Spoke tension meter
Ken
keep your wheels true under normal riding condtions. I have seen the Park
tm-1 I think is the model number and this seems like it is the most
economical one on the market. Is this something that the home diy'er should
have in his garage? I have a brand new wheel on the back (actually has about
200 miles on it) and that the spoke tension should be checked after a
certain number of break in miles ( I have read 100 miles is the number) But
to shell out a minimum of $50 for a tool that may or may not be used much is
a bit of a waste. Should spoke tension be checked with a meter on a regular
basis?
Ken
And are there any less expensive meters on the market?
--
For my real email address just remove "-dispose-trash"
More of my mind dribbles at my blog: http://mind-dribble.blogspot.com/
My personal website: http://kcm-home.tripod.com/
Art Harris
> I have a brand new wheel on the back (actually has about 200 miles > on it) and that the spoke tension should be checked after a
> certain number of break in miles ( I have read 100 miles is the number)
Wheels don't break in. If a wheel is built correctly, there is no need
to check tension at intervals. If they're poorly built (under
tensioned), spokes may loosen up when ridden.
Art Harris
App
tensiometers <snip>
I have the Park tool and the most useful thing it told me was that the
process defined in Jobst's book works. I took the tool to a set of
wheels I built with "the book" and check the tension - all spokes were
within +/- 10% (Park recommends +/- 20%).
Wheels I have built with the tensiometer are +/- 5%.
The least expensive meter is one you borrow or your ear (search this NG
for "spoke tension note tone").
I think Sheldon says proper tone is A flat or some such.
App
Jay Beattie
"App" <pete...@yahoo.com> wrote in message
news:1118347507....@g49g2000cwa.googlegroups.com...
The Park tool told me that I was building rear wheels at about
20% over recommended tension -- which I needed on standard rims
to keep them true at my weight. That is why I switched to OC
rims. The Park tool is so cheap, that even if it is not
absolutely necessary, it is a worthwhile novelty. Now, the chain
checker is a little spendy for my tastes -- and it always gives
me bad news. -- Jay Beattie.
P.S. Tone depends on spoke length and thickness, so there is no
single optimal tone.
Wasatch5k
What are OC rims?
nc
carl...@comcast.net
<wasa...@gmail.com> wrote:
Dear NC,
See "off center rims" threads in the archives.
Carl Fogel
Antti Salonen
> I was curious about these things, I know that spoke tension is important to
> keep your wheels true under normal riding condtions. I have seen the Park
> tm-1 I think is the model number and this seems like it is the most
> economical one on the market. Is this something that the home diy'er should
> have in his garage?
Especially for a beginner it can be difficult to tell when the spokes
are at proper tension, so IMHO, it's a very handy tool for anybody who
builds wheels.
I have the Park TM-1 and it's reasonably good. It doesn't give very
consistent readings, though, probably because there's some friction
between the handle and the body and the spring isn't all that stiff.
I think it's still good enough, because it doesn't really matter all
that much if the tensionmeter gives a reading of 95 or 105 kg for a
spoke that is actually at 100 kg.
I usually take a reading from a few spokes to tell when I've reached a
good overall level of tension. For individual spokes I equalise their
tension by tone.
> And are there any less expensive meters on the market?
I think the Park TM-1 is a fine investment at $50. I don't think there
are any cheaper alternatives, and better ones cost a LOT more.
-as
David Damerell
>I was curious about these things, I know that spoke tension is important to
>keep your wheels true under normal riding condtions. I have seen the Park
>tm-1 I think is the model number and this seems like it is the most
>economical one on the market.
It's also not desperately accurate; but if you're not in the sort of
situation where you're trying to build a heavily dished wheel on a weak
rim to carry heavy loads - caught between too high a tension on one side
and too low on another - it's good enough.
--
David Damerell <dame...@chiark.greenend.org.uk> Distortion Field!
Today is First Chedday, June - a public holiday.
Qui si parla Campagnolo
Ken wrote:
> I was curious about these things, I know that spoke tension is important to
> keep your wheels true under normal riding condtions. I have seen the Park
> tm-1 I think is the model number and this seems like it is the most
> economical one on the market. Is this something that the home diy'er should
> have in his garage? I have a brand new wheel on the back (actually has about
> 200 miles on it) and that the spoke tension should be checked after a
> certain number of break in miles ( I have read 100 miles is the number)
A tensionometer is a good idea and the Park tool is the least expensive
one. Tone and such 'may' work for even tension checking but for
absolute checking a meter is essential.
BUT, wheels don't 'break in'. The tension when built, if done
correxctly and stress relieved and all the wind up out of the spokes,
do NOT change when riding. Nothing streetches, nothing breaksin. If a
new wheel makes all sorts of noise when new, or the tension changes, it
was poorly built.
Qui si parla Campagnolo
A flat for what spoke gauge?...Spoke gauge makes the pitch different.
Unless you can play the piano or some crappola, tone for tension
doesn't work.
>
> App
Sheldon Brown
>>Wheels I have built with the tensiometer are +/- 5%.
>>
>>The least expensive meter is one you borrow or your ear (search this NG
>>for "spoke tension note tone").
>>
>>I think Sheldon says proper tone is A flat or some such.
Actually, I defer to my friend John Allen on this.
See: http://www.bikexprt.com/bicycle/tension.htm
Peter Chisholm asked:
> A flat for what spoke gauge?...Spoke gauge makes the pitch different.
It does for equal absolute tension. John's article is based on
tension/cross sectional area, and aims for a tension of about 1/3 the
yield stress of typical stainless spokes. For this the pitch is the
same, because the inertia of the mass of the spoke cancels out the
difference in absolute tension.
When he wrote that article, back in 1987, spoke failure was commonly the
limiting factor in how tight the spokes could be. Since then, rims have
been made lighter and weaker, so that now days the rim is often the weak
link, and lower spoke tensions are sometimes needed to avoid rim failure.
> Unless you can play the piano or some crappola, tone for tension
> doesn't work.
I don't play the piano or even the crappola, just takes normal hearing.
I've found it to work pretty well as a way to compare one spoke or one
wheel with another.
I own a couple of tensiometers, but I still plink the spokes to check
for evenness of tension. I do tend to use the tensiometer to judge when
the wheel is up to tension, but if I didn't have a tensiometer, I don't
believe I would miss it all that much. I was building wheels
successfully for decades before tensiometers became available.
Sheldon "A Poor Workman Blames His Tools" Brown
+--------------------------------------------------+
| For every complex problem, there is a solution |
| that is simple, neat, and wrong. |
| --H. L. Mencken |
+--------------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com
carl...@comcast.net
<capt...@sheldonbrown.com> wrote:
[sni--]
[Drat this dull key that won't cut text!]
[sni--]
[Press harder!]
[sni--]
[Oops--that's the Insert key, not the Del key . . .]
[SNIP!]
>Sheldon "A Poor Workman Blames His Tools" Brown
Dear Sheldon,
Well . . .
Carl "A Workman Is Only As Good As His Tools" Fogel
Zog The Undeniable
> I was curious about these things, I know that spoke tension is important to
> keep your wheels true under normal riding condtions. I have seen the Park
> tm-1 I think is the model number and this seems like it is the most
> economical one on the market. Is this something that the home diy'er should
> have in his garage? I have a brand new wheel on the back (actually has about
> 200 miles on it) and that the spoke tension should be checked after a
> certain number of break in miles ( I have read 100 miles is the number) But
> to shell out a minimum of $50 for a tool that may or may not be used much is
> a bit of a waste. Should spoke tension be checked with a meter on a regular
> basis?
It *is* a good idea to use one when building a wheel, but for the small
number of wheels built by most amateurs it's a difficult expense to justify.
Wheels are surprisingly tolerant to a poor build, or you'd see a lot
more collapsed ones out on the road (I've never seen a total wheel
failure, and only one broken spoke - on a machine built wheel).
Assuming the nipples were well-lubricated before building, when you find
the spokes are beginning to wind-up significantly, creaking and
"snapping" back into position, the wheel is probably tight enough. Do
Jobst's stress relieving thing with all your might, and if it stays true
you'll know you haven't overtensioned it either.
All your wheels will end up at a slightly different tension, but there's
a pretty big window of acceptability there. They'll probably still be
10 times as good as the ones my LBS does ;-)
carl...@comcast.net
<hroth...@yahoo.com> wrote:
[snip]
>Wheels are surprisingly tolerant to a poor build, or you'd see a lot
>more collapsed ones out on the road (I've never seen a total wheel
>failure, and only one broken spoke - on a machine built wheel).
^^^^^^^^^^^^^^^^^^^^^
[snip]
Dear Zog,
Interesting observation--not at all what the casual reader
of this newsgroup would expect.
Thanks,
Carl Fogel
Blair P. Houghton
>The least expensive meter is one you borrow or your ear (search this NG
>for "spoke tension note tone").
>
>I think Sheldon says proper tone is A flat or some such.
Which A flat?
--Blair
"Plink plink plink..."
Blair P. Houghton
>A flat for what spoke gauge?...Spoke gauge makes the pitch different.
>Unless you can play the piano or some crappola, tone for tension
>doesn't work.
Gauge, material density, shape, length, all perturb the tone
for the same tension.
If Sheldon said that, he's high, having us on, or talking about
the wheels on his favorite tourer.
--Blair
"Ha ha funny."
Blair P. Houghton
I'd just like to point out that a good workman blames his
tools when the tools are fucked up, or else he's not much
of a workman.
--Blair
"Damnable sense."
Jasper Janssen
A good workman knows his tools are fucked up before starting a project,
and doesn't try to use them to do things they can't do.
Jasper
Jasper Janssen
>On Fri, 10 Jun 2005 19:03:10 +0100, Zog The Undeniable
><hroth...@yahoo.com> wrote:
>
>[snip]
>
>>Wheels are surprisingly tolerant to a poor build, or you'd see a lot
>>more collapsed ones out on the road (I've never seen a total wheel
>>failure, and only one broken spoke - on a machine built wheel).
>Interesting observation--not at all what the casual reader
>of this newsgroup would expect.
Load on the wheels matters a lot. I weigh close to two regular riders, and
I break spokes on my (machine-built, three-speed hub, steel rim) wheels on
my commuter iron steed (which also has to hop the occasional low curb, of
course) on a regular basis. The very first wheel I ever built, for my
father who's not that heavy by a long stretch, broke spokes extremely
often due to overtension.
Jasper
Qui si parla Campagnolo
Sheldon Brown wrote:
>
> I don't play the piano or even the crappola, just takes normal hearing.
>
> I've found it to work pretty well as a way to compare one spoke or one
> wheel with another.
>
> I own a couple of tensiometers, but I still plink the spokes to check
> for evenness of tension. I do tend to use the tensiometer to judge when
> the wheel is up to tension, but if I didn't have a tensiometer, I don't
> believe I would miss it all that much. I was building wheels
> successfully for decades before tensiometers became available.
>
> Sheldon "A Poor Workman Blames His Tools" Brown
Gee, so do I. Tone to compare tension is something all of us old fart
wheelbuilders use. But I also use a DT dial tensionometer to check
actual tension to see if I am where I want to be. I think I could
probably tell also but when building 5-6 wheels in one day, hands
getting tired, different rims, the tensionometer is a good thing.
But the concept of plucking a spoke and then truing a wheel cuz it's a
few notes too low, that just makes me giggle, but I don't play anything
but the truing stand.
jobst....@stanfordalumni.org
It sounds so hokey with all these pseudonyms.
Zog The Undeniable
I wrote:
>>Wheels are surprisingly tolerant to a poor build, or you'd see a lot
>>more collapsed ones out on the road (I've never seen a total wheel
>>failure, and only one broken spoke - on a machine built wheel).
>
> ^^^^^^^^^^^^^^^^^^^^^
> Interesting observation--not at all what the casual reader
> of this newsgroup would expect.
If you look at some of the horrible wheels out there, yes it is
surprising. I think one helpful factor is that the cheapest wheels on
the $100 bikes usually have 36 spokes, and that's a structure that can
take a lot of abuse both in terms of a poor build, hard riding and lack
of maintenance [1].
To balance things up, I've seen a broken crank, a broken frame and
pretty much anything that can happen to a tyre (puncture, blow-off,
skidding right through the casing in one stop, slashed sidewalls,
leaving black trails on hot roads...)
[1] although a wheel with a good build needs no maintenance, unless the
rim wears through or you twist it in a storm drain :-(
Ken
<jobst....@stanfordalumni.org> wrote in message
news:ghFqe.471$p%3.3...@typhoon.sonic.net...
> Can't we just use the term: "Tensiometer"?
> It sounds so hokey with all these pseudonyms.
>
> Jobst....@stanfordalumni.org
Well I would have used this term, but i was not sure it was a the right
term, or something someone had made up.
Ken
carl...@comcast.net
Dear Ken,
Don't worry too much about it.
The level of fuss about "tensio(n)meter" serves as an
attentio(n)meter that measures how much attention is being
paid to what matters.
The more ill-natured fuss about it, the less attentio(n) is
being paid to the good-natured original questions and
replies.
