Poor man's Powercranks? (PPC)

Fday

Because it gets you using more muscle mass, DUH!

Or, to ask you the alternative. Why unweight at all? Most people do unweight some you know, the only question is how much do they "pull up" some unweight more than others. Why not push the entire leg weight up with the pushing leg (make the "recovery" completely passive)? Where would be the benefit in that?

Or, if you accept some unweighting is optimal, how much is optimal? And, how did you reach that conclusion?

Frank

Fday

I agree that we get that potential energy back, regardless of how the leg gets to the top. However, it does make a difference if you use new muscles to do it rather than diverting energy from muscles that are trying to apply power to the wheel. Nothing prevents the rider from pushing just as hard as they do now just because they start unweighting more or completely.

Frank

Fday

Overkill??

Piotr

... because unweighing doesn't require special power training, just a little concentration and practice. The weight of one's leg is plenty resistance and the only resistance one needs. Unless one plans on using hip flexors to propel the bike, which has already been discussed elsewhere ad nauseum. Again, I'm just speaking from experience.

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Fday

If it only took a little concentration and practice you would think the pros would have figured out how to completely unweight a long time ago. They have not or did not, at least until PC's came along. There is a fairly extensive list of pros who have thought the PC's have added substantial benefit to their training program. Hardly believe you are better, techniquewise, than they are, but I guess it is possible.

If you have been able to get on a pair of PC's and ride them without much of a problem for an hour or so the first time, then you are doing it. If not (of if you have never tried a pair of PC's) then I think you think your "experience" is more than you think it is.

daveryanwyoming

Frank,
You need to brush up on your physics, we don't get any potential energy back by either pressing harder on the downstroke to raise the opposing crank or by lifting on the upstroke. In either scenario we expend energy from one leg or the other or a combination of both. The only conceivable discussion of potential energy relates to the vertical height of our feet throughout the pedal stroke but that energy differential is insignifigant compared to propelling our bikes and our mass into the wind and up hills.

Your point about sharing the load between different muscle groups has merit, but the total energy expenditure is the same unless you're actively resisting the upstroke. As to whether the slightly lower load on the downstroke resulting from actively raising the other crank is worth the effort, I'd defer to an exercise physiologist.... Like the guy who's questioning your assertions.


You realize this is a double edged sword?

Fday

Ugh, I have brushed up on my physics, at least the physics needed to understand this. Actually, the potential energy put into the leg on the upstroke is substantial because we are talking about lifting a leg that may weigh 20 lbs 14 inches. And when we compare the forces on the down stroke we would find that it is rare that the forces on the downstroke would much exceed 50 lbs such that almost half of the force on the downstroke may be coming from recovering potential energy put into the leg during "recovery". Most people look at those forces and think it has all come from pushing. It has not but it leads to a lot of confusion. So, I disagree, the amount of energy put into the leg on the upstroke is not insignificant, it is substantial, even in ordinary cyclists who have never trained on PC's. PC's simply make one increase the amount of unweighting from 80-90% to 100%.

Frank

And, I would agree that it wouldn't make much difference where the forces came from if the power remained the same except, the whole idea is to increase the power, by invoking more muscles into the stroke and to develop increased efficiencies. You can defer to Dr. Coggan if you choose, and you will be lead down the garden path of wrongness.

Dr. Coggan has yet to explain the following except to state he believes the results to be bogus. But, what if he is wrong? Two studies, the one by Luttrell showed an increase in cycling efficiency of 10% after 6 weeks of training with PC's. What this means in terms you might understand, in these cyclists they were riding at the same power at a HR 15 beats lower than they did 6 weeks before.

Another study showed a 11% increase in max power and a 15% increase in VO2 max, also in only 6 weeks. And we are getting anecdotal reports of increases in VO2 max of up to 30% in less than a year in trained cyclists. And more studies are coming down the pike. Something has to be able to explain these results. Of course, Coggan will ascribe it to placebo, or training effect, or poor study design, or anything other than what his bias says it cannot be.

