Spoke Tensiometer questions

Tim McNamara wrote in message ...
(Bikefixr) writes:

You've been building wheels for years. Why bother with a
tensiometer? Absolute tension is not important-eveness of tension
around the wheel IS important. If you measured the same wheel with 3
different tensiometers, you'll get 3 very different measures. So
which one is right?

Reminds me of the Chinese proverb: a man with a clock knows what
time it is; a man with two clocks is never sure.

In practice, it doesn't matter. What they are good for is draining
your wallet and for novice builders who don't have any "feel"
yet. It might help keep them out of trouble, but I doubt it.

Why so cynical? It is actually helpful for beginners to prevent gross
under- or over-tensioning without having to deform a rim in the
process.

In 20 yrs of wheelbuilding, I have never once seen an amateur wheel
I would ride on.

So you wouldn't ride one of Jobst's wheels?

Hell, I wouldn't have ridden MY first 20 wheels or so...

Presumably somebody did.

So I suggest that you lace up, tension up. Keep as true and round as
possible as you tension up, lube the nipple-rim interface
regularly. I use subjective feel and sound. A human ear can hear far
more subtle differences than the hand can feel. When they all feel
the same, sound the same, I do minor tweaks and it's ready to
roll. 8,000 pr later I've never had a wheel failure. I say keep
doin' what you're doin' and comfortable with and refine your touch.

While much of what you say is true- especially the sensitivity of
judging relative tension by plucking spokes and listening to the
pitch- for the average person building a few wheels for themselves
this sort of proficiency will never develop. I've built hundreds of
wheels, but I can't tell if they're adequately tensioned just by
plucking a spoke or squeezing them. They could be significantly
undertensioned and still sound or feel OK, depending on a number of
factors (wheel size, pattern, spoke gauge, etc).

Oddly enough, you don't recommend stress relieving, probably the
single most important step you can take for ensuring good service
life of the spokes.

Dear Tim,

It's curious how many people feel that there are
some things that man was never meant to measure
with anything but the seat of his pants, like spoke
tension.

Oddly enough, the stress-relief of spokes that you call
the single most important step may be one of these sacred
cows:

"The fatigue resistance of spokes was not tested for
lack of suitable equipment." ("The Bicycle Wheel," 2nd
edition, Part III, "Equations and Tests")

And the stress-strain graphs of the tests of actual
stainless steel spokes in that section (figure 69)
don't look at all like the stress-strain graph used
to explain elastic limits (figure 15). The curves
of the actual spoke tests just climb toward failure
without any intermediate drop at an elastic limit
(which I gather is the normal behavior of stainless
steel--it shows no elastic limit).

Perhaps the third edition addressed this?

To be honest, I can't see any objective
difference between checking tension by ear
(bikefixr's approach) and grabbing spoke pairs
and giving 'em a good squeeze to relieve tension
(current received wisdom on rec.bicycles.tech).

Are there any studies showing actual results for
these seat-of-the-pants approaches? That is,
someone showing his ear to be as good at measuring
tension as a high-quality tensiometer, or someone
showing measurable effects from spoke-squeezing?

Either method may work. Anyone who can tune a violin
can see the idea behind spoke-plucking, and a healthy
squeeze might relieve some kind of tension in a spoke
already under 200 to 500 lbs of tension.

I'm just curious if anyone has ever demonstrated
that either method works in a fashion that could be
presented and repeated in an engineering course.

Carl Fogel

(Carl Fogel) writes:

It's curious how many people feel that there are some things that
man was never meant to measure with anything but the seat of his
pants, like spoke tension.

Well, as I mentioned in the other thread, experience results in
perceptual learning. There's a biological limit to how fine-grained
perception can be (and even that can be overcome to a degree- for
example, vascular surgeons using visual magnifying equipment can make
tiny, accurate movements that would not be possible without
magnification).

Oddly enough, the stress-relief of spokes that you call the single
most important step may be one of these sacred cows:

"The fatigue resistance of spokes was not tested for lack of
suitable equipment." ("The Bicycle Wheel," 2nd edition, Part III,
"Equations and Tests")

And the stress-strain graphs of the tests of actual stainless steel
spokes in that section (figure 69) don't look at all like the
stress-strain graph used to explain elastic limits (figure 15). The
curves of the actual spoke tests just climb toward failure without
any intermediate drop at an elastic limit (which I gather is the
normal behavior of stainless steel--it shows no elastic limit).

Perhaps the third edition addressed this?

You'd have to ask Jobst, eh?

To be honest, I can't see any objective difference between checking
tension by ear (bikefixr's approach) and grabbing spoke pairs and
giving 'em a good squeeze to relieve tension (current received
wisdom on rec.bicycles.tech).

