Originally Posted by
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.
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.
Originally Posted by
Bacciagalupe
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.
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.
Originally Posted by
Bacciagalupe
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?
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.
Originally Posted by
Bacciagalupe
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.
But they don't publish every test, do they?
Originally Posted by
Bacciagalupe
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.
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.
Originally Posted by
Bacciagalupe
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.
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.