Anyhow, the studies will eventually determine the truth or not. I look forward to seeing Dr. Coggan back track.

Piotr

Well, since there's still serious discussion as to whether the mentioned technique is even necessary, whether pros have better technique than me is of no consequence. I don't need to ride PC's for an hour because nobody races on PC's (I hope!). I sure know when I unweigh my own leg better than anyone else though .

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Fday

People actually do race on PC's, not many but some do and they do quite well. Because they do well, they keep doing it. Courtney Ogden had the fastest bike split at Ironman Canada last year racing on PC's. This actually has included criteriums, not just time-trials or triathlons.

ric_stern/RST

Again, if these trained cyclists are getting increases in VO2max of 30% why aren't we seeing the world of cycling being turned upside down? a 30% increase in VO2max would take a trained average cyclist to the top of the pile (e.g., something like top 5 or 10 in the TdF). Surely, Frank, you must have sold enough of your cranks to average cyclists by now for this to occur? Or you've not sold any cranks, or your fantastical claims are pure myth....

Ric

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n crowley

Why 14 inches, it's the knee that is being lifted and for me that's about 10 or 11 inches and it's the effective weight of a hinged leg that you are lifting.
From my own experience the most effective area of the unweighting technique is at the start when your leg is given that instant boost of upward force which kick starts the other leg into reflexive instant action of power application but then I am accustomed to pedaling without a dead spot area where instant takeover of power application is vital.

Fday

How do you know it is not when the current world RR and Olympic Champion trains on them and all three grand tour winners last year are known or we have been told have trained on them at least some? Why would you expect that someone of lower rank would leap frog the current Olympic Champion when he takes up a training device used by the Olympic Champion? So, maybe it isn't turning the world of cycling upside down when those at the top are already using them.

Besides, winning takes more than just having a high VO2 max, otherwise they would just measure VO2 max. I don't think there has ever been shown to be a great correlation between winning and VO2 max. I would expect to see a correlation between improving and improving VO2 max though.

The data regarding PowerCranks will speak for itself once more of it becomes available. You will, of course, be free to continue to ignore it should it conflict with your current bias.

Frank

Fday

You are right, it is the foot that is lifted about 14 inches (twice the length of the crank). You are right, the knee is lifted less, and the CG of the thigh is lifted even less, but that doesn't mean it doesn't take substantial energy to do so.

ric_stern/RST

we don't even know who the big Grand Tour winner is...

That said even if they did train on them, this would be proof that even if we accepted they worked (i.e., improved performance) it isn't by the magnitude you keep suggesting (30% VO2max, or 40% increase in sustainable power). That is, the difference between winning and not winning is very small, and that if they suddenly gained the 30, 40 or whatever daft % you want to come up with the margin they won by would be a huge difference to what it currently is (was).



VO2max is the rate limiting mechanism in endurance exercise. Considering these riders were professional prior to your supposed intervention (your cranks) they've had small changes in fitness not huge great big walloping 30/40% increases (else their VO2max would likely be >100 mL/kg/min, which is beyond current human limits).

Additionally, as it is thought that some pros undertake doping (etc) regimens which alter haematological parameters and gain < 10% and risk their livelihood (i.e., getting banned) it would make more sense for them to use the 30/40% increase from your cranks.

Of course, though, the latter doesn't happen. It's just a figment of Franks imagination and his crappy testing equipment. I suspect he sits at home or the office dreaming up daft numbers.




It would be more credible, perhaps, if you suggested realistic figures of improvement rather than the crack induced ones you currently come up with. If you said, here's a product that can increase your VO2max/LT/efficiency (or whatever) by 5% that number would be at least within the realms of reality (not sure i'd still believe it). 30 - 40%, you're having a laugh, do you really think we're that stupid? My feeling is that the 40% is as real as the triathlete you came up with who was going to break the Hour Record several years ago while using your wonder cranks.

In the meantime, i suggest ploughing your profits in to a rehab centre so that you can get you off the crack or whatever it is you must be smoking.

Ric

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