Comparison test done PC vs Regular cranks

Triathlon Forum
188

Well, I would have used Figure 5 as that evidence. the Group 2 (good) cyclists clearly keep more (albeit small) “forward pressure” on the pedals during “recovery” than the Group one (elite) cyclists. That is my definition of “circular pedaling”, keeping forward pressure on the pedals the entire circle. Since we all learn how to pedal unattached to the pedals we are forced to maintain some backpressure on the pedals for the majority of the “recovery” when we pedal on platform pedals.

I thought you were using that data to “prove” that it is better to stomp than to “spin” or “pedal in circles”. How is it that the “good” group came to “spin” better than the “elite” group or why did the “elite” group stop spinning as well, assuming they transitioned through this period. Or, did these “elites” never pass through this phase (no proof) and spinning is bad if you want to become elite (no proof in this study but possible explanation). This last explanation seems to be what you are saying but it is pure conjecture as there is no evidence to support that conclusion.

Frank

189

Hum, this is an interesting post. please comment on my previous remarks. After all your model also showed that the pedal force from 180 - 360 degrees had a net torque of 0. Come on you must be able to explain what the effect to the forces required were leveled across the entire rotation.

If only positive torque is being applied during 180 degrees of the rotation, then how does this affect the RMS power output? What does the this say about the power applied during that time as compared to the RMS power output?

Actually, I think you do know the answer. You just chose to ignore this especially since you are smart enough to provide the answer to my question.

190

Mr. slow,

The problem is it is easier ignore than answer questions that force the academic to confront their biases. Keep holding their feet to the fire and they either have to leave or will eventually come around. It is like going from the world is flat to the world is round or the universe is all dark matter. It is hard for most to do but if the evidence for the current best theory is inconsistent, then another theory must be true. It is the scientific method.

191

over 200 replies. This one thread passed more than 1 percent of the entire forum, by my count, a long time ago.

Frank

193

Sure, I would be glad to clarify. Which part of the my original post do you want clarified?

My end question is really simple. Power measurements that we are discussing are in fact average (RMS) ratings or average ratings. You stated that Mr. Coyles researched showed that during 180 - 360 degrees of rotation zero net torque was applied. We then have torque applied during only half of the time. What amount of power is required during 50% of the time as compared to a steady torque application throughout the entire rotation?

195

not a pc’er wrote “Unfortunately, our muscles and joints are such that that is an impossible goal.”

You think it is impossible. I think, with the help of PC’s it is possible, at least to a certain degree. I guess I would have to ask you why you think it is impossible.

Frank

196

Not a PCer wrote: Assuming these tests are done on a trainer with low resistance, you really need to work on your spin. 44 mph in a 53x13 is only 138 rpm - maximal theoretical cadence is > 200 rpm, and most cyclist can spin up to 150-180 rpm before topping out.

No, this is a fluid resistance trainer, not a low resistance one such as rollers. I don’t know what my maximum rpms are, I do know that I can go about 130 on the rollers (on regular cranks) before I start bouncing around…very bad thing to do on rollers! I would agree with you that I would need to work on my maximum rpms…IF I were a road racer. I’m not. I’m a triathlete, max rpms aren’t very important to triathletes.

197

Not a PCer wrote: The group 1 subjects did 96.6% of the work during a pedal cycle during the downstroke, whereas in the group 2 subjects, this percentage was 90.1%. This is, of course, only for the one leg that was measured, but it is reasonable to assume that the unmeasured leg was approximately the same.

I was evaluated by Jim Obrien, a fitter, coach, dishwasher, whatever-it-takes-to-get-the-athlete-competitive in bicycling local guru. He said my pedal stroke was smoother than 90% of the cyclists he’s ever had pedalling in his shop. This includes George Hincapie, Pat McCallion, and Chris Harkey. (The latter fellows are top amature Time Trialist and Road Racers…think Chris held a 24 hour TT record, or just missed it, at Lowe’s Motor Speedway, I think Pat won a Nationals race in California last summer.) The point is, Mr. Obrien has seen and worked with some top quality riders. He said that my average of 108 rpm’s was probably “artificially” too high. It’s just where I always felt most comfortable, so I assumed it was the best rpm for me to ride.

Low, and behold! With Mr. Obrien’s direction, I found out I am MUCH faster at rpm’s in the mid 80’s via a couple of years of timed flat time trials the local bike club holds. Later, I also found out that my spin scans showed very equal curves under them, so, it was reasonable to assume that both legs would measure the same power output curves.

