spoke tension

Ron Ruff said:

jim beam said:

how about you address the point of the posting: "...the wheel can
support loads only to the point where its spokes become loose. at this
point the wheel will collapse." jobst brandt. "the book". 3rd edition.

Maybe an exaggeration... but close to the truth. When spokes become
slack they no longer provide support to the rim, so the rim is sort of
on it's own. It's stiffness and strength and resistance to buckling
drops a lot.

finally, someone that gets it!

indeed, spokes /do/ support the rim. but the support of the spokes
relies on tension. that tension is "borrowed" from the rim. and
tension in excess of that required to prevent spoke slackening comes at
the cost of bringing the rim closer to yield than is necessary, /and/ at
the cost of increasing fatigue propensity.

and wheel strength does not increase as spoke tension increases. and a
wheel will not collapse because a few spokes are slack.

jim beam said:

Gary Young said:

jim beam said:

Gary Young wrote:
> On Fri, 20 Jul 2007 18:53:12 -0700, jim beam wrote:
>
>> Gary Young wrote:
>>> On Thu, 19 Jul 2007 05:54:37 -0700, jim beam wrote:
>>>
>>>> Gary Young wrote:
>>>>> On Wed, 18 Jul 2007 21:43:17 -0700, jim beam wrote:
>>>>>
>>>>>> Johnny Sunset aka Tom Sherman wrote:
>>>>>>> "jim beam" ? wrote:
>>>>>>>> Johnny Sunset aka Tom Sherman wrote:
>>>>>>>>> "jim beam" ? wrote:
>>>>>>>>>> ...
>>>>>>>>>> in your book, you also argue that rims collapse as soon as spokes go
>>>>>>>>>> slack go slack....
>>>>>>>>>> http://www.flickr.com/photos/38636024@N00/417157612/
>>>>>>>>> How far did you ride on that wheel?
>>>>>>>>>
>>>>>>>> as far as i could without the tensiometer falling off... wise guy.
>>>>>>>>
>>>>>>>> how about you address the point of the posting: "...the wheel can
>>>>>>>> support loads only to the point where its spokes become loose. at
>>>>>>>> this point the wheel will collapse." jobst brandt. "the book". 3rd
>>>>>>>> edition.
>>>>>>> Would "jim beam's" wheel with missing spokes collapse if ridden? If so,
>>>>>>> JB is right (for all practical purposes) and jb is wrong.
>>>>>>>
>>>>>> i've ridden a slack spoked wheel so see if it works. and it does. and
>>>>>> you can google this group for my experience with a friend's slack spoked
>>>>>> mtb wheel. you should try it too. your only problem is spoke nipples
>>>>>> unscrewing.
>>>>> So, once again the photograph you offered as proof turns out to be no sort
>>>>> of proof at all.
>>>> so you're saying that pic is a fabrication? it's holding my full body
>>>> weight. i am the heaviest thing in my house. what more do you want
>>>> gary?
>>> As I've said elsewhere, what I would expect before taking your claims
>>> seriously is an experiment that actually tests Jobst's claims. That would
>>> require subjecting your wheel to a significant side load. You haven't done
>>> that.
>>>
>>>> of course, you /could/ bother to replicate my experiment rather
>>>> than simply bellyache, but that's not an armchair exercise.
>>> Replicate? You haven't done an experiment that tests Jobst's claims.
>>> What's to replicate? And no, I won't be the one to do the initial
>>> experiment for you. I don't risk expensive equipment on the word of an
>>> anonymous internet crank.
>> hmmm. i put my money where my mouth is and i post the results. what do
>> you do? [other than just bleat from the sidelines of course.]
>>
> In other words, you conducted an irrelevant experiment that doesn't
> address the issue of side loads, but you want an "A" for effort anyway.
eh? evidence contradicting an argument based on fundamental
misunderstanding is "irrelevant"?

good luck to you out there in the real world gary - you need it!

>> and that's a rhetorical question.

Is your position that side loads play no role in wheel failures?

no, my position is that you don't understand enough to be even asking
that question!

How do side loads figure in your explanation of wheel failure? (Please
spare me the ad hominem arguments; my understanding or lack of it
is irrelevant to whether you can answer a perfectly straightforward
question.)

Also, since you agree that side loads do play a part in wheel failures,
why didn't you subject your experimental wheel to a side load?

jim beam said:

how about you address the point of the posting: "...the wheel can
support loads only to the point where its spokes become loose. at this
point the wheel will collapse." jobst brandt. "the book". 3rd edition.

Maybe an exaggeration... but close to the truth. When spokes become
slack they no longer provide support to the rim, so the rim is sort of
on it's own. It's stiffness and strength and resistance to buckling
drops a lot.

jim beam said:

Gary Young said:

jim beam said:

Gary Young wrote:
> On Sat, 21 Jul 2007 09:03:50 -0700, jim beam wrote:
>
>> Gary Young wrote:
>>> On Fri, 20 Jul 2007 18:53:12 -0700, jim beam wrote:
>>>
>>>> Gary Young wrote:
>>>>> On Thu, 19 Jul 2007 05:54:37 -0700, jim beam wrote:
>>>>>
>>>>>> Gary Young wrote:
>>>>>>> On Wed, 18 Jul 2007 21:43:17 -0700, jim beam wrote:
>>>>>>>
>>>>>>>> Johnny Sunset aka Tom Sherman wrote:
>>>>>>>>> "jim beam" ? wrote:
>>>>>>>>>> Johnny Sunset aka Tom Sherman wrote:
>>>>>>>>>>> "jim beam" ? wrote:
>>>>>>>>>>>> ...
>>>>>>>>>>>> in your book, you also argue that rims collapse as soon as spokes go
>>>>>>>>>>>> slack go slack....
>>>>>>>>>>>> http://www.flickr.com/photos/38636024@N00/417157612/
>>>>>>>>>>> How far did you ride on that wheel?
>>>>>>>>>>>
>>>>>>>>>> as far as i could without the tensiometer falling off... wise guy.
>>>>>>>>>>
>>>>>>>>>> how about you address the point of the posting: "...the wheel can
>>>>>>>>>> support loads only to the point where its spokes become loose. at
>>>>>>>>>> this point the wheel will collapse." jobst brandt. "the book". 3rd
>>>>>>>>>> edition.
>>>>>>>>> Would "jim beam's" wheel with missing spokes collapse if ridden? If so,
>>>>>>>>> JB is right (for all practical purposes) and jb is wrong.
>>>>>>>>>
>>>>>>>> i've ridden a slack spoked wheel so see if it works. and it does. and
>>>>>>>> you can google this group for my experience with a friend's slack spoked
>>>>>>>> mtb wheel. you should try it too. your only problem is spoke nipples
>>>>>>>> unscrewing.
>>>>>>> So, once again the photograph you offered as proof turns out to be no sort
>>>>>>> of proof at all.
>>>>>> so you're saying that pic is a fabrication? it's holding my full body
>>>>>> weight. i am the heaviest thing in my house. what more do you want
>>>>>> gary?
>>>>> As I've said elsewhere, what I would expect before taking your claims
>>>>> seriously is an experiment that actually tests Jobst's claims. That would
>>>>> require subjecting your wheel to a significant side load. You haven't done
>>>>> that.
>>>>>
>>>>>> of course, you /could/ bother to replicate my experiment rather
>>>>>> than simply bellyache, but that's not an armchair exercise.
>>>>> Replicate? You haven't done an experiment that tests Jobst's claims.
>>>>> What's to replicate? And no, I won't be the one to do the initial
>>>>> experiment for you. I don't risk expensive equipment on the word of an
>>>>> anonymous internet crank.
>>>> hmmm. i put my money where my mouth is and i post the results. what do
>>>> you do? [other than just bleat from the sidelines of course.]
>>>>
>>> In other words, you conducted an irrelevant experiment that doesn't
>>> address the issue of side loads, but you want an "A" for effort anyway.
>> eh? evidence contradicting an argument based on fundamental
>> misunderstanding is "irrelevant"?
>>
>> good luck to you out there in the real world gary - you need it!
>>
>>
>>>> and that's a rhetorical question.
> Is your position that side loads play no role in wheel failures?

no, my position is that you don't understand enough to be even asking
that question!

How do side loads figure in your explanation of wheel failure? (Please
spare me the ad hominem arguments; my understanding or lack of it
is irrelevant to whether you can answer a perfectly straightforward
question.)

Also, since you agree that side loads do play a part in wheel failures,
why didn't you subject your experimental wheel to a side load?

what part of "i've ridden a slack spoked wheel so see if it works. and
it does." is unclear?

You said you didn't ride the experimental wheel in the photograph because
you didn't want the tensiometer to fall off. I take it that you're now
referring to some other incident in which you rode a slack wheel. That at
least is some progress -- you've implicitly admitted that the experiment
you photographed is irrelevant to the issue of side loads. In order to
answer my question, you had to appeal to evidence outside of the
experiment in the photograph.

When you rode the slack spoked wheel, did you subject it to significant
side loads? Please explain what they were.

Also, please answer my question about what place side loads play in your
theoretical account of wheel failure.

Ron Ruff said:

jim beam said:

how about you address the point of the posting: "...the wheel can
support loads only to the point where its spokes become loose. at this
point the wheel will collapse." jobst brandt. "the book". 3rd edition.

Maybe an exaggeration... but close to the truth. When spokes become
slack they no longer provide support to the rim, so the rim is sort of
on it's own. It's stiffness and strength and resistance to buckling
drops a lot.

I wouldn't go so far as to call it an exaggeration until "jim beam"
supplies a page reference (he's ignored my request for that). Jobst is
usually careful to say that a slack wheel is vulnerable primarily to side
loads. "Jim beam" may well have quoted selectively to obscure the context.
Furthermore, even if Jobst exaggerated at one point, it's simply sophistry
to ignore the qualifying remarks he makes at other points in the book.

On Sat, 21 Jul 2007 12:52:51 -0500, Gary Young <[email hidden]>

Quoted message said:

Ron Ruff said:

jim beam said:

how about you address the point of the posting: "...the wheel can
support loads only to the point where its spokes become loose. at this
point the wheel will collapse." jobst brandt. "the book". 3rd edition.

Maybe an exaggeration... but close to the truth. When spokes become
slack they no longer provide support to the rim, so the rim is sort of
on it's own. It's stiffness and strength and resistance to buckling
drops a lot.