A cheerful alternative is to add a space instead of removing
the "n"--google for "tension meter" and you'll find a
respectable number of manufacturers.
Or you can use other happy phrases, such as "tension gauge"
or "tension tester"--they work quite nicely.
Interestingly, the tension level in a thread tends to rise
in direct proportion to the number of snide comments. Oddly,
we are all too often astonished that sarcasm and insults
fail to win friends or influence people.
Carl Fogel
Bill Sornson
Dear Carl,
David Damnitall told me to tell you that you're just being Jobst's tool.
Nanny Bill
jobst....@stanfordalumni.org
>> Can't we just use the term: "Tensiometer"?
>> It sounds so hokey with all these pseudonyms.
> Well I would have used this term, but i was not sure it was a the
> right term, or something someone had made up.
Try:
John Dacey
>Don't worry too much about it.
>
>The level of fuss about "tensio(n)meter" serves as an
>attentio(n)meter that measures how much attention is being
>paid to what matters.
>
>The more ill-natured fuss about it, the less attentio(n) is
>being paid to the good-natured original questions and
>replies.
>
>A cheerful alternative is to add a space instead of removing
>the "n"--google for "tension meter" and you'll find a
>respectable number of manufacturers.
>
>Or you can use other happy phrases, such as "tension gauge"
>or "tension tester"--they work quite nicely.
>
>Interestingly, the tension level in a thread tends to rise
>in direct proportion to the number of snide comments. Oddly,
>we are all too often astonished that sarcasm and insults
>fail to win friends or influence people.
Jul: O Tensio, Tensio! wherefore art thou Tensio?
Ten: O! be some other name: What's in a name? that which we call a
gauge by any other name would spell conceit.
-------------------------------
John Dacey
Business Cycles, Miami, Florida
http://www.businesscycles.com
Since 1983
Our catalog of track equipment: online since 1996
-------------------------------
Sheldon Brown
> Gee, so do I. Tone to compare tension is something all of us old fart
> wheelbuilders use. But I also use a DT dial tensionometer to check
> actual tension to see if I am where I want to be. I think I could
> probably tell also but when building 5-6 wheels in one day, hands
> getting tired, different rims, the tensionometer is a good thing.
>
> But the concept of plucking a spoke and then truing a wheel cuz it's a
> few notes too low, that just makes me giggle, but I don't play anything
> but the truing stand.
I don't think you give yourself enough credit. If somebody brought you
a wheel and the spokes plunked "a few notes too low" I'm sure you could
tell that it was undertensioned without needing to throw a tensiometer
on it.
I don't understand why you keep bringing up the issue of whether
somebody knows how to play a musical instrument. This has _nothing_ to
do with the issue.
Sheldon "Not Tone Deaf" Brown
+--------------------------------------------+
| If you haven’t yet discovered the novels |
| of Neal Stephenson, don’t wait! |
| Start with Snow Crash or Quicksilver |
+--------------------------------------------+
carl...@comcast.net
<capt...@sheldonbrown.com> wrote:
>Quoth Peter Chisholm:
[snip]
>> But the concept of plucking a spoke and then truing a wheel cuz it's a
>> few notes too low, that just makes me giggle, but I don't play anything
>> but the truing stand.
>
>I don't think you give yourself enough credit. If somebody brought you
>a wheel and the spokes plunked "a few notes too low" I'm sure you could
>tell that it was undertensioned without needing to throw a tensiometer
>on it.
>
>I don't understand why you keep bringing up the issue of whether
>somebody knows how to play a musical instrument. This has _nothing_ to
>do with the issue.
>
>Sheldon "Not Tone Deaf" Brown
Dear Sheldon,
True, but I still enjoy a fantasy in which Harpo Brown
plucks a delightful Gilbert and Sullivan tune on a
mis-tensioned 36-string 700c-sharp wheel.
(Or a loom. Or a piano.)
Carl Fogel
Ken
"Sheldon Brown" <capt...@sheldonbrown.com> wrote in message
news:42AC7491...@sheldonbrown.com...
Quoth Peter Chisholm:
> Gee, so do I. Tone to compare tension is something all of us old fart
> wheelbuilders use. But I also use a DT dial tensionometer to check
> actual tension to see if I am where I want to be. I think I could
> probably tell also but when building 5-6 wheels in one day, hands
> getting tired, different rims, the tensionometer is a good thing.
>
> But the concept of plucking a spoke and then truing a wheel cuz it's a
> few notes too low, that just makes me giggle, but I don't play anything
> but the truing stand.
I don't think you give yourself enough credit. If somebody brought you
a wheel and the spokes plunked "a few notes too low" I'm sure you could
tell that it was undertensioned without needing to throw a tensiometer
on it.
I don't understand why you keep bringing up the issue of whether
somebody knows how to play a musical instrument. This has _nothing_ to
do with the issue.
Sheldon "Not Tone Deaf" Brown
I have noticed a lot of people posting about the "tone" that a spoke makes
when plucked. But myself being tone def, this seems like a very unlikely
method I would be able to use. I am thinking that if I am ever to "build" my
own wheels I will invest in a tensionometer.
Ken
Qui si parla Campagnolo
Sheldon Brown wrote:
>
> I don't think you give yourself enough credit. If somebody brought you
> a wheel and the spokes plunked "a few notes too low" I'm sure you could
> tell that it was undertensioned without needing to throw a tensiometer
> on it.
>
> I don't understand why you keep bringing up the issue of whether
> somebody knows how to play a musical instrument. This has _nothing_ to
> do with the issue.
>
I guess I equate playing an instrument with knowing something about
music scales and octaves, and C sharp and A flat, type stuff. I have
read some who have charts that say a 14g sp[oke at proper tension is
such and such note, and that is a giggle to me.
App
The right one - hell if I know, I never made the assertion, just
repeated it with attribution. And I use a tensiometer anyway. But I
did, before I got the tensiometer, use tone to help judge homogeneity
of spoke tension (but not absolute tension).
If you are really interested in the method behind this musical madness,
DAGS (in this NG, of course).
App "I'd rather hear A flat than get one"
Sheldon Brown
>>I don't understand why you keep bringing up the issue of whether
>>somebody knows how to play a musical instrument. This has _nothing_ to
>>do with the issue.
>>
Peter Chisholm wrote:
>
> I guess I equate playing an instrument with knowing something about
> music scales and octaves, and C sharp and A flat, type stuff.
That "type stuff" is what I learned in 7th grade music class at
Marblehead Junior High School. It's sad that many school systems have
discontinued teaching such basic stuff, material that any educated
person should know.
If you can hear well enough to enjoy music, you can hear well enough to
use this system.
http://bikexprt.com/bicycle/tension.htm contains a table of pitches with
a graphical representation of a piano keyboard so even if you don't know
your a# from your elbow, you can find the appropriate note.
> I have
> read some who have charts that say a 14g sp[oke at proper tension is
> such and such note, and that is a giggle to me.
Sorry if your education was deficient, but the physics of this is
clearly explained by John Allen at:
http://bikexprt.com/bicycle/pitcheqn.htm
Sheldon "Yes, I'm A High School Graduate" Brown
+--------------------------------------------+
| If it can't be expressed in figures, |
| it is not science; it is opinion. |
| --Robert A. Heinlein |
jobst....@stanfordalumni.org
>> I have read some who have charts that say a 14g spoke at proper
>> tension is such and such note, and that is a giggle to me.
> Sorry if your education was deficient, but the physics of this is
> clearly explained by John Allen at:
http://bikexprt.com/bicycle/pitcheqn.htm
Something doesn't add up here. The reference states:
# The cross-sectional area of the spoke and the mass per unit length m
# are exactly proportional to each other. Therefore, for two
# different strings or wires of equal length, one thick and another
# thin, the frequency is the same if the tension per unit of
# cross-sectional area is the same. One way to think of this is to
# imagine two identical spokes side by side, both of the same gauge
# and at the same tension. They vibrate at the same frequency. Now
# imagine lightly connecting them together all along their length.
# They still vibrate at the same frequency. Finally, imagine merging
# them into one, thicker spoke. It still vibrates at the same
# frequency.
Two spokes have twice the tensile load of one spoke. As an example,
guitar strings are wire wrapped to increase their mass for a lower
frequency.
see:
http://www.stringbusters.com/faq.html#Tension
Where:
# Sets of strings are gauged so that with standard guitar tuning they
# feel nearly equal in tension. String tension is obviously related
# to scale length and pitch but for any given guitar it is not the
# string gauge itself which is important but the mass of the string.
I didn't give this a lot of consideration until reading Allen's
explanation. Besides, tension of interleaved spokes are notoriously
difficult to assess by tone because they touch at partial length to
cause other resonances. I analyzed this with a frequency analyzer
when writing the book and found separating the principal frequency
difficult and unreliable.
However, listening whether spokes have a similar tone (higher or
lower) when plucked with a fingernail (sharp tone) is accurate in
comparing spokes in a well tensioned wheel and does not involve music.
There are other misleading items in Allen's website about spoke tension
as well. I would avoid citing that source.
Sheldon Brown
>>Sorry if your education was deficient, but the physics of this is
>>clearly explained by John Allen at:
>
>
> http://bikexprt.com/bicycle/pitcheqn.htm
Jobst Brandt replied:
> Something doesn't add up here. The reference states:
>
> # The cross-sectional area of the spoke and the mass per unit length m
> # are exactly proportional to each other. Therefore, for two
> # different strings or wires of equal length, one thick and another
> # thin, the frequency is the same if the tension per unit of
> # cross-sectional area is the same. One way to think of this is to
> # imagine two identical spokes side by side, both of the same gauge
> # and at the same tension. They vibrate at the same frequency. Now
> # imagine lightly connecting them together all along their length.
> # They still vibrate at the same frequency. Finally, imagine merging
> # them into one, thicker spoke. It still vibrates at the same
> # frequency.
>
> Two spokes have twice the tensile load of one spoke.
Yes, and they also have twice the mass of one spoke.
> As an example,
> guitar strings are wire wrapped to increase their mass for a lower
> frequency.
The wire wrapping is not under tension, so it's not analagous to a
simple strand, as with a bicycle spoke.
>
> see:
>
> http://www.stringbusters.com/faq.html#Tension
>
> Where:
>
> # Sets of strings are gauged so that with standard guitar tuning they
> # feel nearly equal in tension. String tension is obviously related
> # to scale length and pitch but for any given guitar it is not the
> # string gauge itself which is important but the mass of the string.
>
> I didn't give this a lot of consideration until reading Allen's
> explanation. Besides, tension of interleaved spokes are notoriously
> difficult to assess by tone because they touch at partial length to
> cause other resonances. I analyzed this with a frequency analyzer
> when writing the book and found separating the principal frequency
> difficult and unreliable.
The human ear/brain can hear things that are "difficult and unreliable"
to judge with a frequency analyzer.
> However, listening whether spokes have a similar tone (higher or
> lower) when plucked with a fingernail (sharp tone) is accurate in
> comparing spokes in a well tensioned wheel and does not involve music.
Right.
> There are other misleading items in Allen's website about spoke tension
> as well. I would avoid citing that source.
Could you be more specific? In addition to being a close friend, John
is an M.I.T. graduate in mechanical engineering, so his credibility is
pretty high with me.
Sheldon "Whom To Believe, M.I.T. Or Stanford?" Brown
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jobst....@stanfordalumni.org
>>> Sorry if your education was deficient, but the physics of this is
>>> clearly explained by John Allen at:
http://bikexprt.com/bicycle/pitcheqn.htm
>> Something doesn't add up here. The reference states:
>> # The cross-sectional area of the spoke and the mass per unit length m
>> # are exactly proportional to each other. Therefore, for two
>> # different strings or wires of equal length, one thick and another
>> # thin, the frequency is the same if the tension per unit of
>> # cross-sectional area is the same. One way to think of this is to
>> # imagine two identical spokes side by side, both of the same gauge
>> # and at the same tension. They vibrate at the same frequency. Now
>> # imagine lightly connecting them together all along their length.
>> # They still vibrate at the same frequency. Finally, imagine merging
>> # them into one, thicker spoke. It still vibrates at the same
>> # frequency.
>> Two spokes have twice the tensile load of one spoke.
> Yes, and they also have twice the mass of one spoke.
The point is that the example ignores that the two spokes with twice
the mass have twice the tension. In fact it is a sleight of hand with
now you see it, now you don't. The example demonstrates that the wire
thickness (aka mass) is a parameter in the resonance unlike what Allen
says.
>> As an example, guitar strings are wire wrapped to increase their
>> mass for a lower frequency.
> The wire wrapping is not under tension, so it's not analogous to a
> simple strand, as with a bicycle spoke.
The wire wrapping increases mass and changes the resonant frequency.
>> see:
>> http://www.stringbusters.com/faq.html#Tension
>> Where:
>> # Sets of strings are gauged so that with standard guitar tuning
>> # they feel nearly equal in tension. String tension is obviously
>> # related to scale length and pitch but for any given guitar it is
>> # not the string gauge itself which is important but the mass of
>> # the string.