WRONG! I found out that I was attenuating my left leg tendency to push down very abruptly and hard by resisting that left leg drive with my rising right leg. Suddenly, my 90% smoother stroke had a major flaw exposed…certainly I was smooth, but I wasn’t as powerful as I could be, because I was having to waste left leg power; controlling it by resisting with my right leg. I didn’t know this until I had pressure plates put under EACH foot. (Although the guy that put the pressure plates under each foot suspected this problem when he observed my pedal stroke.)

You cannot correctly assume that one leg’s power curve is essentially the same as the other leg’s power curve. They must be measured independently.

The first time I rode with PC’s, this flaw showed up in about 15 seconds. It’s easy to notice when you know what you are looking for. It really can be a good tool to uncover inefficiencies like the one I had practiced, and unwittingly ingrained, for years.

198

Talon! You had a pre PC pressure plate analysis done? Wow, what would it take to get another one done 6 months or so from now. I will pay for it (if it isn’t way out of line).

Frank

199

The good news is: it was free! My son, an engineering student, rigged it up for me. At first, we thought we had a bad sensor. We changed sensors. Same curves. We changed cables. Same curves. We switched pressure plates from one side to the other. Same curves.

The bad news is: we didn’t save any hard copies. It was just a result of a father and son with nothing better to do but discuss the father’s nutty triathlon training methods one day on the way to the lab. We did this testing just on a lark. He was interested in seeing what he could rig up. I was interested in seeing what a smooth (HAHA) pedal stroke looked like. Boy was I surprised! And disappointed.

I really didn’t know what to do with the knowledge. I tried to pedal better, but didn’t really know what the results would be. I wish I could say that this is one of the reasons I ordered PCs in the first place. But, I really wasn’t thinking about it when I ordered them. I just knew I would like to have “true” smooth stroke, not an artificially smooth stroke.

PC’s didn’t give me a chance to think about the pedal inefficiency. They just correct it, as long as I am on them. I don’t know how much I have improved on regular cranks. It would be very interesting to keep a track of it. I’ll see if we can get back in there. He got it a bit of trouble for the sweat I laid down in his lab last time, we might have to be sneaky.

201

I found out that I was attenuating my left leg tendency to push down very abruptly and hard by resisting that left leg drive with my rising right leg.
Since most cyclists don’t demonstate such severe eccentricities in pedal action, is your experience with PCs truly representative of the norm?

I have no real way to assume what other people’s pedal actions are. It’s just that I assumed I had a very good pedal stroke. It was good enough that one experienced coach/fitter complimented me on it’s ability to make his resistance unit hum without the normal pitch changes. But, it was really not very efficient…it was just smooth.

I don’t think I would ever venture to say my experience with PCs represents the norm. In fact, on several occasions, I have stated that my results apply only to me. Good, bad, or indifferent. I’ve also stated several times that MY results are all I really care about. I have nothing to gain, or lose, by anything PowerCrank related…unless training (and maybe one day racing!) on them helps MY results. Really selfish, I know.

That said, trying to understand what can be learned from my experiences is important to me, simply because I have a curious mind. That’s why I keep asking these questions, and like getting other intelligent people’s ideas about the questions.

202

You would be surprised how many people hop on the cranks at expos and show such problems. Perhaps 5-10% and it seems evenly distributed between elite and beginners

Unfortunately, it is impossible to diagnose by using SRM or Spinscan when the cranks are fixed together. The only way to know is to isolate the cranks or use pressure plate pedals.

203

you will all agree that we don’t have nearly enough pointless bickering threads about powercranks, strawmen, and who has more siblings that work at top-notch hospitals on the first page, so as a public service i am trying to correct that …

hey, an idea for a new cable tv channel:
all powercranks all of the time … !

204

you will all agree that we don’t have nearly enough pointless bickering threads about powercranks, strawmen, and who has more siblings that work at top-notch hospitals on the first page, so as a public service i am trying to correct that …

hey, an idea for a new cable tv channel:
all powercranks all of the time … !
Wow, this thread goes back to 2003. The more things change the more they stay the same.

I found it interesting that in that thread there were plenty of PC’ers reporting positive results and putting in their two cents. Most of them have, seemingly, been shouted into submission as I am the only one still “discussing” these issues with the very same people who are “discussing” back.

Boy, brings back memories. What happened to The Committee anyhow? Does anyone know?