I wouldn't go so far as to call it an exaggeration until "jim beam"
supplies a page reference (he's ignored my request for that). Jobst is
usually careful to say that a slack wheel is vulnerable primarily to side
loads. "Jim beam" may well have quoted selectively to obscure the context.
Furthermore, even if Jobst exaggerated at one point, it's simply sophistry
to ignore the qualifying remarks he makes at other points in the book.

Dear Gary,

You're interested in textual references? How nice! There's nothing
like a good discussion of the vexing problem of how to cut and paste
together a version of Hamlet that combines the various quartos
(published without Shakespeare's consent during his lifetime) with the
version found in the First Folio of 1623, published also without his
consent, seven years after his death. Unlike Macbeth, for which we
have only the First Folio version and thus no scholarly debate--

Oh, you're only interested in "The Bicycle Wheel"?

Well, there are three English editions of Jobst's book, plus one in
German that we will ignore.

The two later editions add a little material and subtract a little
material, but they mainly reword things, often sentence by sentence.

This inch-by-inch rephrasing makes it horribly difficult to find a
particular passage.

Even worse from a scholarly point of view, the theoretical material in
the first part is often repeated in the second practical part, so you
may be looking at the wrong end of the book.

Frequently the reader hits an it's-explained-elsewhere comment, but
there's no page number given and no index.

(A scanned and searchable version obtained from unethical sources
helps immensely. Anyone willing to profit from piracy is welcome to
ask me to search for a phrase from the 3rd edition, since it only
takes a few moments.)

To be fair, Jobst was no more writing for scholars than Shakespeare
was, and Jim faces a hideous scholarly task if he wants to footnote
properly.

***

Here's the first edition (1981, 1983), illustrated by Sherry
Sheffield-Boulton, p. 78:

SPOKE TENSION

The correct tension for a wheel must be a balance between rim strength
and wheel stability. The spokes should be as tight as the rim permits
for maxium strength. However, for practical reasonss the spokes should
be slightly looser than this because at the maximum tension, the
failure of one spoke may destroy the rim.

***

Here's the second edition (1981, 1983, 1988, 7th printing 1990),
illustrated by Sherry Sheffield Boulton (no dash), p. 76:

SPOKE TENSION

The correct tension for a wheel is a balance between rim strength and
wheel stability. For greatest strength, spokes should be as tight as
the rim permits. In practice, however, spokes should be slightly
looser because when they are at the limit, failure of a single spoke
can severely deform the rim.

***

And here's the third edition (1993), illustrated by Sherry Sheffield
(no Boulton), page 71:

SPOKE TENSION

With tensioned wires as spokes, the wheel can support loads only to
the point where its spokes become loose. At this point the wheel will
collapse. Therefore, for greatest strength, spokes must be as tight as
the rim permits. . . .

[skip the rest of the paragraph and jump ~80 words to where the next
sentence has been moved]

In practice, however, spokes should be slightly looser than the
maximum the rim can sustain, because at maximum tension, failure of a
single spoke can severely deform the rim.

***

I defy anyone to find a more trivial example of the trivial changes
between the three editions than the illustrator's name (which may have
been far from trivial to her).

Anyway, there's the text and the page numbers and some explanation why
quoting from various editions of "The Bicycle Wheel" is something that
only the truly pedantic can enjoy.

Cheers,

Carl Fogel

jim beam said:

Ron Ruff wrote:

Quoted message said:

Quoted message said:

Maybe an exaggeration... but close to the truth. When spokes become
slack they no longer provide support to the rim, so the rim is sort of
on it's own. It's stiffness and strength and resistance to buckling
drops a lot.

finally, someone that gets it!

indeed, spokes /do/ support the rim. but the support of the spokes
relies on tension. that tension is "borrowed" from the rim. and
tension in excess of that required to prevent spoke slackening comes at
the cost of bringing the rim closer to yield than is necessary, /and/ at
the cost of increasing fatigue propensity.

and wheel strength does not increase as spoke tension increases. and a
wheel will not collapse because a few spokes are slack.

What's to get? This (as usual) is a tempest in a teapot. Everyone
realizes that a wheel with too loose spokes is weak and everyone
realizes that a wheel with too tight spokes is weak (will taco if you
breathe on it). Therefore, in between there is some ideal spoke tension.

You may set this tension with a tensiometer per the maker's spec., or
you can use Jobst's method *if* you don't have a tensiometer and you
have rims like the ones he mentions.

You tediously go on & on about this as if Jobst doesn't believe in
tensiometers (he did design one) or recommends the alternative approach
in an unqualified way (which he didn't).

With regard to strength, there are at least 2 common modes of wheel
failure: flat spotting and taco'ing. You don't specify which you're
talking about.

For spoke tension to affect flat spotting by "borrowing" from rim
compression, you'd have to calculate the static compressive stress and
compare that to yield stress. If static was 10% of yield, then a 20%
change in spoke tension would only translate into a 2% yield difference
(presuming wheel yield was initiated by compressive yield, something
you'd also have to prove). For spoke tension to be a factor, static rim
compressive stress would have to be a significant fraction of yield. I
doubt that, but if you have the numbers, I'm all ears.

To know static compressive stress, you'd have to know static force (in
Jobst's book) and rim cross section area. You have those, right?

For taco failures things get a lot more complicated. I'm not aware of an
out of plane loading model that would apply, the radial model is
complicated enough. But if you have insight, please share.

