From: frank@molbio.cbs.umn.edu (Frank Williams)
Subject: Re: pedaling efficency
Organization: MBCC, Univ. of Minnesota
Date: Thu, 9 Apr 1992 06:02:21 GMT

It is with some trepidation that I write this, but I was in on the pedaling
efficiency debate and I think the "new" evidence presented deserves comment.
My recollection of the basic question of the thread is that it asked, "What
is the most efficient way to pedal, pull up or not?"

Here's hoping that we don't stir up any of the original acrimony.


In article <1992Apr7.193610.21143@ico.isc.com> bobb@ico.isc.com (Bob Bundy) writes:
>
>I have been following the thread on pedaling efficiency (I have forgotten
>the initial Subject name) and happened to note a relevant article in this
>month's Velo News.  I apologize if this has been posted before, as I am an 
>infrequent reader of this group and may have missed it.
>
>Lennard Zinnn has an article on finding an efficient bike position.
>He cites most of the commonly used formulas and describes the problems
>with each.  He also notes the oft-quoted advice of LeMond to pull up on
>the back of the pedal stroke.  Lennard, first of all, points out
>that this is probably not what LeMond does at all, given his foot 
>position at that point.  Furthermore, he cites a study by Dr. Edward
>Coyle at the University of Texas where it was found that the best time
>trialists pulled up less on the back stroke and delivered more
>peak power on the down stroke.

How were these studies controlled to address the question "If I try to
unweight my foot as I pedal, how does my power output and efficiency
change?"  Remember that a) the muscles that UNweight the pedals are
much less massive than the hip and knee extensors, and b) if these muscles
are active, they may help a top time trialist less than an average rider.
Does Dr. Coyle's study say that, among cyclists tested, the degree to
which a rider pulls back and up causes them to be better or worse time
trialists?  Do we know whether the athletes tested were trying to unweight
on the upstroke, and whether they were actually using the appropriate
muscles when it was their intention to do so?  Intramuscular electrodes
would hurt while pedaling!

>Because athletes are good at what they do, it doesn't mean that they
>understand how they do it.  (I cited several examples of athletes who
>give explanations that are contrary to the facts in a posting
>to this group a few months ago.)  

So the question I have is "Do the top racers THINK they unweight their
pedals?"  Lemond, among others, does.  I don't dispute that the intention
may result in a relatively small short-term gain in power.  The thread's
title, however, is Efficiency.  I have yet to see a shred of data that
relates power output to O2 consumption and measures this efficiency using
various pedaling styles.  I have maintained, on theoretical grounds, that
the greater the mass of muscle that can be recruited to pedal, the more
efficient that pedaling can be.  I do not dispute Jobst's observation that
limiting all of one's pedaling effort to a few muscles can saturate the
body's pulmonary capacity.  I think that this observation does not address
the question of long-term efficiency.  If you pedal using only 1/2 of the
available muscle, but do so at anaerobic threshold, will the work done
after 45 minutes equal the work done by all of the available muscle at
anaerobic threshold after 45 minutes?  I'm guessing that, for me and 
the many average riders like me, the answer is no.  And I would hasten to
add that top time trialists may actually be different for a myriad of
reasons (like they don't work days, they had different parents, etc.). 

>Further, other measurements have shown
>that top racers generate nearly all of their power during the down
>stroke.  Voluminous citations of advice from bicyclists and coaches
>aren't going to carry the day when it runs contrary to actual measurement
>and observation.  

I am as quick to eschew unsubstantiated lore as anyone I know, but on this
one, I remain unconvinced.  My personal experience is that, regardless of
cadence, when I catch myself simply stomping down, I can always speed up
by pedaling "round".  When I go out with the fast guys and am humbled into
sucking wheel, the only way to survive is to pedal "round".  Am I doing
what I think I'm doing?  Maybe not.  Am I doing what Lemond writes he thinks
he does?  I think so.  I've been wrong in worse company.  Still, the more we
know about the physiological parameters in question, the better we can
coach riders to attain their full potential.

>It looks like Jobst, the cantankerous old curmudgeon (did I get that
>right?), could be right after all.

Of course!  But lets leave personalities out of the debate. :-) 


Spin & Grin!

Frank Williams
frank@molbio.cbs.umn.edu