NOTE: Wire mass affects tuning, and as the article states, all strings
have about the same tension but have their characteristic tone from
their mass, which in some instances is enhanced by wire wrap. Allen's
equation is bogus.
>> I didn't give this a lot of consideration until reading Allen's
>> explanation. Besides, tension of interleaved spokes are
>> notoriously difficult to assess by tone because they touch at
>> partial length to cause other resonances. I analyzed this with a
>> frequency analyzer when writing the book and found separating the
>> principal frequency difficult and unreliable.
> The human ear/brain can hear things that are "difficult and unreliable"
> to judge with a frequency analyzer.
I'm sorry for not expanding on that but we tested various tensions and
noted that the cross laced spokes gave a frequency that is a mix of the
crossing spokes. We could not easily distinguish which spoke was
causing the characteristic tone. We could hear differences but we
could not identify a correlation between that tone and the two
crossing spokes, one tighter the other looser.
>> However, listening whether spokes have a similar tone (higher or
>> lower) when plucked with a fingernail (sharp tone) is accurate in
>> comparing spokes in a well tensioned wheel and does not involve
>> music.
> Right.
>> There are other misleading items in Allen's website about spoke
>> tension as well. I would avoid citing that source.
> Could you be more specific? In addition to being a close friend,
> John is an M.I.T. graduate in mechanical engineering, so his
> credibility is pretty high with me.
He stated that pedaling standing substantially increases spoke
tension, something that comes up regularly here from the naysayers.
This is not true. The differences in tension are loss of tension of
the downward directed spokes not an increase in the upper spokes.
This all arises from the "hang from the top" spoke visualization. I
didn't go into detail to spare the readers the following invective
that comes from such concept.
jim beam
reality check:
1. wire stiffness affects tuning - that's why "heavy" wires are wrapped,
not solid - they remain more flexible.
2. the guy that neglects wire stiffness in his own tensiometer math
[page 119 of your book] is really not entitled to call anyone elses math
"bogus".
Paul Kopit
wrote:
>He stated that pedaling standing substantially increases spoke
>tension, something that comes up regularly here from the naysayers.
>This is not true. The differences in tension are loss of tension of
>the downward directed spokes not an increase in the upper spokes.
>This all arises from the "hang from the top" spoke visualization. I
>didn't go into detail to spare the readers the following invective
>that comes from such concept.
>
>Jobst....@stanfordalumni.org
I accept that twisting the hub via standing doesn't increase spoke
tension. Is this relative to building wheels with the trailing spokes
with heads outside the flange? Why do you recommend that orientation
of trailing spokes?
jim beam
> On Tue, 14 Jun 2005 02:16:52 GMT, jobst....@stanfordalumni.org
> wrote:
>
>
>>He stated that pedaling standing substantially increases spoke
>>tension, something that comes up regularly here from the naysayers.
>>This is not true. The differences in tension are loss of tension of
>>the downward directed spokes not an increase in the upper spokes.
>>This all arises from the "hang from the top" spoke visualization. I
>>didn't go into detail to spare the readers the following invective
>>that comes from such concept.
>>
>>Jobst....@stanfordalumni.org
>
>
> I accept that twisting the hub via standing doesn't increase spoke
> tension.
no, but pedalling standing does - because of the lateral loading.
lateral loading increases tension substantially. jobst seems to have a
massive blind spot in that regard.
jobst....@stanfordalumni.org
>> He stated that pedaling standing substantially increases spoke
>> tension, something that comes up regularly here from the naysayers.
>> This is not true. The differences in tension are loss of tension
>> of the downward directed spokes not an increase in the upper
>> spokes. This all arises from the "hang from the top" spoke
>> visualization. I didn't go into detail to spare the readers the
>> following invective that comes from such concept.
> I accept that twisting the hub via standing doesn't increase spoke
> tension.
Who said anything about twisting? This is an entirely lateral force
visualization from leaning the bicycle while climbing. Torque is not
involved in this concept.
> Is this relative to building wheels with the trailing spokes with
> heads outside the flange? Why do you recommend that orientation of
> trailing spokes?
If you know you read this in "the Bicycle Wheel" then you also read
why, and that it is a trivial difference, not to be worried about.
The reason is that the inbound pulling spokes become ever so slightly
tighter when pedaling and the pushing ones looser by the same amount.
Coming from the inside and crossing over the others means that the
spoke crossing (that is adjacent to the derailleur) is pulled away
from that interaction if clearance is low and might make a difference.
Jim Smith
> Paul Kopit wrote:
>> On Tue, 14 Jun 2005 02:16:52 GMT, jobst....@stanfordalumni.org
>> wrote:
>>
>>>He stated that pedaling standing substantially increases spoke
>>>tension, something that comes up regularly here from the naysayers.
>>>This is not true. The differences in tension are loss of tension of
>>>the downward directed spokes not an increase in the upper spokes.
>>>This all arises from the "hang from the top" spoke visualization. I
>>>didn't go into detail to spare the readers the following invective
>>>that comes from such concept.
>>>
>>>Jobst....@stanfordalumni.org
>> I accept that twisting the hub via standing doesn't increase spoke
>> tension.
>
> no, but pedalling standing does - because of the lateral
> loading. lateral loading increases tension substantially. jobst seems
> to have a massive blind spot in that regard.
Do you ever creep yourself out even a little bit with your stalking?
Just wondering.
carl...@comcast.net
Dear Jim,
Of more interest would be the obvious question how much does
a rider lean or tilt the bike from side to side when he
pedals while standing.
Some riders might tilt scarcely at all, others might roll
the bike like one of those inflatable clowns, but most are
probably in some range that I don't recall being mentioned
in this technical newsgroup.
If we knew how far over a typical front and rear wheel
tilted during actual stand-up riding, we could then ask how
much force a powerful rider is stomping into the pedal and
pulling up on the handlebar.
Then someone with a knack for physics could figure out what
the spokes actually do when the bicycle is tilted over (if
it does indeed tilt much) and a powerful rider is tromping
on the pedals.
I have a vague notion that many pros release their brakes on
climbs because otherwise the rims rub against the pads, but
this may be something else or somehow not related to spoke
tension.
I expect that it's a well-trodden question, but I never
heard of a physics question that suffered from being
re-explained or re-explored.
How far over do the bikes tilt when a pack of pros lurch up
onto the pedals and start sprinting uphill or toward the
finish line? One degree? Five? Ten? Twenty? Thirty?
Does the tilt and stomp affect the spoke tension?
I'm not even sure that this is what the "lateral load"
question is about, but I'm willing to learn.
Curiously,
Carl Fogel
Jim Smith
Fair enough. But sometines it is hard not to imagine certain posters
with one hand as they scan the posts of those with similar initials
for technical errors with the other, all under the watchfull eye of
their stuffed penguin at his perch atop the monitor.
As someone else pointed out, there is a film titled "Triplets of
Belleville" with excellent footage of Tour de France climers in
action. As a bonous, it also contains a demonstration of truing a
wheel by ear. Dynamiting a plate of frogs and settling down to watch
the DVD would be an excellent way to start your research.
jim beam
does it ever creep you out to have someone pose as an "expert" when
they're really not? do you fancy visiting a doctor like that? what
about a surgeon? how about flying in a plane designed by someone that
doesn't understand metal fatigue?
you can make a simple judgment on this scenario for yourself - do the
ping test. exert a lateral load on a wheel so the rim touches one brake
pad for example. pluck a spoke on that same side. notice the change of
pitch compared to when you're /not/ exerting that lateral load?
increase in pitch = increase in tension. that's fact. substantial
lateral load substantially increases tension. that's fact too. for the
"expert" to attempt avoidance of such plain, easily tested, irrefutable
evidence with this "hanging from the top" obfuscation is quite ridiculous.
Qui si parla Campagnolo
Sheldon Brown wrote:
e.
>
> Sorry if your education was deficient, but the physics of this is
> clearly explained by John Allen at:
I guess. I did play percussion instruments, so I know about tempo type
stuff but never knew music scales were in any school requirements.
Mostly DOD schools tho.
Joe Riel
> you can make a simple judgment on this scenario for yourself - do the
> ping test. exert a lateral load on a wheel so the rim touches one
> brake pad for example. pluck a spoke on that same side. notice the
> change of pitch compared to when you're /not/ exerting that lateral
> load?
> increase in pitch = increase in tension. that's fact.
> substantial lateral load substantially increases tension. that's fact
> too.
Both facts, however, they need to be connected. Back in April I
posted my simple test of the effect of lateral loading on spoke
tension, estimated via the change in tone. A change in a semitone (my
estimate of the maximum change due to pushing the rim sideways so that
it touches the pad) represents a change in tension of 4^(1/12) ~ 12%;
not insignificant but also not what I would consider "substantial".
On the road, however, thea rear wheel is not displaced by laterally
loading the rim at the brake, which minimizes the required force.
The forces involved may require substantial changes in spoke tension.
That has to be shown.
Joe
Jim Smith
> does it ever creep you out to have someone pose as an "expert" when
> they're really not? do you fancy visiting a doctor like that? what
> about a surgeon? how about flying in a plane designed by someone that
> doesn't understand metal fatigue?
OK. I guess I was underestimating Jobst Brandt's influence in the
bike world. Your use of the word "expert" also piqued a vague sense
that I had heard that he testifies as an expert witness in bike cases.
I suppose that seen in that light your relentless pursuit makes sense.
41
carl...@comcast.net wrote:
> I never
> heard of a physics question that suffered from being
> re-explained or re-explored.
Questions, having no nervous systems, are incapable of suffering. Not
so for the those answering them over and over again, nor for the
audience. The questioner though often does seem to take perverse
delight.
Dave Lehnen
<snip>
The tilt of a bike under a standing rider cannot be used to
determine lateral loading on the wheels, many previous posts to
the contrary. Only when a rider is coasting is this accurate, or
necessarily the dominant force. A standing rider can generate very
large dynamic forces, reacting against his own body mass and moment
of inertia. These forces alternate in direction, and averaged over
time, the bike and rider stay upright and traveling in a straight
line.
This analogy isn't perfect, but consider a person standing next to
and grasping a vertical post, the bottom of which is not fixed.
Statically, the person can lean in the opposite direction of the
post, while both are balanced, but the force is limited by how far
he can lean the post, and the mass properties of himself and the
post. However, if he violently shakes the post, the applied force
is limited only by his own strength.
As another example, consider a standing coasting rider, traveling
in a straight line, but leaning the bike to one side under his body.
The combined center of gravity is directly above the line between
the contact patches of the tires, but the rider is leaned, say,
slightly left, while the bike is leaned a lot right. In this
condition, the lateral loads on the wheels can be calculated in a
straightforward manner, with static analysis. Now consider the
rider, in this same position, bouncing on the pedals. The dynamic
forces, and the resulting lateral wheel loads, can be much higher
than in the static case.
Calculating peak lateral loads in the wheels of a sprinting rider
is not simple, it depends on a whole lot more than simply the
maximum lean angle bike reaches. My guess is that the peak loads
don't even coincide with the max angles, but are probably
earlier in the cycle.
Dave Lehnen
Sheldon Brown
To: Sheldon Brown <Capt...@sheldonbrown.com>
From: "John S. Allen" <jsa...@bikexprt.com>
Subject: Re: Spoke tension meter (rec.bicycles.tech
Cc: Jobst....@stanfordalumni.org
Following is my reply to Jobst Brandt's criticisms of my articles on
spoke tension, which Sheldon Brown forwarded to me. I am distressed by
Brandt's broad and nonspecific criticisms when, in fact, I agree with
almost everything he has to say about wheelbuilding, and I have long
used and cited his book, The Bicycle Wheel.
***************
Anyway, Brandt said:
... tension of interleaved spokes are notoriously
difficult to assess by tone because they touch at partial length to
cause other resonances. I analyzed this with a frequency analyzer
when writing the book and found separating the principal frequency
difficult and unreliable.
Sheldon Brown responded:
The human ear/brain can hear things that are "difficult and unreliable"
to judge with a frequency analyzer.
And I respond to this: Sheldon is accurate in describing hearing vs. the
frequency analyzer, though on the other hand, it is not practical to
determine the tension of crossed spokes individually when they are
plucked as a unit at the cross. See below.
Brandt, again:
However, listening whether spokes have a similar tone (higher or
lower) when plucked with a fingernail (sharp tone) is accurate in
comparing spokes in a well tensioned wheel and does not involve music.
There are other misleading items in Allen's website about spoke tension
as well. I would avoid citing that source.
In a later message, Brandt made one specific criticism, to which I
respond below. If he has others, let him be specific. One point I know
that he and I disagree on is the level of tension that is appropriate.
He has stated that he would raise tension until the rim begins to
distort -- but that criterion depends on the strength of the rim, and
particularly with heavy rims it can lead to overtight spokes -- a plague
with today's low spoke-count boutique wheels -- for my take on them, see
http://www.runride.com/symposium/tradition2.files/frame.htm --requires
Internet Explorer with vector graphics.