[email hidden] wrote:

<snip quoted text>

Quoted message said:

I defy anyone to find a more trivial example of the trivial changes
between the three editions than the illustrator's name (which may have
been far from trivial to her).

Anyway, there's the text and the page numbers and some explanation why
quoting from various editions of "The Bicycle Wheel" is something that
only the truly pedantic can enjoy.

Stop it Carl, you're spoiling a good fight that could go on for months!

After this I shall be building my wheels with half the spokes tensioned
to the max, a quarter untensioned, 2/5s missing completely and the rest
perpendicular to the lines of load!

Hmmmm...no ones mentioned the Citreon Mono Spoke yet...

Peter Cole said:

jim beam said:

Ron Ruff wrote:

Quoted message said:

Quoted message said:

Maybe an exaggeration... but close to the truth. When spokes become
slack they no longer provide support to the rim, so the rim is sort of
on it's own. It's stiffness and strength and resistance to buckling
drops a lot.

finally, someone that gets it!

indeed, spokes /do/ support the rim. but the support of the spokes
relies on tension. that tension is "borrowed" from the rim. and
tension in excess of that required to prevent spoke slackening comes
at the cost of bringing the rim closer to yield than is necessary,
/and/ at the cost of increasing fatigue propensity.

and wheel strength does not increase as spoke tension increases. and
a wheel will not collapse because a few spokes are slack.

What's to get? This (as usual) is a tempest in a teapot. Everyone
realizes that a wheel with too loose spokes is weak and everyone
realizes that a wheel with too tight spokes is weak (will taco if you
breathe on it). Therefore, in between there is some ideal spoke tension.

like "stress relief", the practice is qualitatively right, but the
theory is way off base. you /do/ indeed need sufficient spoke tension
for a trouble free wheel, but the reason is to avoid spoke nipples
unscrewing and spoke elbow fatigue. neither are static wheel strength.

Quoted message said:

You may set this tension with a tensiometer per the maker's spec., or
you can use Jobst's method *if* you don't have a tensiometer and you
have rims like the ones he mentions.

maybe for an old fashioned rim, but for a modern higher profile
[stiffer] rim, that method gives spoke tension too high which in turn
causes rims to crack.

Quoted message said:

You tediously go on & on about this as if Jobst doesn't believe in
tensiometers (he did design one)

because we do have his word for it. he's said repeatedly that you don't
need a tensiometer, simply use spoke tension "as high as the rim can bear".

and he didn't finish the math on his tensiometer. look at the formula
in his book. he thinks that tensiometer readings are unaffected by
spoke stiffness - which is untrue.

Quoted message said:

or recommends the alternative approach
in an unqualified way (which he didn't).

With regard to strength, there are at least 2 common modes of wheel
failure: flat spotting and taco'ing. You don't specify which you're
talking about.

either. a rim yield when any point in it exceeds the requite stress.
the metal doesn't care whether that stress is from application or
superposition. when high enough, it yields. tension or compression.
end of story.

Quoted message said:

For spoke tension to affect flat spotting by "borrowing" from rim
compression, you'd have to calculate the static compressive stress and
compare that to yield stress. If static was 10% of yield, then a 20%
change in spoke tension would only translate into a 2% yield difference
(presuming wheel yield was initiated by compressive yield, something
you'd also have to prove). For spoke tension to be a factor, static rim
compressive stress would have to be a significant fraction of yield. I
doubt that, but if you have the numbers, I'm all ears.

buckling is close to yield, and spoke tension "as high as the rim can
bear" is that limit.

Quoted message said:

To know static compressive stress, you'd have to know static force (in
Jobst's book) and rim cross section area. You have those, right?

what good will knowing the force be if you don't know the strength of
the materials?

Quoted message said:

For taco failures things get a lot more complicated. I'm not aware of an
out of plane loading model that would apply, the radial model is
complicated enough. But if you have insight, please share.

don't seek refuge in complexity. each element is simple.

here's the bottom line: the calculations in the book compute load.
that's all fine and dandy, but load doesn't tell you a damned thing
about strength. this is the point you keep missing and which jobst
doesn't address.

Peter Cole said:

Quoted message said:

Quoted message said:

Maybe an exaggeration... but close to the truth. When spokes
become slack they no longer provide support to the rim, so the rim
is sort of on it's own. It's stiffness and strength and
resistance to buckling drops a lot.

Quoted message said:

Quoted message said:

finally, someone that gets it!

Quoted message said:

Quoted message said:

indeed, spokes /do/ support the rim. but the support of the spokes
relies on tension. that tension is "borrowed" from the rim. and
tension in excess of that required to prevent spoke slackening
comes at the cost of bringing the rim closer to yield than is
necessary, /and/ at the cost of increasing fatigue propensity.

Quoted message said:

Quoted message said:

and wheel strength does not increase as spoke tension increases.
and a wheel will not collapse because a few spokes are slack.

Quoted message said:

What's to get? This (as usual) is a tempest in a teapot. Everyone
realizes that a wheel with too loose spokes is weak and everyone
realizes that a wheel with too tight spokes is weak (will taco if
you breathe on it). Therefore, in between there is some ideal spoke
tension.

Quoted message said:

You may set this tension with a tensiometer per the maker's spec.,
or you can use Jobst's method *if* you don't have a tensiometer and
you have rims like the ones he mentions.

