Re: Factors affecting speed?

In article <[EMAIL PROTECTED]>, 
[EMAIL PROTECTED] says...
> On 03 Dec 2003 14:51:43 GMT, [EMAIL PROTECTED] (Pbwalther) wrote:
> 
> >>The other component I didn't think about is the friction in the chain
> >>in the deraileur and sprockets. This may have even a greater
> >>improvment and may have decreased my time by 10 seconds per mile.
> >
> >That IS peculiar.  I recall seeing a Scientific American article on the physics
> >of bicycling quite a few years back and they said that friction losses in
> >cycling were very small at something less then 1% of the energy expenditure. 
> >These losses were so small that the authors did not think that improving the
> >friction losses on a well maintained bike would have any measurable affect on
> >performance.
> >
> >  Now, that does not mean that you did not see an improvement?  Maybe it was
> >because your bike was now quiet and you felt confident enough to bear down
> >some.  Who knows?  But you chain would have had to have been in almost
> >inconceivalby bad shape to have affected your time that much.  Of course, I
> >have seen some might strange things so maybe your chain was in that bad of
> >shape.  I suppose anything is possible.    
> 
> Well, I posted my thoughts b/c I wanted to provoke discusstion, but
> didn't think it would be this controversial! ;-)
> 
> But I swear to you, my times were extremely stable prior to taking the
> bike in for a new back tire, and adjustment to the front (which might
> have been rubbing a very little bit on the brake pads-had it adjusted
> once, already). When I got home I sprayed WD-40 on the chain and
> sprockets and deraileur, then took a ride. My time improved by two
> minutes, over a rolling hilly river trail of 4 miles from 18:32 (prev.
> day and average over a month) to 16:15, the very next day.
> 
> I've continued to get times in the 16 minute range for the past 8
> rides, with ease. Go figure... ;-)

If your chain was really bad, it might have some effect, but pumping 
up your tires, putting on a new one (higher pressure one?), and fixing 
a rubbing brake would probably have a greater effect.

-- 
Dave Kerber
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