I judge tension with relation to the yield point of the spokes, using
musical pitch or a tensiometer. If the spokes are too heavy for the rim,
the rim will indeed distort, and either a stronger rim or lighter spokes
should be used.
I have never had one spoke break in any wheel I have built, except due
to damage by the chain. Even my tandem has never broken one spoke, in 25
years. It still has all the original Schwinn 13-14 gauge single-butted
galvanized spokes.
Brown again:
Could you be more specific? In addition to being a close friend, John
is an M.I.T. graduate in mechanical engineering, so his credibility is
pretty high with me.
Actually, electrical engineering. The introductory physics courses are
the same. More to the point, I took a course in musical acoustics,
including a unit on vibration of stretched wires.
Brandt also says:
NOTE: Wire mass affects tuning, and as the article states, all strings
have about the same tension but have their characteristic tone from
their mass, which in some instances is enhanced by wire wrap. Allen's
equation is bogus.
This is not "my equation" -- it is the classic equation for the
fundamental vibration frequency of stretched wires, lightly modified to
account for the wire stiffness. I have performed extensive testing of
the musical method against measurement using with a tensiometer, and
published the results in Human Power, #53, Spring 2002. The
correspondence between the results of the two techniques was as good as
could be expected considering the inaccuracy of measurement.
I'm sorry for not expanding on that but we tested various tensions and
noted that the cross laced spokes gave a frequency that is a mix of the
crossing spokes. We could not easily distinguish which spoke was
causing the characteristic tone. We could hear differences but we
could not identify a correlation between that tone and the two
crossing spokes, one tighter the other looser.
I agree with this, as I have repeatedly indicated, and so I don't
understand why Brandt criticizes me over it. In a well-built wheel, any
two crossed spokes are at nearly the same tension, and plucking them
together will produce a clean tone representing the average of the two
tensions. If the spokes are at very different tensions, the tone is
dull. Here is what I said in my article, :
"On a radially-spoked wheel or one whose spokes are not laced, you can
pluck one spoke at a time. If spokes are laced, pluck them where they
cross. You will be listening to the sound of two spokes at once.
"If the tension of two laced spokes is very different, you will hear a
dull thud. Pull the spokes across each other with your fingers to see
which one is looser. Lift the looser spoke away to pluck the tighter one
alone and check its pitch."
It is also possible to hear pitches for the two spokes individually by
damping the spokes at the cross with one hand, and plucking the segment
between the cross and the rim with the other hand.
The point is that the example ignores that the two spokes with twice
the mass have twice the tension. In fact it is a sleight of hand with
now you see it, now you don't. The example demonstrates that the wire
thickness (aka mass) is a parameter in the resonance unlike what Allen
says.
Right, they have twice the mass and twice the tension. Neglecting
bending stiffness, which has a minor effect, the resonant frequency
increases as the square root of the tension and decreases as the square
root of the mass. Result: the resonant frequency stays the same, to a
close approximation. Now, let Brandt please explain why he disagrees
with this .
He stated that pedaling standing substantially increases spoke
tension, something that comes up regularly here from the naysayers.
This is not true. The differences in tension are loss of tension of
the downward directed spokes not an increase in the upper spokes.
This all arises from the "hang from the top" spoke visualization. I
didn't go into detail to spare the readers the following invective
that comes from such concept.
Here is the passage Brandt is criticizing, in
http://www.bikexprt.com/bicycle/pitcheqn.htm:
"Weight loading on a wheel decreases tension of the few spokes at the
bottom of the wheel greatly, and raises tension of the remaining spokes
only very slightly, but lateral loading while pedaling out of the saddle
causes significant increases in spoke tension and can lead to rapid
failure of an overtensioned wheel."
It should be entirely clear from this that I don't subscribe to the
"hanging from the top" fallacy and that I described the added tension
while standing as due to lateral loading of the wheel. I didn't bother
to indicate that this loading results from the leaning the bicycle from
side to side under the rider, because I thought this was quite obvious.
Brandt has misread me, but on the other hand, I might have explained
myself more clearly. I think him for raising this issue, and I have
revised the article accordingly.
John S. Allen
7 University Park
Waltham, MA 02453-1523 USA
781 891-9307
jsa...@bikexprt.com
http://www.bikexprt.com
jobst....@stanfordalumni.org
>> you can make a simple judgment on this scenario for yourself - do
>> the ping test. exert a lateral load on a wheel so the rim touches
>> one brake pad for example. pluck a spoke on that same side.
>> notice the change of pitch compared to when you're /not/ exerting
>> that lateral load?
>> increase in pitch = increase in tension. that's fact. substantial
>> lateral load substantially increases tension. that's fact too.
> Both facts, however, they need to be connected. Back in April I
> posted my simple test of the effect of lateral loading on spoke
> tension, estimated via the change in tone. A change in a semitone
> (my estimate of the maximum change due to pushing the rim sideways
> so that it touches the pad) represents a change in tension of
> 4^(1/12) ~ 12%; not insignificant but also not what I would consider
> "substantial".
> On the road, however, the rear wheel is not displaced by laterally
> loading the rim at the brake, which minimizes the required force.
> The forces involved may require substantial changes in spoke
> tension. That has to be shown.
I agree and that is easily done. I suggest that you stand on the
pedals and lean the bicycle to the side, as one does when pedaling on
a hill, and do a tone test. You'll find that there is no significant
change in tension of the upper spokes (the ones near the brake pad).
This is a false visualization of spoke stresses similar to "the wheel
hangs from the top spokes" scenario. The change lies in the amount of
slackening of left and right spokes at the ground contact zone.
Suggesting that one push the rim laterally by hand and measure tension
changes is an unrealistic image of what occurs when bicycle wheels
support off axis loads.
jobst....@stanfordalumni.org
> Date: Tue, 14 Jun 2005
> To: Sheldon Brown <Capt...@sheldonbrown.com>
> From: "John S. Allen" <jsa...@bikexprt.com>
> Subject: Re: Spoke tension meter (rec.bicycles.tech
> Cc: Jobst....@stanfordalumni.org
> Following is my reply to Jobst Brandt's criticisms of my articles on
> spoke tension, which Sheldon Brown forwarded to me. I am distressed by
> Brandt's broad and nonspecific criticisms when, in fact, I agree with
> almost everything he has to say about wheelbuilding, and I have long
> used and cited his book, The Bicycle Wheel.
> ***************
> Anyway, Brandt said: ...
My criticism is pointed and narrow and concern that spoke thickness
affects tone and pedaling standing does not significantly affect spoke
stress. Reading this response I see no explanation of what appears
in:
http://bikexprt.com/bicycle/pitcheqn.htm
Specifically, he ignores having said that spoke thickness has no
effect on pitch of a plucked spoke.
Additionally he doesn't explain the other false claim that pedaling
while standing significantly increases spokes stress.
I sense Washington DC spin doctors are at work here.
Marvin
> Joe Riel writes:
>
> > On the road, however, the rear wheel is not displaced by laterally
> > loading the rim at the brake, which minimizes the required force.
> > The forces involved may require substantial changes in spoke
> > tension. That has to be shown.
>
> I agree and that is easily done. I suggest that you stand on the
> pedals and lean the bicycle to the side, as one does when pedaling on
> a hill, and do a tone test. You'll find that there is no significant
> change in tension of the upper spokes (the ones near the brake pad).
>
> This is a false visualization of spoke stresses similar to "the wheel
> hangs from the top spokes" scenario. The change lies in the amount of
> slackening of left and right spokes at the ground contact zone.
I'm not convinced here. I'll accept (as in the Bicycle Wheel) that
spokes lose tension from a radial load, so the spokes at the bottom of
a wheel are the lightest loaded. I'll also accept that lateral loading
has no overall effect, only to change the balance between left and
right side spokes. This obviously means one side increases in tension
relative to the other.
As I understand it, Jobst's assertion is that the increase in tension
on the higher-tension side is not enough to outweight the decrease in
tension from the radial loading. It's easy to construct a
counterexample to this - imagine a circus bike with wheels designed to
run almost parallel to the ground. The question is, at what point does
the loosening from radial force exactly equal the tightening of one
side from lateral force?
> Suggesting that one push the rim laterally by hand and measure tension
> changes is an unrealistic image of what occurs when bicycle wheels
> support off axis loads.
It's not an unrealistic image of a load whose only component is axial,
it's not necessarily representative of real-world riding. Exactly what
*is* representative of real-world riding is something I think Carl
Fogel asked some way up the thread, and I'd be quite interested to find
out.
carl...@comcast.net
Dear Jobst,
Does it matter that anyone who manages this is only
balancing motionless, not stomping down onto the pedal?
That is, are the forces on some precariously balanced static
model comparable to what happens when we're actually
pedalling up a hill?
Come to think of it, standing on the pedals, leaning to the
side, and plucking a spoke all at once sounds a bit tricky,
at least if you're really standing on the pedal and leaning
without support.
It does seem to be a tricky situation to test.
If I'm following you, the theory is that the tension on the
upper spokes remains essentially unchanged, and that the
action involves the lower spokes slackening even more than
usual as they roll under the hub.
Have I misunderstood the idea that the upper rim moves
enough to rub the brake pads when leaned over and climbing?
Or does it somehow move without changing tension in response
to the spokes on the bottom losing tension?
Carl Fogel
carl...@comcast.net
Dear Jobst,
I sense that your paranoia is overflowing again.
Incidentally, your original complaint was broad and vague,
not pointed and narrow:
"There are other misleading items in Allen's website about
spoke tension as well. I would avoid citing that source."
You certainly did avoid citing it in that post, while
calling it misleading, which was what Sheldon pointed out.
Carl Fogel
Bill Sornson
> Sheldon Brown <capt...@sheldonbrown.com> writes:
>> Date: Tue, 14 Jun 2005
>> To: Sheldon Brown <Capt...@sheldonbrown.com>
>> From: "John S. Allen" <jsa...@bikexprt.com>
>> Subject: Re: Spoke tension meter (rec.bicycles.tech
>> Cc: Jobst....@stanfordalumni.org
>
>> Following is my reply to Jobst Brandt's criticisms of my articles on
>> spoke tension, which Sheldon Brown forwarded to me. I am distressed
>> by Brandt's broad and nonspecific criticisms when, in fact, I agree
>> with almost everything he has to say about wheelbuilding, and I have
>> long used and cited his book, The Bicycle Wheel.
>
>> ***************
>> Anyway, Brandt said: ...
>
> My criticism is pointed and narrow and concern that spoke thickness
> affects tone and pedaling standing does not significantly affect spoke
> stress.
Pointed and narrow? "There are other misleading items in Allen's website
about spoke tension
as well. I would avoid citing that source."
Sounds pretty broad and nonspecific to at least one observer. (Two counting
Allen himself.)
jobst....@stanfordalumni.org
>>> On the road, however, the rear wheel is not displaced by laterally
>>> loading the rim at the brake, which minimizes the required force.
>>> The forces involved may require substantial changes in spoke
>>> tension. That has to be shown.
>> I agree and that is easily done. I suggest that you stand on the
>> pedals and lean the bicycle to the side, as one does when pedaling
>> on a hill, and do a tone test. You'll find that there is no
>> significant change in tension of the upper spokes (the ones near
>> the brake pad).
>> This is a false visualization of spoke stresses similar to "the
>> wheel hangs from the top spokes" scenario. The change lies in the
>> amount of slackening of left and right spokes at the ground contact
>> zone.
> I'm not convinced here. I'll accept (as in the Bicycle Wheel) that
> spokes lose tension from a radial load, so the spokes at the bottom
> of a wheel are the lightest loaded. I'll also accept that lateral
> loading has no overall effect, only to change the balance between
> left and right side spokes. This obviously means one side increases
> in tension relative to the other.
Oops! No, that is not the case. One side loses more tension than the
other and only at the ground contact zone. You needn't take this on
faith. It is easy to test as has been explained.
> As I understand it, Jobst's assertion is that the increase in
> tension on the higher-tension side is not enough to outweight the
> decrease in tension from the radial loading. It's easy to construct
> a counterexample to this - imagine a circus bike with wheels
> designed to run almost parallel to the ground. The question is, at
> what point does the loosening from radial force exactly equal the
> tightening of one side from lateral force?
I did not say that. I said there is no significant increase in
tension when the wheel is loaded off axis, typically, when pedaling
standing.
>> Suggesting that one push the rim laterally by hand and measure
>> tension changes is an unrealistic image of what occurs when bicycle
>> wheels support off axis loads.
> It's not an unrealistic image of a load whose only component is
> axial, it's not necessarily representative of real-world riding.
> Exactly what *is* representative of real-world riding is something I
> think Carl Fogel asked some way up the thread, and I'd be quite
> interested to find out.
The "real world" is representative of real-world riding. Try it.
jobst....@stanfordalumni.org
> Does it matter that anyone who manages this is only balancing
> motionless, not stomping down onto the pedal?
No, because torque transmission of a rear wheel is insignificantly
small compared to the tension relaxation of the few spokes in the
ground contact zone. That the rider i lunging downward also makes no
difference to the balance of tension, it only makes him appear a bit
heavier at that moment but the load distribution is given by rider CG
with respect to the normal through the tire contact line.