Quoted message said:

You tediously go on & on about this as if Jobst doesn't believe in
tensiometers (he did design one) or recommends the alternative
approach in an unqualified way (which he didn't).

Quoted message said:

With regard to strength, there are at least 2 common modes of wheel
failure: flat spotting and taco'ing. You don't specify which you're
talking about.

Quoted message said:

For spoke tension to affect flat spotting by "borrowing" from rim
compression, you'd have to calculate the static compressive stress
and compare that to yield stress. If static was 10% of yield, then
a 20% change in spoke tension would only translate into a 2% yield
difference (presuming wheel yield was initiated by compressive
yield, something you'd also have to prove). For spoke tension to be
a factor, static rim compressive stress would have to be a
significant fraction of yield. I doubt that, but if you have the
numbers, I'm all ears.

Flat spots are caused typically by landing on a relatively (to the
tire cross section) smooth place, like coming down onto smooth
pavement from too high a jump, or hitting a v-groove (open culvert
type) at too high a speed. If this doesn't bottom the tire, the bead
of the rim will not be damaged but the rim, as a bridge, will yield
and not return from the flattened condition entirely.

Considering how the wheel supports loads, this is the standard way
taken beyond the limit of rim strength. Unfortunately, these limiting
conditions are no longer addressed in road rims today so we ride on
fragile, low spoke count rims that crack at the suggestion of use and
get flat spots readily.

Quoted message said:

To know static compressive stress, you'd have to know static force
(in Jobst's book) and rim cross section area. You have those,
right?

The limit of tension for good rims was the tension at which the
compressive force caused buckling; the tension at which the rim begins
to pretzel. This effect is not sudden or large, the rim being held in
line by the spokes that are not near yield and have a large elastic
modulus. The amount of yield for this to be visible is microscopic,
the ratio of bending to length change being enormous as most people
have gathered from the coat hanger test. You can easily bend a coat
hanger manually but you can't even begin to stretch it by hand.

Quoted message said:

For taco failures things get a lot more complicated. I'm not aware
of an out of plane loading model that would apply, the radial model
is complicated enough. But if you have insight, please share.

To do this loosen the spokes to near zero tension and see how much
more the wheel deflects when a weight is hung on it, as shown in the
tying and soldering defection test in "thew Bicycle Wheel".

Jobst Brandt

carlfogel said:

On Sat, 21 Jul 2007 12:52:51 -0500, Gary Young <[email hidden]>

Quoted message said:

Ron Ruff said:

On Jul 18, 7:02 am, jim beam <[email hidden]> wrote:
> how about you address the point of the posting: "...the wheel can
> support loads only to the point where its spokes become loose. at this
> point the wheel will collapse." jobst brandt. "the book". 3rd edition.

Maybe an exaggeration... but close to the truth. When spokes become
slack they no longer provide support to the rim, so the rim is sort of
on it's own. It's stiffness and strength and resistance to buckling
drops a lot.

I wouldn't go so far as to call it an exaggeration until "jim beam"
supplies a page reference (he's ignored my request for that). Jobst is
usually careful to say that a slack wheel is vulnerable primarily to side
loads. "Jim beam" may well have quoted selectively to obscure the context.
Furthermore, even if Jobst exaggerated at one point, it's simply sophistry
to ignore the qualifying remarks he makes at other points in the book.

Dear Gary,

You're interested in textual references? How nice! There's nothing
like a good discussion of the vexing problem of how to cut and paste
together a version of Hamlet that combines the various quartos
(published without Shakespeare's consent during his lifetime) with the
version found in the First Folio of 1623, published also without his
consent, seven years after his death. Unlike Macbeth, for which we
have only the First Folio version and thus no scholarly debate--

Oh, you're only interested in "The Bicycle Wheel"?

Well, there are three English editions of Jobst's book, plus one in
German that we will ignore.

The two later editions add a little material and subtract a little
material, but they mainly reword things, often sentence by sentence.

This inch-by-inch rephrasing makes it horribly difficult to find a
particular passage.

Even worse from a scholarly point of view, the theoretical material in
the first part is often repeated in the second practical part, so you
may be looking at the wrong end of the book.

Frequently the reader hits an it's-explained-elsewhere comment, but
there's no page number given and no index.

(A scanned and searchable version obtained from unethical sources
helps immensely. Anyone willing to profit from piracy is welcome to
ask me to search for a phrase from the 3rd edition, since it only
takes a few moments.)

To be fair, Jobst was no more writing for scholars than Shakespeare
was, and Jim faces a hideous scholarly task if he wants to footnote
properly.

***

Here's the first edition (1981, 1983), illustrated by Sherry
Sheffield-Boulton, p. 78:

SPOKE TENSION

The correct tension for a wheel must be a balance between rim strength
and wheel stability. The spokes should be as tight as the rim permits
for maxium strength. However, for practical reasonss the spokes should
be slightly looser than this because at the maximum tension, the
failure of one spoke may destroy the rim.

***

Here's the second edition (1981, 1983, 1988, 7th printing 1990),
illustrated by Sherry Sheffield Boulton (no dash), p. 76:

SPOKE TENSION

The correct tension for a wheel is a balance between rim strength and
wheel stability. For greatest strength, spokes should be as tight as
the rim permits. In practice, however, spokes should be slightly
looser because when they are at the limit, failure of a single spoke
can severely deform the rim.

