I'm not a fast rider. The fast boys came in under 12 hrs.

All that said, there's nothing wrong with platform pedals. I rode platforms until I got my first road bike at 17, did a zillion miles on platforms, another zillion with clips, didn't go clipless until I was 50. That's just about choices. Facts are another matter.

I invite the lurkers here to look at my posted graph carefully, then go out and try to duplicate those forces as well as they can with their clips or clipless pedals. You'll see immediately what I'm talking about. Coaches tell their cyclists doing high cadence drills to try to feel air under their feet throughout the pedal stroke - to pedal only with the uppers, not with the soles. You should feel the centrifugal force (tangential force, really) of a fast, smooth pedal stroke trying to rip your shoes off the pedals.

Another good thing to practice is climbing, say, a 6% grade at very low rpms, say 50. Except don't move your upper body at all. You'll see that you have to apply force exactly as I show in order to do that. And not only that, but it's comfortable. Well, as comfortable as that sort of thing is likely to be. Better than just pushing down, anyway. The touring application is obvious: we all run out of gears when it gets steep enough. You keep from walking by keeping a constant torque on the bottom bracket.

Bacciagalupe

I probably shouldn't respond, after all this is not a contest of attrition. Ahh, what the heck.

And just to repeat, I'm not disagreeing with your recommended methods, just some of the underlying assumptions.


I've realized there is a discrepancy between how Pruitt and Metrigear use the term "tangential" in this context, so I'm going to avoid using that term for the moment.

Both Pruitt and Metrigear recognize that it is only at the 3:00 position when all of the pedaling force goes into pushing the bike forward. As you push further down, more of the energy winds up bending the spindle in a direction that does not contribute to moving the bike forward. By the time you hit "bottom dead center," and for the entire upstroke, none of the force you are applying winds up pushing the bike forward.


OK then. Since you recognize that these devices are better measurements than subjective evaluations of effort, are you really asserting that both Pruitt and Metrigear, having independently used their different devices on numerous subjects, are just dead wrong?


OK, let's assume that I misunderstood part of your position. It still isn't the case that you are providing 100% even torque during the rotations. You have a spike of useful power at the 3:00 position (which pushes the bike forward), followed by lots of power that just bends the spindle (which is wasted), followed by a near-total drop-off of power as you just try to get your foot out of the way. So it's spike-spike-spike-spike-spike etc which, like a 2-cylinder engine, winds up producing a consistent power output. (This was the point of the Metrigear chart I posted; and yes, of course the average is spread over time, that's what an average is; otherwise it would say "sum of power.")

This is even more pronounced when standing. Perouse https://www.metrigear.com/2010/03/19/is-your/ for a few diagrams of standing vs sitting.


You have, but again your methodology simply is not strong enough determine that this is due to a massive application of power on the upstroke, rather than some other aspect at work. E.g. pro road race sprinters go from somewhere around 25-30mph while seated to 40-45mph standing in a matter of seconds, and afaik they don't pull their back wheels off the ground. (They'd almost certainly lose speed and crash if they did.)


As I said in my last post, there are certain elements that are purely my own conclusions drawn from the data and applied to a touring context -- specifically platforms vs clips for touring. I have not seen anything from any of these researchers on this specific topic -- nor am I making particularly strong statements on that specific aspect.

But, this is precisely what Pruitt says in the article. "The Best Cyclists Don’t Produce Power When They Pull Up on the Backstroke: As mentioned earlier, force-measuring pedals show us that no cyclists, not even track pursuiters who are capable of silky-smooth pedal strokes at 130 rpm, really exert upward force when the pedal is coming up from dead bottom center."

Sounds like a categorical assertion to me. Am I missing something?


Are you asking for a challenge?!?

Heh. I will freely admit that I don't know exactly how much efficiency is involved -- but, unfortunately, neither do you. For either of us to make such a claim, we'd need multiple tests with multiple riders, loaded and unloaded, using power meters. That probably won't happen outside of an academic context. However, based on the evidence, you simply do not double your power when you clip in.

Second, 400k in 15 hours is not a tour. That's a brevet. Tours are multiple days with plenty of rest; sometimes with luggage, sometimes with a SAG van. And as I tried to suggest, if you are the "hammer all day type," then yes you'll most likely prefer clips. If you are the "I don't want to fuss with cleats while I'm stopping at this restaurant," I'm gonna say that convenience and comfort are more important than sheer performance.

Carbonfiberboy 

Ah, we're getting closer to understanding each other.

