Re: Bicycle Quarterly Rolling Resistance Tests: No Surprises

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.

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.

So what's the upshot? I see the myriad numbers and cannot keep all
the values memorized to construct a comparative picture of what was
said. I don't understand that someone would curse graphs. What is
the argument against displaying all the data on one graph? I also
don't understand what the 1000Hz has to do with RR.

I suppose I could go back and put together a test report from previous
issues and pages of web articles, but I can imagine all this being
done by the researcher. For instance, I believe the wheel graphs in
"the Bicycle Wheel" do more for the understanding of rim deflections
than all the numeric data in the tables does. When the numbers are in
the computer, why not assemble it into a display that is useful to the
reader?

Jobst Brandt
.

Relevant Pages

  • Re: Bicycle Quarterly Rolling Resistance Tests: No Surprises
    ... changing the air pressure within an important range ... smooth and rough roller data sets: ... make short work of such stuff and display it in a useful way. ...
    (rec.bicycles.tech)
  • Re: DRS to lap cars
    ... that is indicated on the display. ... Pressure is force per unit area. ... Work or energy is force applied in a direction ... Now you can see how the units of power are protean, ...
    (rec.autos.sport.f1)
  • Re: Bicycle Quarterly Rolling Resistance Tests: No Surprises
    ... as used in the BQ tests, suspension losses ARE NOT a factor. ... this because, all other things being similar, air pressure is by far ... For those interested in the rough roller tests, ...
    (rec.bicycles.tech)
  • Lift of an airfoil
    ... One display that caught my eye was a small ... You could also adjust air speed. ... These pressure taps were each hooked to a simple manometer ... This display shows clearly that lift is due to a reduction of pressure ...
    (rec.models.rc.air)
  • Re: Bicycle Quarterly Rolling Resistance Tests: No Surprises
    ... as used in the BQ tests, suspension losses ARE NOT a factor. ... this because, all other things being similar, air pressure is by far ... testing tires on rollers with a powermeter, and his data is posted at ...
    (rec.bicycles.tech)