***

And here's the third edition (1993), illustrated by Sherry Sheffield
(no Boulton), page 71:

SPOKE TENSION

With tensioned wires as spokes, the wheel can support loads only to
the point where its spokes become loose. At this point the wheel will
collapse. Therefore, for greatest strength, spokes must be as tight as
the rim permits. . . .

[skip the rest of the paragraph and jump ~80 words to where the next
sentence has been moved]

In practice, however, spokes should be slightly looser than the
maximum the rim can sustain, because at maximum tension, failure of a
single spoke can severely deform the rim.

***

I defy anyone to find a more trivial example of the trivial changes
between the three editions than the illustrator's name (which may have
been far from trivial to her).

Anyway, there's the text and the page numbers and some explanation why
quoting from various editions of "The Bicycle Wheel" is something that
only the truly pedantic can enjoy.

Cheers,

Carl Fogel

Carl,
Thanks for supplying the quotation, but I do think you exaggerate the
difficulties "jim beam" faced. He said in an earlier post that he took the
quotation from the third edition and should have been able to supply a
page.

In any event, judging from the discussion taking place between Jobst and
Peter Cole right now, I'm getting the impression that I've once again
allowed my zeal to expose jim beam's nonsense take me beyond my knowledge.
I'm going to try to be humble for awhile.

Peter Cole said:

jim beam wrote:
<snipped same old [censored]>

Quoted message said:

here's the bottom line: the calculations in the book compute load.
that's all fine and dandy, but load doesn't tell you a damned thing
about strength. this is the point you keep missing and which jobst
doesn't address.

Bottom line is you don't have the numbers.

bottom line, you're still missing the point. you show me how a load
calc demonstrates strength [or better yet, how increasing load increases
strength], /then/ we can talk numbers.

Peter Cole said:

jim beam said:

Peter Cole said:

jim beam wrote:
<snipped same old [censored]>

> here's the bottom line: the calculations in the book compute load.
> that's all fine and dandy, but load doesn't tell you a damned thing
> about strength. this is the point you keep missing and which jobst
> doesn't address.

Bottom line is you don't have the numbers.

bottom line, you're still missing the point. you show me how a load
calc demonstrates strength [or better yet, how increasing load
increases strength], /then/ we can talk numbers.

Sorry, I have no interest in that.

evidently. shame.

On Sat, 21 Jul 2007 15:42:39 -0500, Gary Young <[email hidden]>

Quoted message said:

carlfogel said:

On Sat, 21 Jul 2007 12:52:51 -0500, Gary Young <[email hidden]>

Quoted message said:

On Sat, 21 Jul 2007 10:39:04 -0700, Ron Ruff wrote:

> On Jul 18, 7:02 am, jim beam <[email hidden]> wrote:
>> how about you address the point of the posting: "...the wheel can
>> support loads only to the point where its spokes become loose. at this
>> point the wheel will collapse." jobst brandt. "the book". 3rd edition.
>
> Maybe an exaggeration... but close to the truth. When spokes become
> slack they no longer provide support to the rim, so the rim is sort of
> on it's own. It's stiffness and strength and resistance to buckling
> drops a lot.

I wouldn't go so far as to call it an exaggeration until "jim beam"
supplies a page reference (he's ignored my request for that). Jobst is
usually careful to say that a slack wheel is vulnerable primarily to side
loads. "Jim beam" may well have quoted selectively to obscure the context.
Furthermore, even if Jobst exaggerated at one point, it's simply sophistry
to ignore the qualifying remarks he makes at other points in the book.

Dear Gary,

You're interested in textual references? How nice! There's nothing
like a good discussion of the vexing problem of how to cut and paste
together a version of Hamlet that combines the various quartos
(published without Shakespeare's consent during his lifetime) with the
version found in the First Folio of 1623, published also without his
consent, seven years after his death. Unlike Macbeth, for which we
have only the First Folio version and thus no scholarly debate--

Oh, you're only interested in "The Bicycle Wheel"?

Well, there are three English editions of Jobst's book, plus one in
German that we will ignore.

The two later editions add a little material and subtract a little
material, but they mainly reword things, often sentence by sentence.

This inch-by-inch rephrasing makes it horribly difficult to find a
particular passage.

Even worse from a scholarly point of view, the theoretical material in
the first part is often repeated in the second practical part, so you
may be looking at the wrong end of the book.

Frequently the reader hits an it's-explained-elsewhere comment, but
there's no page number given and no index.

(A scanned and searchable version obtained from unethical sources
helps immensely. Anyone willing to profit from piracy is welcome to
ask me to search for a phrase from the 3rd edition, since it only
takes a few moments.)

To be fair, Jobst was no more writing for scholars than Shakespeare
was, and Jim faces a hideous scholarly task if he wants to footnote
properly.

***

Here's the first edition (1981, 1983), illustrated by Sherry
Sheffield-Boulton, p. 78:

SPOKE TENSION

The correct tension for a wheel must be a balance between rim strength
and wheel stability. The spokes should be as tight as the rim permits
for maxium strength. However, for practical reasonss the spokes should
be slightly looser than this because at the maximum tension, the
failure of one spoke may destroy the rim.