I'm disagreeing with this assumption of yours. Let's suppose we don't push down or pull up at all. Suppose we only push forward at the top and pull back at the bottom? What pushes the bike forward then, if "none of the force you are applying winds up pushing the bike forward?" It's really quite simple and only involves a little muscular control. One simply stops pushing down just before the bottom of the stroke. Anyone who can pedal at a 130 cadence without bouncing knows this. After that, one starts pulling back, then a little after BDC starts pulling up with a continued contraction of the hamstring. But if you watch your leg while you're pedaling, you'll see the ham contraction becomes ineffective very quickly, which transfers most of the work to the relatively small psoas or hip flexor, which if well trained and strong can take most but not all of the weight off the pedal. One can work the psoas harder for a short time but it tires quickly, being small. Hence we normally leave a little weight on the pedal on the upstroke.

Well, if they say that no cyclist under any condition applies upward force to the pedal, then I would so assert.

Not only is this more pronounced while standing, it is only then that this occurs, if one is adept at pedaling. Almost everyone here who has toured with clipless pedals has come upon the situation where they have no longer been able to turn the cranks while seated in their lowest gear. Say 20% or greater grade. Ordinarily, a roadie with will come out of the saddle when the cranks get hard to turn. However, our tourer has shifted into such a low gear that, when standing, with every downstroke the bike surges forward, then almost completely stops when the pedals are vertical, only to surge at the next stroke. At this point we get off and walk. This is reductio ad absurdem of course, but it is true. So we see that this spike-spike-spike, like a 2-cylinder engine, is exactly what I am trying to avoid. That wastes an incredible amount of energy. Why not pedal smoothly with no power variation during the pedal stroke, as is shown by the graph I posted, where the power line is not the average, but in fact is the instantaneous sum of the two pedals?

I don't know the cyclist whose output is shown in the graphs at that link. Garbage in, garbage out.

As I said earlier, I am unable to pull up on the backstroke at high rpms. I don't know if pros can. It would be interesting, though not useful, to know.

Yes. He's making an incorrect categorical assertion, which is so foolish on the face of it as to make his other assertions also open to question. Ever ride Powercranks? It's impossible to ride them without pulling up on the backstroke. Yet many pros and committed amateurs use them in training. If Pruitt were right, it would also be impossible to pedal one-legged while maintaining a taut chain. I.e., Pruitt is simply wrong in this assertion. What Pruitt means to say is that typical riders, in typical riding situations, do not pull up on the upstroke. This is true, but it does not mean that in an atypical situation no rider pulls up. The mention of track cyclists is rather funny, because the ability to pull up decreases with rpm due to the weak psoas.

The best video I know of this phenomena is the Armstrong/Pantani duel on Ventoux.
https://www.youtube.com/watch?v=6q38Gyjv4EE
It's obvious that during Armstrong's initial attack he is pulling up viciously on the backstroke while standing. Later, one can see them both doing it while standing. While seated, much of the time they are certainly pulling up during the first 90° of the upstroke. In fact, it's this very video that got me experimenting with it. I'll never forget the sensation of the group disappearing the first time I tried it on a ride. I have acquired some tiny fame for this, in fact there is a local hill named after me.

I'm saying that anyone can do this, it's just the learning how. That's why I'm so insistent about this posting: I want to pass on what little I've learned in my decades of riding.

No, of course you don't double your 20 minute power - that's aerobically determined. But you definitely can increase your endurance by spreading the load among your leg muscles, and you definitely can increase your 1 minute and shorter power, especially at cadences of 100 or lower.

Another thing: I haven't been able to increase my momentary TT power particularly, as I'm unable to execute from the aerobars since the psoas is already contracted. Possibly longer legged riders can, since the proportion of crankarm to leg length decreases with leg length.

It would be fun to ride with you. You ever ride any SIR brevets? I very much enjoy the social aspects of brevet riding.

PurpleK

Mother of God.....Am I in physics class?

pasopia

Ok, as a side note, one of the main benefits I notice from riding with clipless pedals is the really stiff sole that comes with the mountain bike shoes I use in conjunction with them. Stiff shoes are waaay more comfortable to ride in for me, and they at least seem noticeably more efficient. If I ride for more than 10 miles or so in soft soled shoes my feet start to hurt.

Off the bike I find stiff shoes really uncomfortable, I prefer something like a pair of vans. So ignoring the benefits or being stuck to the pedal, I would still want different types of shoes for riding and walking. If I'm going to use a stiff shoe for riding only, it may as well be for clipless pedals. That being said I really like being clipped in when I ride.