> That is, are the forces on some precariously balanced static model
> comparable to what happens when we're actually pedalling up a hill?
Yes, although the magnitudes may vary. Riders do not have much
vertical acceleration so the change is small.
> Come to think of it, standing on the pedals, leaning to the side,
> and plucking a spoke all at once sounds a bit tricky, at least if
> you're really standing on the pedal and leaning without support.
I'm sure a friend would assist in this task.
> It does seem to be a tricky situation to test.
Imagination... use imagination on accomplishing it.
> If I'm following you, the theory is that the tension on the upper
> spokes remains essentially unchanged, and that the action involves
> the lower spokes slackening even more than usual as they roll under
> the hub.
> Have I misunderstood the idea that the upper rim moves enough to rub
> the brake pads when leaned over and climbing? Or does it somehow
> move without changing tension in response to the spokes on the
> bottom losing tension?
Try it. Don't just ask. Take your own word for it.
jobst....@stanfordalumni.org
# The cross-sectional area of the spoke and the mass per unit length m
# are exactly proportional to each other. Therefore, for two different
# strings or wires of equal length, one thick and another thin, the
# frequency is the same if the tension per unit of cross-sectional
# area is the same. One way to think of this is to imagine two
# identical spokes side by side, both of the same gauge and at the
# same tension. They vibrate at the same frequency. Now imagine
# lightly connecting them together all along their length. They still
# vibrate at the same frequency. Finally, imagine merging them into
# one, thicker spoke. It still vibrates at the same frequency.
# ...
# 1. The derivation of this formula is given, for example, in Alonso
# and Finn, Fundamental University Physics vol. 2, Fields and Waves
# (1967, Addison Wesley), section 18-7.
#
# 2. It follows from the analysis here that the changes in tension of
# spokes in a bicycle wheel under load may simply and elegantly be
# demonstrated by measuring the changes in their musical pitch. This
# is easiest in a radially-spoked or unlaced wheel.
Although not saying that spoke thickness has no effect on tone, it is
implied clearly enough and is given in response to questions on the
use of a tensiometer to assess proper tension.
What Allen proposes is that spoke stress be the parameter of interest
and that with the same stress, uniform thickness spokes will have the
same tone when plucked. Although this is true, it is not what was
suggested in the reference to tone tensioning, which suggested tension
could be derived from tone. This article gives the impression that
the tone is relative to tension only, something the example disproves,
there being twice the tension in the Siamesed spokes mentioned.
Besides, spoke stress is not what the wheelbuilder wants to know,
since correct spoke tension is prescribed for a specific rim, rather
than stress in its spokes. A tensiometer is commonly used to measure
that tension while tone is commonly used to balance tension among
spokes, regardless of whether straight gauge or swaged, thick or thin.
If that were not the case, then DT Revolution spokes would not be
used, having only 56% the tensile strength of 2.0mm spokes, also used
for a similar wheel.
bikeguy11968
flipper type guy could afford whatever spoke tensiometer he wanted to
if he didn't waste his time reading this crap, looking at websites
attempting to relate plucked tension of spokes, and worked a couple of
extra shifts..
m
jim beam
> What is misleading in the item:
>
> # The cross-sectional area of the spoke and the mass per unit length m
> # are exactly proportional to each other. Therefore, for two different
> # strings or wires of equal length, one thick and another thin, the
> # frequency is the same if the tension per unit of cross-sectional
> # area is the same. One way to think of this is to imagine two
> # identical spokes side by side, both of the same gauge and at the
> # same tension. They vibrate at the same frequency. Now imagine
> # lightly connecting them together all along their length. They still
> # vibrate at the same frequency. Finally, imagine merging them into
> # one, thicker spoke. It still vibrates at the same frequency.
>
> # ...
>
> # 1. The derivation of this formula is given, for example, in Alonso
> # and Finn, Fundamental University Physics vol. 2, Fields and Waves
> # (1967, Addison Wesley), section 18-7.
> #
> # 2. It follows from the analysis here that the changes in tension of
> # spokes in a bicycle wheel under load may simply and elegantly be
> # demonstrated by measuring the changes in their musical pitch. This
> # is easiest in a radially-spoked or unlaced wheel.
>
> Although not saying that spoke thickness has no effect on tone, it is
> implied clearly enough and is given in response to questions on the
> use of a tensiometer to assess proper tension.
jobst, why does your own tensiometer math ignore spoke thickess? - it's
an integral part of the equation. maybe you think it's "insignificant",
just like increasing spoke tension with lateral deflection? and why do
i have to ask you twice?
>
> What Allen proposes is that spoke stress be the parameter of interest
> and that with the same stress, uniform thickness spokes will have the
> same tone when plucked. Although this is true, it is not what was
> suggested in the reference to tone tensioning, which suggested tension
> could be derived from tone. This article gives the impression that
> the tone is relative to tension only, something the example disproves,
> there being twice the tension in the Siamesed spokes mentioned.
that's nto waht he says at all. you're tryint to put words in his mouth.
>
> Besides, spoke stress is not what the wheelbuilder wants to know,
> since correct spoke tension is prescribed for a specific rim, rather
> than stress in its spokes. A tensiometer is commonly used to measure
> that tension while tone is commonly used to balance tension among
> spokes, regardless of whether straight gauge or swaged
butted jobst, butted. "swaged" is a specific process unique to one
manufacturer, not the generic term that can be applied to all such spokes.
>, thick or thin.
> If that were not the case, then DT Revolution spokes would not be
> used, having only 56% the tensile strength of 2.0mm spokes, also used
> for a similar wheel.
ridiculous twisted obfuscation.
>
> Jobst....@stanfordalumni.org
>
>
>
>
>
>
jim beam
> Joe Riel writes:
>
>
>>>you can make a simple judgment on this scenario for yourself - do
>>>the ping test. exert a lateral load on a wheel so the rim touches
>>>one brake pad for example. pluck a spoke on that same side.
>>>notice the change of pitch compared to when you're /not/ exerting
>>>that lateral load?
>
>
>>>increase in pitch = increase in tension. that's fact. substantial
>>>lateral load substantially increases tension. that's fact too.
>
>
>>Both facts, however, they need to be connected. Back in April I
>>posted my simple test of the effect of lateral loading on spoke
>>tension, estimated via the change in tone. A change in a semitone
>>(my estimate of the maximum change due to pushing the rim sideways
>>so that it touches the pad) represents a change in tension of
>>4^(1/12) ~ 12%; not insignificant but also not what I would consider
>>"substantial".
>
>
>>On the road, however, the rear wheel is not displaced by laterally
>>loading the rim at the brake, which minimizes the required force.
>>The forces involved may require substantial changes in spoke
>>tension. That has to be shown.
>
>
> I agree and that is easily done. I suggest that you stand on the
> pedals and lean the bicycle to the side, as one does when pedaling on
> a hill, and do a tone test. You'll find that there is no significant
> change in tension of the upper spokes (the ones near the brake pad).
wow! that's a particularly brazen shameless twisting of the facts!!!
what about the tension changes at the /bottom/ of the wheel, you know,
the bit where the rim's bending??? jobst, you take the prize!!!
> This is a false visualization of spoke stresses similar to "the wheel
> hangs from the top spokes" scenario.
deliberate obfuscation.
> The change lies in the amount of
> slackening of left and right spokes at the ground contact zone.
the tension /increases/ on the side which is experiencing the lean
jobst. try it.
>
> Suggesting that one push the rim laterally by hand and measure tension
> changes is an unrealistic image of what occurs when bicycle wheels
> support off axis loads.
why? because it exposes the nakedness of your convoluted arguments?
jim beam
follow. amazing clarity among all this mud.
jim beam
> jim beam <nos...@example.net> writes:
>
>
>>does it ever creep you out to have someone pose as an "expert" when
>>they're really not? do you fancy visiting a doctor like that? what
>>about a surgeon? how about flying in a plane designed by someone that
>>doesn't understand metal fatigue?
>
>
> OK. I guess I was underestimating
sorry, that would be "overestimating".
then again, you may have a point; if brandt hadn't used the immortal
words "tension as high as the rim can bear" in his book, words bourne of
the basic misconception that increasing tension somehow magically
increases wheel strength, we'd never have a pre-built wheel industry
today. pre-built is the only reasonable way in which manufacturers
could seek to avoid endless [expensive] returns from rims that had
cracked due to jobstian over-tension, [which was in turn mis-attributed
to anodizing, but that's another basic misconception].
> Jobst Brandt's influence in the
> bike world. Your use of the word "expert" also piqued a vague sense
> that I had heard that he testifies as an expert witness in bike cases.
have you ever been involved with being an expert witness? it's a
process where the opportunity to technically bamboozle the uninitiated
presents itself and accuracy takes a back seat to the slant of the
argument the litigants are trying to present. in this respect, jobst is
perfect. his shameless bullying is his hireable asset, not whether he
knows a damned thing about what he's saying. i'd love to know the
number of cases in which the attorney hiring him won. and against whom.
daveornee
wheel.
--
daveornee
jim beam
know is here:
http://sheldonbrown.com/wheelbuild.html
apart from the fact that sheldon has allowed himself to be bullied into
using "swaged" as a generic term, [although he appears to have some
personal reservations about using that word since he follows it with
"butted" in parentheses], it tells you what to do perfectly.
this is the beauty of the internet and usenet. share what you know,
learn what you don't - or whatever dejanews used to have as their
catch-phrase. besides which, i have no desire to sell you anything.
Sheldon Brown
John could be clearer in his use of the word "tension." He uses this
not in the sense of absolute tension (pounds or dynes) but tension per
cross-sectional area (PSI or dynes/cm2.)
> Besides, spoke stress is not what the wheelbuilder wants to know,
> since correct spoke tension is prescribed for a specific rim, rather
> than stress in its spokes.
That's true with modern lightweight rims and high quality spokes. It is
not universally true, however, and at the time John was doing the
research that led to this article lower quality spokes were the norm, as
were heavier, stronger rims.
Back in the '70s and early '80s, nipples pulling through the rim were
exceedingly uncommon, and the usual cause of spoke breakage was
insufficient spoke tension. Tensiometers were not generally available,
and John provided a useful service by offering a way an inexperienced
wheelbuilder could get some idea of correct spoke tension.
I used to use this system myself, before I got a tensiometer (I made a
cassette tape with a couple of piano notes on it, since the shop I
worked at at the time didn't posses a piano.)
I don't believe the use of a tensiometer resulted in any improvement in
the quality of my wheels.
> A tensiometer is commonly used to measure
> that tension while tone is commonly used to balance tension among
> spokes, regardless of whether straight gauge or swaged, thick or thin.
Yep. Actually, Park Tools offers a system where you can measure the
tension on _each_ spoke with their tensiometer, then enter the data into
an Excel spreadsheet template they supply, then get a graphical
representation of the wheel's tension in polar coordinates.
I've never heard of anybody actually using this though. You gotta draw
the line somewhere!
Sheldon "Empiricist" Brown
+--------------------------------------------+
| Never worry about theory as long as the |
| machinery does what it's supposed to do. |
| --Robert A. Heinlein |
+--------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com
SocSecTr...@earthlink.net
Sheldon Brown wrote:
> > Besides, spoke stress is not what the wheelbuilder wants to know,
> > since correct spoke tension is prescribed for a specific rim, rather
> > than stress in its spokes.
>
> That's true with modern lightweight rims and high quality spokes. It is
> not universally true, however, and at the time John was doing the
> research that led to this article lower quality spokes were the norm, as
> were heavier, stronger rims.
>
> Back in the '70s and early '80s, nipples pulling through the rim were
> exceedingly uncommon, and the usual cause of spoke breakage was
> insufficient spoke tension. Tensiometers were not generally available,
> and John provided a useful service by offering a way an inexperienced
> wheelbuilder could get some idea of correct spoke tension.
Are you sure about your statement that heavier, stronger rims were the
norm in the past (70s-early 80s)? It seems to me that the norm in the
70s was a 270-350g rim, and that they are now heavier, at least in part
due to the more extreme dishing requirements of 8s+ rear wheels, and
maybe also to handle higher spoke tension required by a lower spoke
count. (All bicycle compeonents seemed to get heavier in the mid 80s,
including rims. The trend reversed later, but rims seemed to remain
heavier, possibly because the above trends started to impact rim
design.) Maybe my impression is the result of involvement in racing,
tubular rims, and bike shops that catered to racing cyclists. Maybe the
trend was different for clincher rims- they do seem to have gotten
lighter over the same period as they have come to be considered an
alternative to tubulars for "serious" cyclists.
JeffWills
TrainWreck wrote:
>
> Are you sure about your statement that heavier, stronger rims were the
> norm in the past (70s-early 80s)? It seems to me that the norm in the
> 70s was a 270-350g rim,
<snip>
> Maybe my impression is the result of involvement in racing,
> tubular rims, and bike shops that catered to racing cyclists. Maybe the
> trend was different for clincher rims- they do seem to have gotten
> lighter over the same period as they have come to be considered an
> alternative to tubulars for "serious" cyclists.