Oops, apples and oranges. Stress relieving is basically cold setting
the spokes to relieve residual stresses that remain in the metal from
the process of forming the elbow and head (as I understand it,
anyway). What bikefixr is talking about is judging spoke tension by
ear, which is unrelated to stress relieving.

Are there any studies showing actual results for these
seat-of-the-pants approaches? That is, someone showing his ear to be
as good at measuring tension as a high-quality tensiometer, or
someone showing measurable effects from spoke-squeezing?

This is not a scientific study by any means, but in my personal
experience I can hear differences in spoke tension that do not
register on my Wheelsmith tensiometer. The change in pitch caused by
changing tension on a wire is mathematically a very precise
relationship. It's the same as tuning a stringed instrument, in
whcih case again the ear is more sensitive than measuring the string
tension. I don't have any specific studies I can refer you to, this
is from my undegrad class in perception umpteen years ago. Come to
think of it, though, there was a thread on this a couple of years ago
and I had dug out my old textbooks to look up the sensitivy of the
ear to pitch changes.

Either method may work. Anyone who can tune a violin can see the
idea behind spoke-plucking, and a healthy squeeze might relieve some
kind of tension in a spoke already under 200 to 500 lbs of tension.

Again, apples and oranges.

I'm just curious if anyone has ever demonstrated that either method
works in a fashion that could be presented and repeated in an
engineering course.

You'd have to ask Jobst if his stress relieving technique causes a
high enough momentary increase in tension to cold set the spoke
material. But that's a different question than judging spoke tension
by pitch.

An anonymous bikefixr snipes:

You've been building wheels for years. Why bother with a
tensiometer? Absolute tension is not important-eveness of tension
around the wheel IS important.

That's an interesting concept. And how tight is right? I suspect
from what you say that you are unaware that wheel strength is a direct
function of spoke tension and that this should be as high as a rim
safely permits. That level of tension is not easily assessed by any
other means than a tensiometer. Maybe you have another method and
should let others know what it is. I have described a method to find
that upper safe limit but I don't propose to use it for successive
wheels once that tension has been determined.

If you measured the same wheel with 3 different tensiometers, you'll
get 3 very different measures. So which one is right?

That's not the point. The point is repeatability and protection from
over or under tensioning. That works with a completely uncalibrated
instrument. However, the correct tension must be determined at some
time. Even your' claimed difference in tensiometers is in my
experience not significant compared to guesses by people who as you
suggest, don't believe tension is important.

In practice, it doesn't matter. What they are good for is draining
your wallet and for novice builders who don;t have any "feel" yet.
It might help keep them out of trouble, but I doubt it.

I see that you think engineers and engineering incompetent to define
what a structure should be while mechanics who have been repeating the
same errors for many years are appropriate mentors. What gives you
this aversion to education and the scientific method?

In 20 yrs of wheelbuilding, I have never once seen an amateur wheel
I would ride on. Hell, I wouldn't have ridden MY first 20 wheels or
so...

That's not saying much for your understanding of wheels. I know many
people who have ridden their first wheels for many tens of thousand
miles. Not being bicycle mechanics did not stand in their way to
building good and durable wheels. It only takes reading ability, and
a bit of manual dexterity. I notice on occasion that bicycle shops
that sell a wheel building book do not read it themselves for the
reasons that you seem to express.

So I suggest that you lace up, tension up. Keep as true and
round as possible as you tension up, lube the nipple-rim interface
regularly. I use subjective feel and sound. A human ear can hear
far more subtle differences than the hand can feel. When they all
feel the same, sound the same, I do minor tweaks and it's ready to
roll. 8,000 pr later I've never had a wheel failure. I say keep
doin' what you're doin' and comfortable with and refine your touch.

That's a nice testimonial but not much in the way of how tight a wheel
should be for someone who hasn't built many wheels.

Jobst Brandt

Carl Fogel writes:

It's curious how many people feel that there are some things that
man was never meant to measure with anything but the seat of his
pants, like spoke tension.

Oddly enough, the stress-relief of spokes that you call the single
most important step may be one of these sacred cows:

"The fatigue resistance of spokes was not tested for lack of
suitable equipment." ("The Bicycle Wheel," 2nd edition, Part III,
"Equations and Tests")

Maybe instead of repeating this quote ominously, you might add what
you think you would gain from a fatigue test of a specific spoke in a
text about building wheels. The book has been in print a long time
and its fatigue values would even when new not reveal what spokes to
use for a given wheel. How do you propose testing spoke fatigue?

And the stress-strain graphs of the tests of actual stainless steel
spokes in that section (figure 69) don't look at all like the
stress-strain graph used to explain elastic limits (figure 15). The
curves of the actual spoke tests just climb toward failure without
any intermediate drop at an elastic limit (which I gather is the
normal behavior of stainless steel--it shows no elastic limit).

