I do not see where the cyclists gearing is listed, I see cadence, but not comparable gearing.

It took me over a month of riding them to get about 2/3's of the way adjusted, I just picked up a set of the road bike so now I will be training exclusively on them. The subjects in the study had no break in period.

I cant see how the authors can compare wattage unless they display cadence AND gearing.

Also, isn't 225 watts kind of high for a non-cyclist? Makes me wonder.

This paper does not represent my experiences with the Rotors.

http://www.rotorbike.com/eng/tests.htm

Nor mine, happily.

Couldn't get the .pdf file to launch, so I can't tell much about the study's methodology, or who conducted and funded it. But the assertion of "no power difference" based on a test with 'untrained cyclists' who are managing to put out 225 watts (!) also strikes me as inherently quizzical.

PS: if it's a scientific fact that there's "no power difference", please don't tell Guido (who can no doubt kick all our butts on the bike), as the fact that he's so wrongheaded in his success will really bum him out. Also, does this mean I have to give back this year's wins, PR's, and age-group course records? :-(

try this:

http://www.timetrial.org/pdf/santella.pdf

Thanks, Gary. Am printing it and will read it in the morning.

Skimmed the abstract, and its Conclusion reads as follows: "Although more research is needed, especially with trained riders, the Rotor system might improve delta efficiency during endurance cycling. Other performance determinants (VO2 max, maximal power output) do not seem to be changed compared with the conventional system".

Why would V02 max be expected to change -- in just two tests, only 24 hours apart? This is a physiological parameter the subject brings with him/her. And isn't it average (sustainable) power output, not maximal (momentary) power output that's relevant here?

Under (test) Subjects it not only indicates that none were experienced cyclists, but goes on to say that "no subject had ridden on a bicycle (with the Rotor or conventional system) or cycle-ergometer during the 2 months before testing" Must have been quite a trick finding subjects like that in a cycling hotbed like Spain!

Skipped to the study's final sentence, which reads: "It would be interesting to conduct a similar study with elite cyclists".

Yes, it would. Or even average Joes who'd put a leg across a saddle at least once during the previous two months. :-) Would also be interesting to do a time series test, rather than a single set of one-time Rotor/conventional tests on untrained individuals.

Guess I should suspend further judgement until I read it, but initial impressions... Off to bed.

I thought the study was well performed (in view of Rotors claim of immediate power improvement from "elimination" of the dead spots) but I am not sure I trust the results (or I don't understand them).

Many of the previous comments are by people who clearly didn't read the study. This was a ramped power study and these non cyclists couldn't get ABOVE 225 watts on average. They were clearly non-cyclists. Further, this was done on an ergometer so gearing is unimportant.

I guess I don't understand the concept of delta efficiency. There were no significant differences between all the measured physiolgical variables like HR and VO2 at the various wattages. If HR and VO2 don't change significantly at any given wattage I don't understand how efficiency changed. Further, the degree of the efficiency changes is not consistent with the physiolgical changes. They report an efficiency change of from 21 to 23% (as I understand it) but in a soon to be published study on PowerCranks (I have seen the galleys) that degree of efficiency change (in cyclists) was associated with significant changes in VO2 and an average HR change (drop) of 15 bpm.

So, something is funny here and I am not sure what it is.

Frank

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Frank,
An original Ironman and the Inventor of PowerCranks

so far, all the articles I read on physiology explain that efficiency is very hard to measure and that until something better is used to measure efficiency,
efficiency is measured as watts for a given % of Vo2max or speed for a given % of Vo2max

so if using some tools like PC, RC or others, you
can for some watts use less vo2max then you have improved your efficiency.

Correct. However, in this study I didn't see the drops in VO2 (HR corresponds well to VO2 and the drops in HR weren't there either) so where did the supposed improvements in efficiency come from? That is my problem in interpreting the study.