I think you've analyzed it correctly- tubular rims from days of yore
were 250 to 350 grams, where most clincher rims were in the
500-gram-ish range. Nowadays, clincher rims in the 400 gram range are
relatively common, while you'll have a hard time finding *any* tubular
rims in a shop now.
Nashbar has some:
http://www.nashbar.com/profile.cfm?brand=1317&sku=12561
Yikes! 480 grams!
http://www.nashbar.com/profile.cfm?brand=1317&sku=12555
Jeff
Marvin
> Marvin Meredith writes:
>
> >>> On the road, however, the rear wheel is not displaced by laterally
> >>> loading the rim at the brake, which minimizes the required force.
> >>> The forces involved may require substantial changes in spoke
> >>> tension. That has to be shown.
>
> >> I agree and that is easily done. I suggest that you stand on the
> >> pedals and lean the bicycle to the side, as one does when pedaling
> >> on a hill, and do a tone test. You'll find that there is no
> >> significant change in tension of the upper spokes (the ones near
> >> the brake pad).
But as any good student of the Bicycle Wheel will know, tension changes
from ground contact only affect the bottom few spokes in any
significant manner. Surely it's those we ought to be measuring?
> >> This is a false visualization of spoke stresses similar to "the
> >> wheel hangs from the top spokes" scenario. The change lies in the
> >> amount of slackening of left and right spokes at the ground contact
> >> zone.
>
> > I'm not convinced here. I'll accept (as in the Bicycle Wheel) that
> > spokes lose tension from a radial load, so the spokes at the bottom
> > of a wheel are the lightest loaded. I'll also accept that lateral
> > loading has no overall effect, only to change the balance between
> > left and right side spokes. This obviously means one side increases
> > in tension relative to the other.
>
> Oops! No, that is not the case. One side loses more tension than the
> other and only at the ground contact zone. You needn't take this on
> faith. It is easy to test as has been explained.
Yes, I just tested it and got exactly the result I expected - higher
tension in the spokes nearest the ground. Perhaps we're measuring
different things, so I'll describe this in painstaking detail.
I sit on a bike, holding a wall for support but otherwise as upright as
I can get. My lovely assistant pings all the spokes in the front
wheel, and they conform to what the Bicycle Wheel suggests - drop of
tension in about four spokes around the ground contact, all others
even.
I lean the bike to the left whilst leaning myself right to load the
wheel axially, and she repeats the experiment. All the spokes have
even tension except the load-affected ones. Of those, the righthand
spokes have lower tension than anything so far, and the lefthand spokes
have higher tension than they ever did. For those of you who
skipped to the interesting bit: leaning the bike raised the spoke
tension.
My assistant leaves with a shrug of her shoulders and "see, I could
have told you that".
If I'm measuring the wrong thing, please do tell me what I'm doing
wrong, but otherwise I think a rethink is in order.
Joe Riel
> the tension /increases/ on the side which is experiencing the lean
Not necessarily. Consider the wheel as a simple three-element truss.
With the bike in the upright position, a pure radial load is applied
to the structure. As it is leaned, a lateral component is introduced.
However, unless the bike is leaned so that the bottom spokes go past
the vertical the net effect is a reduction in tension (draw the
triangle to verify this). While it is certainly possible to go past
the vertical, I don't believe that this is done during the typical
standing/climbing technique. At most one can go only somewhat past
vertical, otherwise the top tube will be slapping into your knee
or you will be using an exaggerated motion.
The simple model of the wheel used above is not, alas, complete.
As pointed out in "Bicycling Science" (3rd ed.) more spokes are
affected by a lateral load than by a radial load. Maybe the spokes
around the bottom spoke(s) see an increase in tension.
Joe
Joe Riel
> I lean the bike to the left whilst leaning myself right to load the
> wheel axially, and she repeats the experiment. All the spokes have
> even tension except the load-affected ones. Of those, the righthand
> spokes have lower tension than anything so far, and the lefthand spokes
> have higher tension than they ever did. For those of you who
> skipped to the interesting bit: leaning the bike raised the spoke
> tension.
>
> My assistant leaves with a shrug of her shoulders and "see, I could
> have told you that".
>
> If I'm measuring the wrong thing, please do tell me what I'm doing
> wrong, but otherwise I think a rethink is in order.
I'm assuming that this was for a rear wheel.
Try again but this time lean the bike to the right. We aren't much
interested in tension increases in the left-hand spokes, they have
significantly less tension than the right-hand spokes. You'll find
that you have to lean the bike significantly further to increase the
tension above the nominal (unloaded). That is, the tension in
the right-hand spokes shouldn't increase (based on simple model)
above the nominal until the left-hand spokes go past vertical, which
takes a larger lean because of the dish of the rear wheel.
My observation is that the required lean to increase the tension is
outside what one would normally experience in riding (including,
of course, standing).
Joe
Jim Smith
> Yep. Actually, Park Tools offers a system where you can measure the
> tension on _each_ spoke with their tensiometer, then enter the data
> into an Excel spreadsheet template they supply, then get a graphical
> representation of the wheel's tension in polar coordinates.
>
> I've never heard of anybody actually using this though. You gotta
> draw the line somewhere!
Heh. I actually did this using Matlab on the last wheels I built.
Making the graph is trivial, but measuring all the spokes and entering
the data took a couple minutes. It was sort of fun (for small values
of "fun") to watch the graph become a nice round circle over a couple
of iterations.
Sheldon Brown
>>Back in the '70s and early '80s, nipples pulling through the rim were
>>exceedingly uncommon, and the usual cause of spoke breakage was
>>insufficient spoke tension. Tensiometers were not generally available,
>>and John provided a useful service by offering a way an inexperienced
>>wheelbuilder could get some idea of correct spoke tension.
>
Someone who didn't want to reveal his/her secret identity replied:
>
> Are you sure about your statement that heavier, stronger rims were the
> norm in the past (70s-early 80s)?
Yes.
> It seems to me that the norm in the 70s was a 270-350g rim,
No, only racers (and racer-wannabes) used rims that light.
> and that they are now heavier, at least in part
> due to the more extreme dishing requirements of 8s+ rear wheels,
Good point about the extra dish and the generally higher stresses it
introduced.
In addition, there's the great spoke scam, where manufacturers skimp on
spoke numbers, saving major money in the process, and have actually
managed to convince gullible consumers that fewer spokes is a "feature"!
and
> maybe also to handle higher spoke tension required by a lower spoke
> count. (All bicycle compeonents seemed to get heavier in the mid 80s,
> including rims.
Yes, the great aero fad of the early '80s.
> The trend reversed later, but rims seemed to remain
> heavier, possibly because the above trends started to impact rim
> design.) Maybe my impression is the result of involvement in racing,
> tubular rims, and bike shops that catered to racing cyclists. Maybe the
> trend was different for clincher rims- they do seem to have gotten
> lighter over the same period as they have come to be considered an
> alternative to tubulars for "serious" cyclists.
"Serious" cyclists have always preferred clinchers.
Amateur racing is hardly "serious" cycling, and there is no sigificant
pro racing in the U.S.. ;-)
Sheldon "Serious Commuter" Brown
+----------------------------------------------+
| Certainly the game is rigged. |
| Don't let that stop you; |
| if you don't bet, you can't win. |
| --Robert A. Heinlein |
+----------------------------------------------+
carl...@comcast.net
<capt...@sheldonbrown.com> wrote:
[snip--twang!]
>I used to use this system myself, before I got a tensiometer (I made a
>cassette tape with a couple of piano notes on it, since the shop I
>worked at at the time didn't possess a piano.)
[snip--ping!]
Dear Sheldon,
Surely Harris Cyclery is equipped with a Park Tools
Spoke-Tuning Piano or a Hozan Harpsichord to check the
tensiometer, but I can't find the part number for either
instrument.
Carl Fogel
SocSecTr...@earthlink.net
> "Serious" cyclists have always preferred clinchers.
Recalling the dim past, no, most of the cyclists that I knew then (even
before the time I spent in Germany, where I did a lot of cycling with
pros) that could afford the good bikes were riding tubulars, that's
what they were equipped with. Remember the PX10? It was a common
high-end production bike and its rims were light by today's standards.
Some people may have bought them as status symbols but everyone I knew
who had these types of bikes just loved cycling. The people who did a
lot of riding on top quality bikes rode tubulars.
> Amateur racing is hardly "serious" cycling, and there is no sigificant
> pro racing in the U.S.. ;-)
We'll have to agree to disagree on the definition of serious.
Personally, I think John Howard was pretty serious. I think the German
amateurs I knew who aspired to be pros were pretty serious, too. For
the life of me, I can't tell why someone who rides 300mi./wk. trying to
become a better racer can't be considered serious because they never
reach the pro ranks. That really is an elitist view of our sport that
is pretty insulting to tens of thousands of cyclists.
Here's my definition of "serious": anyone who says (with sincerity,
obviously) they are.
Luns Tee
Sheldon Brown <capt...@sheldonbrown.com> wrote:
>John could be clearer in his use of the word "tension." He uses this
>not in the sense of absolute tension (pounds or dynes) but tension per
>cross-sectional area (PSI or dynes/cm2.)
Why not use the proper word for this instead of fuzzying up the
meaning of another? Force per unit area is stress.
-Luns
Luns Tee
>exceedingly uncommon, and the usual cause of spoke breakage was
>insufficient spoke tension.
While we're at it.. please explain how insufficient spoke
tension causes spoke breakage. Inadequate tension produces an inferior
wheel, certainly, but the failure of low spoke tension is that spokes
go slack under load, allowing spoke nipples to rattle loose and the
wheel to then go out of true. Spoke breakage is not part of this, even
if it was more common at the time. But so were bell bottom pants.
Bell bottom pants cause spoke breakage!
-Luns
Luns Tee
>not in the sense of absolute tension (pounds or dynes) but tension per
>cross-sectional area (PSI or dynes/cm2.)
Why not use the proper word for this instead of fuzzying up the
meaning of another? Force per unit area is stress.
>Back in the '70s and early '80s, nipples pulling through the rim were
>exceedingly uncommon, and the usual cause of spoke breakage was
>insufficient spoke tension.
Please explain how insufficient spoke tension causes spoke
breakage. Inadequate tension produces an inferior wheel, certainly,
but the failure of low spoke tension is that spokes go slack under
load, allowing spoke nipples to rattle loose and/or the rim to yield,
Jay Beattie
<SocSecTr...@earthlink.net> wrote in message
news:1118872814.7...@g44g2000cwa.googlegroups.com...
> Sheldon Brown wrote:
> > "Serious" cyclists have always preferred clinchers.
>
> Recalling the dim past, no, most of the cyclists that I knew
then (even
> before the time I spent in Germany, where I did a lot of
cycling with
> pros) that could afford the good bikes were riding tubulars,
that's
> what they were equipped with. Remember the PX10? It was a
common
> high-end production bike and its rims were light by today's
standards.
My PX10 came with Monthlery Pros, which were a 400 gram tubular
rim -- the same weight as my current Aeorohead OC clincher rim.
Other models of the Monthlery were lighter, though. The relative
light rims on the PX10 made little difference in the grand scheme
of things because of the (felt like) three pound Simplex seat
post, Pivo stem and boat-anchor Ideal leather saddle.
> Some people may have bought them as status symbols but everyone
I knew
> who had these types of bikes just loved cycling. The people who
did a
> lot of riding on top quality bikes rode tubulars.
I bought my PX10 in highschool because I was enamoured of
bicycles, and I could afford it (used). I couldn't ride worth
sh** -- that came later. I hated gluing tubulars, but anyone who
was "serious" used tubulars back then because the clinchers
really sucked. It was not until the Elan or the Turbo that there
was a competitive clincher -- and not really until the Michelin
SuperCompHD or maybe the Avocet that there was anything that
rivaled mid-fi tubulars.
> > Amateur racing is hardly "serious" cycling, and there is no
sigificant
> > pro racing in the U.S.. ;-)
>
> We'll have to agree to disagree on the definition of serious.
> Personally, I think John Howard was pretty serious. I think the
German
> amateurs I knew who aspired to be pros were pretty serious,
too. For
> the life of me, I can't tell why someone who rides 300mi./wk.
trying to
> become a better racer can't be considered serious because they
never
> reach the pro ranks. That really is an elitist view of our
sport that
> is pretty insulting to tens of thousands of cyclists.
I'm outraged! -- Jay Beattie.
jim beam
the offset for the drive side of a campy hub is only 18mm. even if my
top tube is 3x as high as my hub [which it's not], that's still only
54mm offset from the vertical. check how that is on your bike - it's
not a lot of lean.
jim beam
> I wrote:
>
>>> Back in the '70s and early '80s, nipples pulling through the rim were
>>> exceedingly uncommon, and the usual cause of spoke breakage was
>>> insufficient spoke tension. Tensiometers were not generally available,
>>> and John provided a useful service by offering a way an inexperienced
>>> wheelbuilder could get some idea of correct spoke tension.
>>
>>
> Someone who didn't want to reveal his/her secret identity replied:
>
>>
>> Are you sure about your statement that heavier, stronger rims were the
>> norm in the past (70s-early 80s)?
