On Sat, 01 Jan 2005 19:55:46 -0600, A Muzi
<[email hidden]> wrote:
[snip]
Quoted message said:I, for one, cannot 'prove' it. But it is true.
Observation showed that even before The Book.
Our mid-seventies wheelbuilding rate shows $5 for 'wheel
build'* and $8 for 'pro build, oil nipples, stress wheel
twice'.
David Agger, our resident wheel master of the era,
recommended bringing the oiled nipples to as high a tension
as we could with a Surre spoke wrench, pressing the wheel
over one's thigh and flexing the wheel as if to 'potato
chip' it, then finishing the wheel by loosening nipples as
much as possible. A second pass over one's thigh and we were
effectively (the hard way) relieving the stresses and
seating the spoke heads.
A practical man's observation led to roughly the same
prescription as Jobst's more thorough work and I'm sure
others noticed these phenomena to some extent before he wrote.
After The Book we had a more clear understanding of that.
David empirically noticed that bringing high-tension spokes
to a momentarily ultra-high tension and then backing off the
tension slightly made a more durable wheel.
* In those days we built every wheel in house, even steel
rims with galvanzed spokes.
Dear Andrew,
I appreciate your comments, but step back for a moment and
look at what you're saying.
That you charged more for squeezing spokes does not show
that it made spokes last longer.
Nor does it show why the spokes lasted longer.
It just shows that you charged more for squeezing spokes.
(That Dave in good faith squeezed them twice illustrates the
kind of problem involved. According to the modern theory,
two squeezes are pointless--a single squeeze is supposed to
be enough to make spokes immortal.)
(That Dave in good faith believed that this merely improved
spoke life is another kind of problem. According to modern
theory often expressed here, the spokes should not merely
have lasted longer--they should have lasted forever. No
properly squeezed spoke should ever fail except in a crash,
or so we're told, while all unsqueezed spokes should fail
fairly soon--although how soon is never pinned down.)
(That Dave began building more durable wheels is quite
possible, but how do we tell what made them better? For one
thing, the spokes themselves were improving in quality. Your
good faith here is evident--you explain that Dave began to
back off the tension slightly after the stress relief--which
sounds like the overshoot-and-back-off method of avoiding
spoke windup. It's demonstrable that wheels go to hell when
spokes with windup unwind and lose tension, but because of
our expectations stress relief is getting all the credit
here.)
(That yet another Dave has appeared in rec.bicycles.tech is
just further confirmation of my darker and unrelated
suspicions.)
To put it another way, there was also probably a higher fee
back then for tying and soldering, too.
After all, people as experienced and sensible and practical
as Dave honestly believed in the now-vanished habit of tying
and soldering.
Without a clear set of records that show wheels identical in
build and use (except for the spoke squeezing), it's hard to
convince anyone that it works, much less whether it works by
relieving internal stresses or by improving the hub/spoke
junction or by other means. And since everyone convinced of
the value of spoke squeezing seems to squeeze all their
spokes, there's no contemporary unsqueezed control group.
It is in things that cannot be easily measured that we are
most likely to fool ourselves. (We may not be fooling
ourselves about spoke-squeezing having an effect--but how do
we tell if there is no real testing or data? And how do we
tell whether it works by relieving internal stress or by
seating the spoke-head better or by simply encouraging us to
be more careful and thorough with all the other steps?)
When we do something that we believe beforehand will improve
things, we usually notice a difference that seems quite
empirical and obvious--whether it's there or not. The harder
it is to verify, the more likely we are to believe in it.
It's not a question of intelligence or honesty. Reasonably
intelligent and well-trained doctors performing charity work
are forever re-discovering how easy it is for us to see
results that we expect to see.
Is there really an effect?
If so, is it the result of spoke squeezing, reducing spoke
windup, better quality steel in the spokes, improved spoke
design in terms of elbow angle and head formation, changes
in how the spoke is whomped into shape, or what?
If the result is due to spoke squeezing, how does it work?
By relieving internal stress, by forming a better hub hole,
or what?
It's a fascinating question, if only because we are so prone
to--well, if not jumping to conclusions, but often taking
surprisingly large steps on faith.
Carl Fogel