Frank

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Frank,
An original Ironman and the Inventor of PowerCranks

The chamelion wrote: "BTW, I assume that the 15 bpm drop in HR you mentioned as resulting from the use of Powercranks reflects the results of a training study? That's much too big a change to occur acutely, given that gross (I assume gross) efficiency only changed by a couple of percent. If indeed these results were from a training study, what controls were employed to be certain that the changes were due to the use of Powercranks, vs. simply the effects of training per se? "

Rather than answer this I think I will wait until the study is published. There were controls (another matched group doing the same thing on regular cranks) and the results were statistically significant. I am sure there will be additional (probably some heated - I especially look forward to AC's opinion/thoughts) discussion of the study once it is actually published.

If delta efficiency goes to the efficiency of muscle contraction then it would tend to "agree" with my supposition as to why RC's work. They slow the pedal speed on the down stroke to a more efficient muscle contraction speed. This "elimination of the dead spot" explanation is a bunch of hooey in my opinion.

Unfortunately, from a cycling perspective, it is power to the wheel that really means anything from a speed perspective such that gross efficiency is a better measurement in the real world. I suspect that delta efficiency has come into vogue as a "better" measurement of efficiency because improvements in gross efficiency are so hard to come by. Delta efficiency may be better at measuring small improvements from what I hear you saying.

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Frank,
An original Ironman and the Inventor of PowerCranks

The entire concept of this study is stupid. It is well emphasized by Rotor and various case studies that the Rotors need a lengthy adpatation time to realize their full advantage. We have done extensive measurements on a particular athlete over a 3 month period. Result is that when first switching to Rotors there is no immediate performance difference between Rotors and regular cranks. Some gains were noticed within a few days of riding regularly on the Rotors. Significant gains were noticed within a month, and after 3 months we are still seeing small gains in performance. There are lots and lots of testimonials out there that back up this finding.

I am still waiting for a scientific study that measures the performance of a group of bikers over at least a month of adaptation to the cranks.

Our case study is on our website:

www.fact-canada.com

Further to this stupid study:
It would make a lot more sense to take two groups of similar cyclists (experienced or inexperienced). Measure their initial performance parameters on regular cranks. Put one group on Rotors (test group and control group). Give them all the same training over a one month period. Then remeasure the performance parameters to see which group has made the greatest gains.

Herb wrote: "The entire concept of this study is stupid."

I disagree. It certainly was my impression that Rotor claimed immediate performance improvement in using the device. Some here even read this study as supporting that view and they certainly have, in other threads, made that claim. This study simply looks at that claim. It does nothing to prove or disprove the worth of the device if there is an adaption period. If this study had been done on PowerCranks the PC group would have been lucky to finish the test and one might conclude that they hurt performance and that their only worth was as an expensive paperweight.

A negative result in a study does not make a study worthless. Studies must be taken as a part of the picture and put into context. The only worthless study is one that has inadequate controls for flawed data acquisition methods.

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Frank,
An original Ironman and the Inventor of PowerCranks

right.

I could show that swim drills are useless. Have someone change her/his technique and do a lot of drills for 3 weeks. then do a 1500m TT and times will likely be slower, because most swimmers know that when modifying your technique there is an adaptation phase where you actually get slower, because you are retraining your brain...

I guess to show that PC are useful, any study shorter than say 3 to 4 months on avg will show they hurt performance.

Francois wrote: "I guess to show that PC are useful, any study shorter than say 3 to 4 months on avg will show they hurt performance."

I think it depends on how the study is designed. I think you can show benefit for PC's in a shorter period of time if the study doesn't require any endurance. I am sure you could show benefit if one were to look at running benefit and not cycling. The study that was done (that I refer to in previous posts) lasted for 3 months and I must say, I was surprised at the degree of improvement that was demonstrated for what I considered to be "minimal" amount of training.

Anyone involved in science should know (not all of them do, obviously) that study design is extremely important to being able to appropriately interpret the results of the study.

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Frank,
An original Ironman and the Inventor of PowerCranks