To what are you alluding? These are curves taken directly from a
tensile tester. The reason for their presence is that the long yield
elongation of the DT spoke shows its ductility and that it does not
strain harden in use because the wire has already been work hardened
to its highest value and is still ductile enough to be cold formed.

Perhaps the third edition addressed this?

I see you are piqued and keep needling, just as Wheelsmith did in his
review of the book many years ago, claiming the book was incomplete
and therefore more or less useless. It seems you are taking over his
position in that respect.

To be honest, I can't see any objective difference between checking
tension by ear (bikefixr's approach) and grabbing spoke pairs and
giving 'em a good squeeze to relieve tension (current received
wisdom on rec.bicycles.tech).

"Giving 'em a good squeeze" is not to relieve tension (it does not)
nor is using a tensiometer. You can delete the "to be honest" in you
chiding manner, it only suggests that what else you say without that
preface is untrue, or at least that you have not said all of the above
with fill candor.

Are there any studies showing actual results for these
seat-of-the-pants approaches? That is, someone showing his ear to be
as good at measuring tension as a high-quality tensiometer, or
someone showing measurable effects from spoke-squeezing?

The reason this is not so is that there are many spoke arrangements,
crossed, radial, interleaved or not and a great variety of rims and
number of spokes, but you knew that because it has all been here in
this forum before, something that you seem to be good at digging up
from Google when you think it might support your point of view. That
point of view remaining silent although obvious from many allusions.

Either method may work. Anyone who can tune a violin can see the
idea behind spoke-plucking, and a healthy squeeze might relieve some
kind of tension in a spoke already under 200 to 500 lbs of tension.

You don't need to list all the things that "may work" they being
myriad and little use to those reading this newsgroup. Your ploy of
raising and army of straw men to discredit proven methods and
confusing these with old wive's tales, is not doing us any favors,
especially when you occasionally claim ignorance of science as you
ramble on in plaintiff's attorney style.

I'm just curious if anyone has ever demonstrated that either method
works in a fashion that could be presented and repeated in an
engineering course.

Can you repeat the WHOLE question in plain English so it is evident
what it is you don't understand?

Jobst Brandt

wrote:
Carl Fogel writes:


It's curious how many people feel that there are some things that
man was never meant to measure with anything but the seat of his
pants, like spoke tension.


Oddly enough, the stress-relief of spokes that you call the single
most important step may be one of these sacred cows:


"The fatigue resistance of spokes was not tested for lack of
suitable equipment." ("The Bicycle Wheel," 2nd edition, Part III,
"Equations and Tests")


Maybe instead of repeating this quote ominously, you might add what
you think you would gain from a fatigue test of a specific spoke in a
text about building wheels. The book has been in print a long time
and its fatigue values would even when new not reveal what spokes to
use for a given wheel. How do you propose testing spoke fatigue?

to be fair jobst, i think some spoke fatigue testing would be a good
thing. if nothing else, it will give some comparative measures on
whether the different manufacturing methods and materials used by
wheelsmith, d.t., sapim, etc make any difference to their fatigue lives.



And the stress-strain graphs of the tests of actual stainless steel
spokes in that section (figure 69) don't look at all like the
stress-strain graph used to explain elastic limits (figure 15). The
curves of the actual spoke tests just climb toward failure without
any intermediate drop at an elastic limit (which I gather is the
normal behavior of stainless steel--it shows no elastic limit).


To what are you alluding? These are curves taken directly from a
tensile tester. The reason for their presence is that the long yield
elongation of the DT spoke shows its ductility and that it does not
strain harden in use because the wire has already been work hardened
to its highest value and is still ductile enough to be cold formed.

"shows its ductility and that it does not strain harden in use"??? your
graphs /do/ show a plastic deformation zone above the elastic yield
point, do they not? and that region continues to rise for stress for
some strain percentage before u.t.s.? that's continuing cold work
continuing to harden the material and consuming the last of the
materials ductility.

unless you have a precipitation hardening material, which spoke wire is
not afaik, the /only/ hardening is from cold work. there is no strain
aging. any continuing cold work [i.e. any plastic deformation, not
fatigue] continues to harden, unless you are at u.t.s. no spoke is at
uts - your own graphs prove that. "already work hardened to its highest
value" is directly contradictory to "still ductile enough to be cold
formed".



Perhaps the third edition addressed this?


I see you are piqued and keep needling, just as Wheelsmith did in his
review of the book many years ago, claiming the book was incomplete
and therefore more or less useless. It seems you are taking over his
position in that respect.


To be honest, I can't see any objective difference between checking
tension by ear (bikefixr's approach) and grabbing spoke pairs and
giving 'em a good squeeze to relieve tension (current received
wisdom on rec.bicycles.tech).