>
>
> Yes.
>
>> It seems to me that the norm in the 70s was a 270-350g rim,
>
>
> No, only racers (and racer-wannabes) used rims that light.
>
>> and that they are now heavier, at least in part
>> due to the more extreme dishing requirements of 8s+ rear wheels,
>
>
> Good point about the extra dish and the generally higher stresses it
> introduced.
seconded.
and the greater the dish, the greater the stress increase on lateral load.
jim beam
> jim beam <nos...@example.net> writes:
>
>
>>the tension /increases/ on the side which is experiencing the lean
>
>
> Not necessarily. Consider the wheel as a simple three-element truss.
> With the bike in the upright position, a pure radial load is applied
> to the structure. As it is leaned, a lateral component is introduced.
> However, unless the bike is leaned so that the bottom spokes go past
> the vertical the net effect is a reduction in tension (draw the
> triangle to verify this). While it is certainly possible to go past
> the vertical, I don't believe that this is done during the typical
> standing/climbing technique.
as stated in my other response, you only need to get 54mm past vertical
on a /huge/ frame, and obviously less on a smaller one.
> At most one can go only somewhat past
> vertical, otherwise the top tube will be slapping into your knee
> or you will be using an exaggerated motion.
even sitting, you can accomodate a fair degree of top tube displacement.
on long rides, i sometimes "sit on one edge" of the saddle to relieve
pressure. standing, as above, i tend to lay the bike from side to side,
well past vertical, and certainly more than 54mm.
>
> The simple model of the wheel used above is not, alas, complete.
> As pointed out in "Bicycling Science" (3rd ed.) more spokes are
> affected by a lateral load than by a radial load. Maybe the spokes
> around the bottom spoke(s) see an increase in tension.
sure, but there's not much "maybe" about it - the ping test reveals all!
>
> Joe
jim beam
> In article <42B055D7...@sheldonbrown.com>,
> Sheldon Brown <capt...@sheldonbrown.com> wrote:
>
>>Back in the '70s and early '80s, nipples pulling through the rim were
>>exceedingly uncommon, and the usual cause of spoke breakage was
>>insufficient spoke tension.
>
>
> While we're at it.. please explain how insufficient spoke
> tension causes spoke breakage. Inadequate tension produces an inferior
> wheel, certainly, but the failure of low spoke tension is that spokes
> go slack under load, allowing spoke nipples to rattle loose and the
> wheel to then go out of true.
slack spokes are not intrinsically less strong, and as you point out,
their biggest problem is tendency to loosen, but there /is/ a
reliability problem with them. it's caused by exaggerated bending as a
result of their interaction with their crossing partner. spokes
typically fatigue at the elbow as a result of bending - they are not
axially loaded. if the motion they experience is exaggerated because of
excessive [slack] spoke movement, and even further exaggerated by their
[still taught] crossing partner creating even more lateral movement, the
[bending] strain they experience at the elbow increases and their
fatigue life correspondingly decreases.
Luns Tee
jim beam <nos...@example.net> wrote:
>slack spokes are not intrinsically less strong, and as you point out,
>their biggest problem is tendency to loosen, but there /is/ a
>reliability problem with them. it's caused by exaggerated bending as a
>result of their interaction with their crossing partner. spokes
>typically fatigue at the elbow as a result of bending - they are not
>axially loaded. if the motion they experience is exaggerated because of
>excessive [slack] spoke movement, and even further exaggerated by their
>[still taught] crossing partner creating even more lateral movement, the
>[bending] strain they experience at the elbow increases and their
>fatigue life correspondingly decreases.
If there were any truth to this, then left side spokes on rear
wheels would universally fatigue more than right side spokes do. My
experience with fatigued spokes has been consistently the opposite. My
experience with fatigued spokes also ended with stress releiving the
surviving spokes on the wheels that had failures, something which
should have made no effect according to your movement theory.
-Luns
Joe Riel
> the offset for the drive side of a campy hub is only 18mm. even if my
> top tube is 3x as high as my hub [which it's not], that's still only
> 54mm offset from the vertical. check how that is on your bike - it's
> not a lot of lean.
Agreed. However, the bike doesn't lean much, even while standing
during a climb. Try it. Look at the pictures that were linked
to in this thread.
On reflection, though I wouldn't be surprised if the bottom spoke does
move past the perpendicular. But does it enough to cause a
significant tension increase? I suspect not. I leaned my bike (to
the right) against a wall, at an angle that I might achieve during
out-of-the-saddle climbing. The bottom spoke was past vertical. I
then stood on the left side of the bottom bracket, facing backwards,
reached down and plucked the bottom spoke. I could detect no change
in tone upon removing my weight. This isn't a perfect test, but it
does indicate that an increase in tension is not going to be large.
If I leaned the bike enough I could detect a tension (pitch) increase,
however, the lean was past what I consider realistic.
Joe
Joe Riel
>> The simple model of the wheel used above is not, alas, complete.
>> As pointed out in "Bicycling Science" (3rd ed.) more spokes are
>> affected by a lateral load than by a radial load. Maybe the spokes
>> around the bottom spoke(s) see an increase in tension.
>
> sure, but there's not much "maybe" about it - the ping test reveals all!
See my reply to your other reply. I detected no increase in tension
in the lower right side spokes with the bike leaned at a reasonable
angle (bottom left-side spoke past vertical). Also, pay close attention,
while climing, how much the frame really leans. It isn't as much
as you might think.
To have some numbers to throw around, I (crudely) measured that, with
the bike leaned and tone not changing, the top tube moved six inches
horizontally (my top tube is 31 inches from the ground). The total
side to side movement would then be 12 inches, which is quite a bit.
Joe
carl...@comcast.net
Dear Joe,
What pictures?
Do they show a sequence of side-to-side sway?
I've been wondering about how much actual side-tilt there is
and whether I've been fooled by the shoulder-drop when the
rider sort of twists and curls down (rather than to the
side) toward the foot at the bottom of the stroke.
Elsewhere, Mike Jacoubowsky and RonSonic were trying to
explain something about how differently ordinary and expert
riders move on the bike when standing, so this might be what
they were trying to get at:
(Boy, that new Google is a beast when you want a link to the
right part of the tree!)
Hopefully,
Carl Fogel
jobst....@stanfordalumni.org
>>>>> On the road, however, the rear wheel is not displaced by
>>>>> laterally loading the rim at the brake, which minimizes the
>>>>> required force. The forces involved may require substantial
>>>>> changes in spoke tension. That has to be shown.
>>>> I agree and that is easily done. I suggest that you stand on the
>>>> pedals and lean the bicycle to the side, as one does when
>>>> pedaling on a hill, and do a tone test. You'll find that there
>>>> is no significant change in tension of the upper spokes (the ones
>>>> near the brake pad).
> But as any good student of the Bicycle Wheel will know, tension
> changes from ground contact only affect the bottom few spokes in any
> significant manner. Surely it's those we ought to be measuring?
I think I said that and you quote that below at "Oops".
>>>> This is a false visualization of spoke stresses similar to "the
>>>> wheel hangs from the top spokes" scenario. The change lies in
>>>> the amount of slackening of left and right spokes at the ground
>>>> contact zone.
>>> I'm not convinced here. I'll accept (as in the Bicycle Wheel)
>>> that spokes lose tension from a radial load, so the spokes at the
>>> bottom of a wheel are the lightest loaded. I'll also accept that
>>> lateral loading has no overall effect, only to change the balance
>>> between left and right side spokes. This obviously means one side
>>> increases in tension relative to the other.
>> Oops! No, that is not the case. One side loses more tension than
>> the other and only at the ground contact zone. You needn't take
>> this on faith. It is easy to test as has been explained.
> Yes, I just tested it and got exactly the result I expected - higher
> tension in the spokes nearest the ground. Perhaps we're measuring
> different things, so I'll describe this in painstaking detail.
How far did you lean the bicycle? No doubt as the lean angle get
large, larger than when riding, it starts becoming more a side load on
the wheel similar to pushing the rim sideways at the brake bridge.
> I sit on a bike, holding a wall for support but otherwise as upright
> as I can get. My lovely assistant pings all the spokes in the front
> wheel, and they conform to what the Bicycle Wheel suggests - drop of
> tension in about four spokes around the ground contact, all others
> even.
> I lean the bike to the left whilst leaning myself right to load the
> wheel axially, and she repeats the experiment. All the spokes have
> even tension except the load-affected ones. Of those, the righthand
> spokes have lower tension than anything so far, and the lefthand
> spokes have higher tension than they ever did. For those of you who
> skipped to the interesting bit: leaning the bike raised the spoke
> tension.
> My assistant leaves with a shrug of her shoulders and "see, I could
> have told you that".
> If I'm measuring the wrong thing, please do tell me what I'm doing
> wrong, but otherwise I think a rethink is in order.
Again, how far did you lean the bicycle? When I perform this test it
responds as described above. The high side loses more tension than
the low side, but they both lose tension. Other spokes of the wheel
do not change audibly. In normal bicycling, riders climb hills
standing by leaning enough to make the high side spokes stand vertical
to the road. If you doubt this, I suggest a road test while sighting
down through the front hub.
I don't know how high the spoke tone went but I'll bet it is lower than
the tone of the rear spokes in the front wheel
carl...@comcast.net
jobst....@stanfordalumni.org wrote:
[snip]
>How far did you lean the bicycle? No doubt as the lean angle gets
>large, larger than when riding, it starts becoming more a side load on
>the wheel similar to pushing the rim sideways at the brake bridge.
[snip]
Dear Jobst,
What's a large lean-angle in degrees when riding?
And is it different for climbing a steep slope versus
sprinting on the level for the finish line?
I'm not arguing, just hoping that someone is going to find a
link to some article that explains how much a bicycle
actually tilts from side to side.
I understand that the tilt may differ for amateurs and pros.
(Or maybe it doesn't--that's one of the things that I'm
wondering about.)
I realize that tilt may vary widely according to purely
individual style. (That's another question--maybe we're not
nearly as unique as we like to think, or maybe some of us
wobble far more entertainingly than others.)
Joe Riel mentions some pictures, but didn't give any links.
He also has made some efforts to measure how far his top
tube sways, but all I can do is applaud his efforts and
wonder if he's normal, extra-steady, or Bronco Billy.
(You and I can appreciate how easily our own habits distort
our perceptions--you can't help thinking that mashing up
Alpine passes in high gears on a six-speed is normal, while
I assume that everyone would be happy riding along a river
with a 7-speed 53x11 at a glacial cadence.)
Carl Fogel
jobst....@stanfordalumni.org
>> Besides, spoke stress is not what the wheelbuilder wants to know,
>> since correct spoke tension is prescribed for a specific rim,
>> rather than stress in its spokes.
> That's true with modern lightweight rims and high quality spokes.
> It is not universally true, however, and at the time John was doing
> the research that led to this article lower quality spokes were the
> norm, as were heavier, stronger rims.
> Back in the '70s and early '80s, nipples pulling through the rim
> were exceedingly uncommon, and the usual cause of spoke breakage was
> insufficient spoke tension. Tensiometers were not generally
> available, and John provided a useful service by offering a way an
> inexperienced wheelbuilder could get some idea of correct spoke
> tension.
I am not aware of spoke failure caused by insufficient tension. How
does that occur and for what mechanical reason?
Not only is my recollection of failures different but I have a stack
of more than 20 worn out MA-2 rims, none of which have cracks around
spoke eyelets. These were wheels that I built to the maximum safe
tension that I arrived upon when I discovered that some people built
wheels with too high spoke tension and whose wheels warped under hard
braking, the only load that uniformly increases spoke tension in any
part of the wheel.
Cracked rims, in contrast, appeared suddenly with the arrival of hard
and thickly anodized rims, the most obvious one being the MA-40 that
is identical to the non-cracking MA-2 except for the anodizing. Other
brands that offered hard anodized rims also had cracking problems, so
much so that whole rims separated along the inner chamber, having
thinner walls than the braking surface. That caused the tire to
remain on the thicker walled outer portion and being without sockets,
the inner portion was left attached to the spokes.
We have not made progress in that department. Few rims today have
sockets that distribute spoke loads to both walls and some not even
eyelets, meanwhile anodizing is still used although more sparingly.
jobst....@stanfordalumni.org
>> Are you sure about your statement that heavier, stronger rims were
>> the norm in the past (70s-early 80s)? It seems to me that the norm
>> in the 70s was a 270-350g rim,
>> Maybe my impression is the result of involvement in racing, tubular
>> rims, and bike shops that catered to racing cyclists. Maybe the
>> trend was different for clincher rims- they do seem to have gotten
>> lighter over the same period as they have come to be considered an
>> alternative to tubulars for "serious" cyclists.
> I think you've analyzed it correctly- tubular rims from days of yore
> were 250 to 350 grams, where most clincher rims were in the
> 500-gram-ish range. Nowadays, clincher rims in the 400 gram range
> are relatively common, while you'll have a hard time finding *any*
> tubular rims in a shop now.
