LBS, you should be ashamed.

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Originally posted by Carl Fogel

Let's imagine the same rider coasting down the same hill twice.

On the first run, tires pumped up to 120 psi produce a harsh, badly suspended ride.

On the second run, tires at 60 psi provide a smoother, better-suspended ride.

Which ride do we expect to be faster?


Carl Fogel

The PSI difference is a bit big here, but my experience is that the suppler you keep your body (is this english?) when you go down a hill, the faster you go. You keep more control, so you can react better and take curves faster. Cramping up because of the high speed results in less control.

The problem with your equation here that it doesn't just involve suspension, but also resistance. I don't think Sheldon's statement can't be tested like that.
 
Originally posted by Tuschinski
The PSI difference is a bit big here, but my experience is that the suppler you keep your body (is this english?) when you go down a hill, the faster you go. You keep more control, so you can react better and take curves faster. Cramping up because of the high speed results in less control.

The problem with your equation here that it doesn't just involve suspension, but also resistance. I don't think Sheldon's statement can't be tested like that.

Dear Tuschinski,

I agree with you and Sheldon that suspension
improves cornering, braking, and pedal-powered
acceleration, all of which depend on traction,
which is improved by suspension.

Putting your weight on the pedals with your
knees flexed suspends most of your mass
from a long pair of possibly triple hinges
(ankles, knees, hips), which is more supple
than the immobile ischial bones of the pelvis
pressing down on a narrow bicycle seat.

So putting your weight on the pedals and
letting your ankles, knees, and hips absorb
and damp some bumpiness will help keep the
tires on the road for cornering, braking, and
pedal-powered acceleration. (The last not
being likely to matter on pavement except
in our more extreme fantasies--few of us
can hope to break the rear tire loose on
pavement by stomping on the pedals, even
on a bumpy paved road.)

But this is suspension in the sense of two
mechanical actions, first a movement of
two parts of the mass of bicycle and rider
( the bike rising when it hits a bump while
your knees bend to absorb the shock, or
your knees extending when the bike falls
away after a bump) and then some damping
(no complicated hyrdaulics are needed, since
human joints aren't very springy).

But whether your "suspension" involves
a coil spring and a hydraulic damper, your
legs, or just soggier pneumatic tires, the
improved traction always comes at the cost
of increased inefficiency--it takes energy
to work suspension units, energy that
otherwise would increase the rate at
which I hurtle down a long, dull, straight
hill.

This is one reason that bikes with suspension
sometimes come with lock-outs. Going uphill
on pavement, riders stomping on the pedals
notice a pogo-stick or trampoline effect. The
bike moves up and down on the suspension,
wasting some of their effort. Disable the
suspension, move toward rigidity, and the
suspension losses vanish.

So I expect that for a straight downhill roll,
clutching your bicycle as tightly and rigidly
as possible would be faster than any
relaxed, jiggling posture suitable for
cornering and braking.

Let's go the other way. Imagine two
large spheres, both the same size,
each with a thick outer shell and
enough neutral ballast so that they
weigh the same.

One sphere has a rubber coating that
gives as it rolls down the hill, the most
primitive form of suspension possible.
It flexes somewhat and gives a smooth
roll.

The other sphere is steel. It bounces
harshly, compared to the rubber sphere
of the same mass and size.

Which reaches the bottom of the
hill first?

Carl Fogel
 
Carl Fogel wrote: -snip, what?-
> Time to look for rhymes for silver, purple, and orange. Hmmm . . . honey, loyal, and boot, if I
> see things as Peter does, through a crossword puzzle darkly.

One's been done. Ogden Nash rhymed purple with maple syrple

--
Andrew Muzi www.yellowjersey.org Open every day since 1 April, 1971
 
"Facit indignatio versum." - Decimus Junius Juvenal On 6 Dec 2003 18:04:30 -0800,
[email protected] (Carl Fogel) wrote:

>Time to look for rhymes for silver, purple, and orange. Hmmm . . . honey, loyal, and boot, if I see
>things as Peter does, through a crossword puzzle darkly.

You're stumped to find a rhyme for orange? Here's not the place to whine nor whinge.

-------------------------------
John Dacey Business Cycles, Miami, Florida http://www.businesscycles.com Now in our twenty-first
year. Our catalog of track equipment: eighth year online
-------------------------------
 
A Muzi <[email protected]> wrote in message news:<[email protected]>...
> Carl Fogel wrote: -snip, what?-
> > Time to look for rhymes for silver, purple, and orange. Hmmm . . . honey, loyal, and boot, if I
> > see things as Peter does, through a crossword puzzle darkly.
>
> One's been done. Ogden Nash rhymed purple with maple syrple

Dear Andrew,

Others abide our question. Lord Byron, Ogden Nash, and Dr. Seuss are free.

What does silver mean that rhymes with honey? "Loyal" rhymes with "royal" purple. Orange is a color
and a what, to boot?

Matthew Arnold
 
A Muzi <[email protected]> wrote in message news:<[email protected]>...
> Carl Fogel wrote: -snip, what?-
> > Time to look for rhymes for silver, purple, and orange. Hmmm . . . honey, loyal, and boot, if I
> > see things as Peter does, through a crossword puzzle darkly.
>
> One's been done. Ogden Nash rhymed purple with maple syrple

In the spirit of "Reflections on Icebreaking," I will hereby commit the rest of my life to
developing a mixed drink called the "maple syrple."
 
well, mr.wizard said try this one... the point being that subtracting a few cubic inches of barn
door lets the door move through maine a helluva lot faster than prior then the designer gets worked
up about this, sees a few cents to be saved as well as going faster and wheee off we go!!!! plant a
seed, get a revolution-Sam J.?
 
[email protected] (g.daniels) wrote in message news:<[email protected]>...

[snip]

> plant a seed, get a revolution-Sam J.?

Dear Gene,

No, probably not uttered by the famous curmudgeon and self-described harmless drudge. Here's Dr. J's
take on the American Revolution:

These antipatriotick prejudices are the abortions of folly impregnated by faction, which, being
produced against the standing order of nature, have not strength sufficient for long life. They are
born only to scream and perish, and leave those to contempt or detestation, whose kindness was
employed to nurse them into mischief.

--"Taxation No Tyranny: An Answer to the Resolutions and Address of the American Congress by
Samuel Johnson"

Carl Fogel
 
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