"Giving 'em a good squeeze" is not to relieve tension (it does not)
nor is using a tensiometer. You can delete the "to be honest" in you
chiding manner, it only suggests that what else you say without that
preface is untrue, or at least that you have not said all of the above
with fill candor.


Are there any studies showing actual results for these
seat-of-the-pants approaches? That is, someone showing his ear to be
as good at measuring tension as a high-quality tensiometer, or
someone showing measurable effects from spoke-squeezing?


The reason this is not so is that there are many spoke arrangements,
crossed, radial, interleaved or not and a great variety of rims and
number of spokes, but you knew that because it has all been here in
this forum before, something that you seem to be good at digging up
from Google when you think it might support your point of view. That
point of view remaining silent although obvious from many allusions.


Either method may work. Anyone who can tune a violin can see the
idea behind spoke-plucking, and a healthy squeeze might relieve some
kind of tension in a spoke already under 200 to 500 lbs of tension.


You don't need to list all the things that "may work" they being
myriad and little use to those reading this newsgroup. Your ploy of
raising and army of straw men to discredit proven methods and
confusing these with old wive's tales, is not doing us any favors,
especially when you occasionally claim ignorance of science as you
ramble on in plaintiff's attorney style.


I'm just curious if anyone has ever demonstrated that either method
works in a fashion that could be presented and repeated in an
engineering course.


Can you repeat the WHOLE question in plain English so it is evident
what it is you don't understand?

Jobst Brandt

wrote in message ...
Carl Fogel writes:

It's curious how many people feel that there are some things that
man was never meant to measure with anything but the seat of his
pants, like spoke tension.

Oddly enough, the stress-relief of spokes that you call the single
most important step may be one of these sacred cows:

"The fatigue resistance of spokes was not tested for lack of
suitable equipment." ("The Bicycle Wheel," 2nd edition, Part III,
"Equations and Tests")

Maybe instead of repeating this quote ominously, you might add what
you think you would gain from a fatigue test of a specific spoke in a
text about building wheels. The book has been in print a long time
and its fatigue values would even when new not reveal what spokes to
use for a given wheel. How do you propose testing spoke fatigue?

And the stress-strain graphs of the tests of actual stainless steel
spokes in that section (figure 69) don't look at all like the
stress-strain graph used to explain elastic limits (figure 15). The
curves of the actual spoke tests just climb toward failure without
any intermediate drop at an elastic limit (which I gather is the
normal behavior of stainless steel--it shows no elastic limit).

To what are you alluding? These are curves taken directly from a
tensile tester. The reason for their presence is that the long yield
elongation of the DT spoke shows its ductility and that it does not
strain harden in use because the wire has already been work hardened
to its highest value and is still ductile enough to be cold formed.

Perhaps the third edition addressed this?

I see you are piqued and keep needling, just as Wheelsmith did in his
review of the book many years ago, claiming the book was incomplete
and therefore more or less useless. It seems you are taking over his
position in that respect.

To be honest, I can't see any objective difference between checking
tension by ear (bikefixr's approach) and grabbing spoke pairs and
giving 'em a good squeeze to relieve tension (current received
wisdom on rec.bicycles.tech).

"Giving 'em a good squeeze" is not to relieve tension (it does not)
nor is using a tensiometer. You can delete the "to be honest" in you
chiding manner, it only suggests that what else you say without that
preface is untrue, or at least that you have not said all of the above
with fill candor.

Are there any studies showing actual results for these
seat-of-the-pants approaches? That is, someone showing his ear to be
as good at measuring tension as a high-quality tensiometer, or
someone showing measurable effects from spoke-squeezing?

The reason this is not so is that there are many spoke arrangements,
crossed, radial, interleaved or not and a great variety of rims and
number of spokes, but you knew that because it has all been here in
this forum before, something that you seem to be good at digging up
from Google when you think it might support your point of view. That
point of view remaining silent although obvious from many allusions.

Either method may work. Anyone who can tune a violin can see the
idea behind spoke-plucking, and a healthy squeeze might relieve some
kind of tension in a spoke already under 200 to 500 lbs of tension.

You don't need to list all the things that "may work" they being
myriad and little use to those reading this newsgroup. Your ploy of
raising and army of straw men to discredit proven methods and
confusing these with old wive's tales, is not doing us any favors,
especially when you occasionally claim ignorance of science as you
ramble on in plaintiff's attorney style.

I'm just curious if anyone has ever demonstrated that either method
works in a fashion that could be presented and repeated in an
engineering course.

Can you repeat the WHOLE question in plain English so it is evident
what it is you don't understand?

Jobst Brandt



Dear Jobst,

You seem to have replied at considerable length
to a question that you claim not to understand.

Since you didn't answer it, I almost believe you.

Carl Fogel