Re: Bicycle Quarterly Rolling Resistance Tests: No Surprises

On 30 Mar 2007 19:43:48 GMT, jobst.brandt@xxxxxxxxxxxxxxxxxx wrote:

Carl Fogel writes:

An important point to emphasize- so I will do it again in reply to
JH and MM's posts- is that the BQ tests prove that, for paved
roads such as used in the BQ tests, suspension losses ARE NOT a
factor. We know this because, all other things being similar, air
pressure is by far the major determinant of suspension
losses. Yet, changing the air pressure within an important range
did not change the times any more than one would have expected due
to their influence on rolling resistance alone, based on the IRC
tests. Just as Jobst has been saying all these years.

I think it would be more accurate to say the suspension losses were
small enough to be lost in the noise of the BQ test. I believe they
are there, but appear to be fairly small. Alan Morrison has been
testing tires on rollers with a power meter, and his data is posted
at the Bike Tech Review site. He also tried testing on a "rough"
roller... one that had a series of wires attached to the
surface. This lessened the effect of tire pressure on Crr, but up
to at least 140 psi there was no pressure where the resistance
started to increase. I had actually expected to see a clear
"optimum" at a lower pressure.

For those interested in the rough roller tests, here are Morrison's
smooth and rough roller data sets:

http://www.biketechreview.com/tires/AFM_tire_crr.htm

Search here for bumpy AND rollers to pull up links to some threads
about ALM's testing:

http://biketechreview.com/phpBB2/search.php?mode=results

I take it these folks don't want anyone to understand what they found
so they don't display it graphically, or is it there is too little
data to generate curves in which one could see trends. Those endless
columns of numbers are great at hiding what was found. Computers can
make short work of such stuff and display it in a useful way. Next
they'll display the stuff in binary format.

Jobst Brandt

Dear Jobst,

I'd like a graph, too, but here's the thread in Bike Tech Review:

http://biketechreview.com/phpBB2/viewtopic.php?t=1249&highlight=bumpy+rollers

I notice two things.

1) Those folks--curse them!--may well not need graphs. They discuss
the data in detail without needing to whip out the hand puppets for
explanations.

(I could easily dislike them as much as I dislike people who can
program in assembler without looking up the instructions.)

2) The tone of their moderated thread puts RBT to shame--nothing but
content, courtesy, and curiosity.

Cheers,

Carl Fogel
.

Relevant Pages

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