***

Here's the second edition (1981, 1983, 1988, 7th printing 1990),
illustrated by Sherry Sheffield Boulton (no dash), p. 76:

SPOKE TENSION

The correct tension for a wheel is a balance between rim strength and
wheel stability. For greatest strength, spokes should be as tight as
the rim permits. In practice, however, spokes should be slightly
looser because when they are at the limit, failure of a single spoke
can severely deform the rim.

***

And here's the third edition (1993), illustrated by Sherry Sheffield
(no Boulton), page 71:

SPOKE TENSION

With tensioned wires as spokes, the wheel can support loads only to
the point where its spokes become loose. At this point the wheel will
collapse. Therefore, for greatest strength, spokes must be as tight as
the rim permits. . . .

[skip the rest of the paragraph and jump ~80 words to where the next
sentence has been moved]

In practice, however, spokes should be slightly looser than the
maximum the rim can sustain, because at maximum tension, failure of a
single spoke can severely deform the rim.

***

I defy anyone to find a more trivial example of the trivial changes
between the three editions than the illustrator's name (which may have
been far from trivial to her).

Anyway, there's the text and the page numbers and some explanation why
quoting from various editions of "The Bicycle Wheel" is something that
only the truly pedantic can enjoy.

Cheers,

Carl Fogel

Carl,
Thanks for supplying the quotation, but I do think you exaggerate the
difficulties "jim beam" faced. He said in an earlier post that he took the
quotation from the third edition and should have been able to supply a
page.

In any event, judging from the discussion taking place between Jobst and
Peter Cole right now, I'm getting the impression that I've once again
allowed my zeal to expose jim beam's nonsense take me beyond my knowledge.
I'm going to try to be humble for awhile.

Dear Gary,

To be fair to Jim, you've got the page number and two previous
variations of the same section that you asked for when you wrote:

"I wouldn't go so far as to call it an exaggeration until 'jim beam'
supplies a page reference (he's ignored my request for that). Jobst is
usually careful to say that a slack wheel is vulnerable primarily to
side loads. 'Jim beam' may well have quoted selectively to obscure the
context."

"Furthermore, even if Jobst exaggerated at one point, it's simply
sophistry to ignore the qualifying remarks he makes at other points in
the book."

It looks like an accurate, in-context quote. There is no mention of
side loads on those pages. If people want to argue that Jim Beam is
missing something, then it's up to them to provide the quote or
context that they imply he is concealing.

So far, they haven't.

I'm not concerned with the physics, just the claims from various
obviously prejudiced posters that someone who quotes specifically and
accurately and apparently in context is not doing so, without any
explanation or equally specific quotations refuting the point. Perhaps
less irritated replies would have explained things better.

I appreciate your frank admission that you may have let your zeal to
squabble with Jim get the best of you--I hope that I can admit as much
when I find myself in a similar situation.

Cheers,

Carl Fogel

aka Carl Fogel said:

...
I appreciate your frank admission that you may have let your zeal to
squabble with Jim get the best of you--I hope that I can admit as much
when I find myself in a similar situation....

Past history indicates...

--
Tom Sherman - Holstein-Friesland Bovinia
The weather is here, wish you were beautiful

--
Posted via a free Usenet account from http://www.teranews.com

jim beam wrote:
<snipped same old [censored]>

Quoted message said:

here's the bottom line: the calculations in the book compute load.
that's all fine and dandy, but load doesn't tell you a damned thing
about strength. this is the point you keep missing and which jobst
doesn't address.

Bottom line is you don't have the numbers.

jim beam said:

Peter Cole said:

jim beam wrote:
<snipped same old [censored]>

Quoted message said:

here's the bottom line: the calculations in the book compute load.
that's all fine and dandy, but load doesn't tell you a damned thing
about strength. this is the point you keep missing and which jobst
doesn't address.

Bottom line is you don't have the numbers.

bottom line, you're still missing the point. you show me how a load
calc demonstrates strength [or better yet, how increasing load increases
strength], /then/ we can talk numbers.

Sorry, I have no interest in that.

In article
<[email hidden]>,

Quoted message said:

There's nothing
like a good discussion of the vexing problem of how to cut and paste
together a version of Hamlet that combines the various quartos
(published without Shakespeare's consent during his lifetime) with the

His consent is irrelevant since everybody knows
Edward de Vere, 17th Earl of Oxford wrote the plays.

Quoted message said:

version found in the First Folio of 1623, published also without his
consent, seven years after his death.

--
Michael Press

On Sun, 22 Jul 2007 05:22:01 GMT, Michael Press <[email hidden]>

Quoted message said:

His consent is irrelevant since everybody knows
Edward de Vere, 17th Earl of Oxford wrote the plays.

You're wrong... I didn't know that.

Then again, I think Shakespeare sucks, so it's not surprising!

jim beam said:

Quoted message said:

http://www.jimbeam.com/beam/default.aspx?writes:

Quoted message said:

Quoted message said:

>>> Could someone recommend the proper spoke tension for a rear wheel
>>> built with a Velocity Aerohead OC rim?

Quoted message said:

Quoted message said:

>> JB says tension as high as the rim will bear without taking a
>> "taco" or "potato chip" shape; however, jb says tension only as
>> high as the manufacturer's recommendation, or the rim will crack
>> around the spoke hole.