The MA-2 rime remained unchanged through many years and with the use
of steel sockets and eyelets, weighed 480g while the almost identical
Torelli Master weighed 440g.
> Nashbar has some:
> http://www.nashbar.com/profile.cfm?brand=1317&sku=12561
> Yikes! 480 grams!
> http://www.nashbar.com/profile.cfm?brand=1317&sku=12555
Memory fades. It was Sheeren Weltmeister tubular rims (with wooden
inserts at each spoke to support tension) that weighed 230g and were
so fragile that they could take little tension and therefore collapsed
easily. Gustav Scheeren was a champion German sprinter of the 1920's.
Marvin
> Marvin Meredith writes:
>
> >>>>> On the road, however, the rear wheel is not displaced by
> >>>>> laterally loading the rim at the brake, which minimizes the
> >>>>> required force. The forces involved may require substantial
> >>>>> changes in spoke tension. That has to be shown.
>
> >>>> I agree and that is easily done. I suggest that you stand on the
> >>>> pedals and lean the bicycle to the side, as one does when
> >>>> pedaling on a hill, and do a tone test. You'll find that there
> >>>> is no significant change in tension of the upper spokes (the ones
> >>>> near the brake pad).
>
> > But as any good student of the Bicycle Wheel will know, tension
> > changes from ground contact only affect the bottom few spokes in any
> > significant manner. Surely it's those we ought to be measuring?
>
> I think I said that and you quote that below at "Oops".
Yes, we should measure the lower spokes, which I was doing anyway. You
said ten lines above there's no change in tension of the *upper*
spokes. Was this a completely unrelated fact, or were you trying to
confuse the issue?
> >>>> This is a false visualization of spoke stresses similar to "the
> >>>> wheel hangs from the top spokes" scenario. The change lies in
> >>>> the amount of slackening of left and right spokes at the ground
> >>>> contact zone.
>
> >>> I'm not convinced here. I'll accept (as in the Bicycle Wheel)
> >>> that spokes lose tension from a radial load, so the spokes at the
> >>> bottom of a wheel are the lightest loaded. I'll also accept that
> >>> lateral loading has no overall effect, only to change the balance
> >>> between left and right side spokes. This obviously means one side
> >>> increases in tension relative to the other.
>
> >> Oops! No, that is not the case. One side loses more tension than
> >> the other and only at the ground contact zone. You needn't take
> >> this on faith. It is easy to test as has been explained.
>
> > Yes, I just tested it and got exactly the result I expected - higher
> > tension in the spokes nearest the ground. Perhaps we're measuring
> > different things, so I'll describe this in painstaking detail.
>
> How far did you lean the bicycle? No doubt as the lean angle get
> large, larger than when riding, it starts becoming more a side load on
> the wheel similar to pushing the rim sideways at the brake bridge.
At the risk of sounding like jim beam, first you were loudly asserting
that there was *no* change in tension due to lateral loads, which we
now know isn't the case. Now it's lateral loads encountered during
"normal" riding. When I tell you my "normal" riding style involves a
fair amount of bike sway, especially during sprinting, doubtless you'll
further "clarify" your position.
In point of fact, the above test was done leaning the bike as far as I
"normally" would, although propping up against a wall is never the most
accurate gauge of such things. I'll try sighting through the front hub
when I go to work (which should have been five minutes ago).
...the what spokes in what? :-)
jobst....@stanfordalumni.org
>>>>>>> On the road, however, the rear wheel is not displaced by
>>>>>>> laterally loading the rim at the brake, which minimizes the
>>>>>>> required force. The forces involved may require substantial
>>>>>>> changes in spoke tension. That has to be shown.
>>>>>> I agree and that is easily done. I suggest that you stand on
>>>>>> the pedals and lean the bicycle to the side, as one does when
>>>>>> pedaling on a hill, and do a tone test. You'll find that there
>>>>>> is no significant change in tension of the upper spokes (the
>>>>>> ones near the brake pad).
>>> But as any good student of the Bicycle Wheel will know, tension
>>> changes from ground contact only affect the bottom few spokes in
>>> any significant manner. Surely it's those we ought to be
>>> measuring?
>> I think I said that and you quote that below at "Oops".
> Yes, we should measure the lower spokes, which I was doing anyway.
> You said ten lines above there's no change in tension of the *upper*
> spokes. Was this a completely unrelated fact, or were you trying to
> confuse the issue?
No, because the suggestion was made that the upper spokes are the ones
that increase in tension. To prove that contention, the writer
suggested pushing the rim sideways manually until it touched the brake
pad. The point is that up there, even with off axis loading, no
significant (audible) increase in tension occurs. That's where this
thread began. The proponents of this tack have changed the approach
since that venue collapsed.
I WHAT! I said nothing of the kind. I said at the brake bridge there
was no change. Let's not change horses in the middle of the wheel.
The spokes pointing rearward in the front wheel when braking. You can
see the effect of this in diagrams in "the Bicycle Wheel".
jim beam
> Marvin Meredith writes:
>
>
>>>>>>>>On the road, however, the rear wheel is not displaced by
>>>>>>>>laterally loading the rim at the brake, which minimizes the
>>>>>>>>required force. The forces involved may require substantial
>>>>>>>>changes in spoke tension. That has to be shown.
>
>
>>>>>>>I agree and that is easily done. I suggest that you stand on
>>>>>>>the pedals and lean the bicycle to the side, as one does when
>>>>>>>pedaling on a hill, and do a tone test. You'll find that there
>>>>>>>is no significant change in tension of the upper spokes (the
>>>>>>>ones near the brake pad).
>
>
>>>>But as any good student of the Bicycle Wheel will know, tension
>>>>changes from ground contact only affect the bottom few spokes in
>>>>any significant manner. Surely it's those we ought to be
>>>>measuring?
>
>
>>>I think I said that and you quote that below at "Oops".
>
>
>>Yes, we should measure the lower spokes, which I was doing anyway.
>>You said ten lines above there's no change in tension of the *upper*
>>spokes. Was this a completely unrelated fact, or were you trying to
>>confuse the issue?
>
>
> No, because the suggestion was made that the upper spokes are the ones
> that increase in tension. To prove that contention, the writer
> suggested pushing the rim sideways manually until it touched the brake
> pad.
wow, that's a shameless distortion.
> The point is that up there, even with off axis loading, no
> significant (audible) increase in tension occurs. That's where this
> thread began. The proponents of this tack have changed the approach
> since that venue collapsed.
eh?
jobst, even you admit that on climbing, rims can rub brake pads. *by
definition*, that means that the upper part of the wheel is experiencing
lateral load, resulting from a much larger lateral loading at the bottom
part of the wheel. yet you now go back and twist your words in
avoidance??? that's ridiculous.
jim beam
> Sheldon Brown writes:
>
>
>>>Besides, spoke stress is not what the wheelbuilder wants to know,
>>>since correct spoke tension is prescribed for a specific rim,
>>>rather than stress in its spokes.
>
>
>>That's true with modern lightweight rims and high quality spokes.
>>It is not universally true, however, and at the time John was doing
>>the research that led to this article lower quality spokes were the
>>norm, as were heavier, stronger rims.
>
>
>>Back in the '70s and early '80s, nipples pulling through the rim
>>were exceedingly uncommon, and the usual cause of spoke breakage was
>>insufficient spoke tension. Tensiometers were not generally
>>available, and John provided a useful service by offering a way an
>>inexperienced wheelbuilder could get some idea of correct spoke
>>tension.
>
>
> I am not aware of spoke failure caused by insufficient tension. How
> does that occur and for what mechanical reason?
eh? so why do you advocate tension "as high as the rim can bear"?
>
> Not only is my recollection of failures different but I have a stack
> of more than 20 worn out MA-2 rims, none of which have cracks around
> spoke eyelets. These were wheels that I built to the maximum safe
> tension
which is what? this is the 3rd time of asking. it's important that you
answer what tension you use because spoke tension /does/ have a material
impact on rim cracking.
> that I arrived upon when I discovered that some people built
> wheels with too high spoke tension and whose wheels warped under hard
> braking, the only load that uniformly increases spoke tension in any
> part of the wheel.
>
> Cracked rims, in contrast, appeared suddenly with the arrival of hard
> and thickly anodized rims, the most obvious one being the MA-40 that
> is identical to the non-cracking MA-2 except for the anodizing.
but jobst, as we've discussed before, many times, the cracking does
/not/ emanate from the the radial cracks associated with anodizing.
cracking is almost always circumferential, or axial with the extrusion
axis, the weakest vein of the material. these cracks are frequently
/not/ centered on the spoke hole, therefore they /cannot/ be initiating
at the radial cracks resulting from any anodizing cracks. to argue
otherwise displays a /fundamental/ misunderstanding of the situation -
anodizing is NOT the cause!
time the ma40's arrival with cassette hubs and their more extreme dish,
and you have a strange coincidence, yes? mount an ma2 on a cassette hub
and it cracks, as has been cited here. an even more strange
coincidence? yet you still don't care to acknowledge anything that
disagrees with you.
the only "evidence" you've ever cited for "anodizing causes rim
cracking" is a dye penetrant test, something that is laughably
inappropriate - it only tells you existence, not cause. why do you
bluster and blow about stuff like this when all you're doing is
confirming that you don't know what you're talking about? most
engineers have to study basic materials science - where were you for
those classes? why would you want to hold forth on subjects you don't
know, get it wrong, and /still/ keep plowing on about it? what
intellectual issues do you have that prevents you from even basic
research on the internet or visiting a decent library? there's the
mechanics institute library in san francisco, a short hop for you - you
really need to make a visit some time. it's free.
> Other
> brands that offered hard anodized rims also had cracking problems, so
> much so that whole rims separated along the inner chamber, having
> thinner walls than the braking surface. That caused the tire to
> remain on the thicker walled outer portion and being without sockets,
> the inner portion was left attached to the spokes.
symptoms, not cause. typical jobstian "bait the fabricated edifice with
a meagre fact" argument. an entertaining device to be sure, but hardly
appropriate for an "expert" anxious to demonstrate competence.
Joe Riel
> What pictures?
> Do they show a sequence of side-to-side sway?
The ones you mentioned (I think) at smallchainring.com,
when looking for sideshots. Some of the photos were front views.
No sequences, so we cannot ascertain the maximum lean, however,
none showed any significant lean.
>
> I've been wondering about how much actual side-tilt there is
> and whether I've been fooled by the shoulder-drop when the
> rider sort of twists and curls down (rather than to the
> side) toward the foot at the bottom of the stroke.
I believe that there is a lot less lean than people imagine.
Certainly one can exaggerate the lean, but when you are
doing it naturally, the bike doesn't move all that much.
Certainly the total horizontal motion of the top tube is
less than 12 inches (side to side).
Joe
SocSecTr...@earthlink.net
Jay Beattie wrote:
> My PX10 came with Monthlery Pros, which were a 400 gram tubular
> rim -- the same weight as my current Aeorohead OC clincher rim.
> Other models of the Monthlery were lighter, though. The relative
> light rims on the PX10 made little difference in the grand scheme
> of things because of the (felt like) three pound Simplex seat
> post, Pivo stem and boat-anchor Ideal leather saddle.
This was at a time when the standard Peugeot ten speeds came with steel
rims (clinchers, of course), steel cottered cranks and, IIRC, steel
handlebars.
Sheldon Brown
>>Back in the '70s and early '80s, nipples pulling through the rim
>>were exceedingly uncommon, and the usual cause of spoke breakage was
>>insufficient spoke tension. Tensiometers were not generally
>>available, and John provided a useful service by offering a way an
>>inexperienced wheelbuilder could get some idea of correct spoke
>>tension.
>
Jobst Brandt wrote:
>
> I am not aware of spoke failure caused by insufficient tension. How
> does that occur and for what mechanical reason?
Fatigue. I know you seem to think that the only cause of spoke fatigue
is inadequate stress relief. You may even be correct in this, and these
failures may result from the fact that it's impossible to stress relieve
spokes that have too low an initial tension.
I do know that back before you explained the metallurgy of stress relief
in spokes, wheels with low tension and stainless spokes suffered fatigue
failure much more often than wheels with higher tension.
(Despite an imperfect understanding of the microstructural results of
stress relieving, it is a practice that good wheelbuilders have followed
for many decades, even if they called it by another name.)
Sheldon "Relief" Brown
+------------------------------------------------------+
| What signifies knowing the names if you know not |
| the natures of things? -- Benjamin Franklin |
+------------------------------------------------------+
Sheldon Brown
>>John could be clearer in his use of the word "tension." He uses this
>>not in the sense of absolute tension (pounds or dynes) but tension per
>>cross-sectional area (PSI or dynes/cm2.)
>
Luns Tee asked:
> Why not use the proper word for this instead of fuzzying up the
> meaning of another? Force per unit area is stress.
I can't speak for John, but the reason I didn't use the term "stress" is
'cause I didn't think of it.
Sheldon "Stress Free" Brown
+-------------------------------------------------------------+
| Want of care does us more damage than want of knowledge. |
| -- Benjamin Franklin |
+-------------------------------------------------------------+