Quoted message said:

Quoted message said:

>> LET THE BATTLE BEGIN!

Quoted message said:

Quoted message said:

> That's not really what Jobst says. It's what jim beam says Jobst
> says, which are usually two (often very) different things. I guess
> you didn't read the book, either.

Quoted message said:

Quoted message said:

"as high as the rim can bear" is what jobst says on this group.

Quoted message said:

Quoted message said:

"spokes must be as tight as the rim permits" is what he says in "the
book". [3rd edition.]

Quoted message said:

Quoted message said:

either way, he equates increasing spoke tension with increasing
wheel strength: "a wheel with spoke tension near the limit of rim
strength can support large loads easily" - which is untrue,
misleading and reveals gross misunderstanding.

Quoted message said:

I think such statements need a bit of evidence to be credible.

Quoted message said:

A wire spoked bicycle wheel can carry loads up to the point where its
spokes become slack from compression as they pass the load point on
the road. The looser the spokes the more easily this occurs and
conversely the tighter the spoke the less this occurs.

as discussed on several prior occasions, you are only considering the
spokes, not the rim. increasing spoke tension increases circumferential
rim compression. but you miss the point that as the rim's compression
rises, its load capacity decreases.

let's assume an aluminum beam has the same tensile strength as it does
compression. let's say that it yields at [pick a number] +/- 100Mpa.
in plain bending, the compressive side yields at the same time as the
tensile side - when this limit is reached. now, compress the beam
longitudinally at say 50Mpa, i.e. superimpose a stress on it. the
tensile side of the beam can now support 100 + 50 = 150Mpa before yield.
but the compressive side can only support 100 - 50 = 50Mpa. so if i
bend it now, the beam will start to yield supporting only half the load
it did before.

with materials with no tensile strength like concrete, you "borrow" from
the material's [ample] compressive strength to give it pseudo tensile
strength. but with a material as strong in compression as tension, like
an aluminum bike rim, that's simply counter-productive.

in your book, you also argue that rims collapse as soon as spokes go
slack go slack....http://www.flickr.com/photos/38636024@N00/417157612/

writing a book is one thing. understanding what to put in it is quite
another.

Quoted message said:

I have ridden many 100k miles with wheels tensioned as described
without needing to re-true them or to replace cracked rims. These
have been socketed tubular rims (Fiamme, Super Champion, and Mavic)
and Super Champion "Gentleman" and Mavic MA-2 clincher rims. I still
ride the latter as do most of my fellow riders, ones who do not see
themselves as professional like racers..

Quoted message said:

When riding rough roads such as described in rec.bicycles.rides "Last
chance road", I and my bikie friends wonder if the light weight "with
it" crowd ever experience roads that are demanding on 36-spoke wheels.

Quoted message said:

http://tinyurl.com/2uc6tb

Quoted message said:

Dings in rims also come from insufficient inflation, a parallel to
insufficient spoke tension in supporting loads.

Quoted message said:

http://geocities.com/rayhosler/slideshow.html

Quoted message said:

Ride bike!

red herring.

This is the dilemma that many people have:

They want advise on wheels and they look for an expert's opinion.
There are two guys who respond. One says: "wheel X with Y
characteristics is ideal." The other one says: "wheel P with Q
characteristics is ideal" both offer contradictory info with some
technical and inaccessible explanations for non engineers.

so, people have to decide which poster to believe. Poster XY has
published a book that is often referred to by bicycle people who
regularly build and sell wheels, shop owners, cyclists, and other
sport aficionados. Poster XY also post pictures in which he rides
with XY wheels in dirt roads, endless hills, tours of Europe, and post
pictures of his friends riding XY wheels with the same
characteristics. Poster XY is a regular consultant for Avocet, and
gets hired to test the products. In other words, poster XY has
established a solid reputation as an expert in the field and can site
a history of expertise and product testing. Moreover, Poster XY
doesn't appear to be affiliated or to receive compensation for many of
the ideas or products that he endorses.

Now, Poster PQ post under a pseudonym. So we don't know if he has ever
published anything. The regular wheel builders in the community and
the shop owners do not seem to endorse him. We don't know if he rides
what he claims to support and has in no established credibility.

It is possible that PQs arguments are all valid. But, for those who
lack expertise to understand the explanations, credibility is
important. It is like reading a research paper with no notes and
references vs one in which all the referred information is noted,
referenced and backed.
When people disagree with poster PQ, he becomes verbally abusive in
frustration.

If poster's PQ arguments were valid, it is very unfortunate. His lack
of credibility prevents his knowledge from being disseminated. Is
there any way that poster PQ can back up his arguments by citing the
millions of wheels that he has built for friends and customers? Can ha
document the millions of miles that he has biked on his wheels? Can
he cite companies that have consulted with him and referred to his
ideas?

I think that poster PQ needs to find a way to document that his ways
have resulted in thousands of wheels being built, thousands of miles
being ridden and a following from other aficionados. If he could build
that kind of reputation, then we could have more interesting
exchanges.

I, myself have built wheels following poster XY with great success. In
fact, being a fatso and a cheapskate, I like XY's ideas, because they
are cost effective and durable and provide many miles of riding. In
fact, my bikes have inexpensive boring looking wheels a la XY. Would I
build wheels following PQ's advise? Not now, based on his current
reputation.

Just my thoughts,

Andres