Yet another broken spoke

[jim beam]

Ben C wrote:
> On 2007-09-05, clare at snyder.on.ca <> wrote:
> [...]
>> Loose spokes also wear the holes in the hubs - and wear the spokes
>> where they go through the hub.
>
> I hadn't thought of that. That would explain the phenomenon (loose
> spokes breaking) in a way that's consistent with my understanding of
> Jobst's earlier suggestion that there is a bit of clearance down there.
>
> I thought the reasoning was: the spoke can't easily be bent since it
> isn't firmly held in the hub hole but free to wobble a bit. But if it's
> wobbling up and down it can wear and that can initiate fatigue.
>
>> I've replaced numerous spokes that were worn half way through before
>> breaking (and some that had not yet broken)
>
> Maybe this is something datakoll's practice of putting Teflon wax in the
> hub holes before you put the spokes in could help with.

he lives in a hot salty climate, so in his case, it's more likely that
it mitigates corrosion or stress corrosion. sticky **** that retains
grit sure isn't going to do a thing to mitigate wear.

 

[Peter Cole]

jim beam wrote:
> [email protected] wrote:

>> What is bending the elbow in your perception?
>
> simple loading!!! the spoke elbow is offset from the spoke axis, thus
> is it subject to bending - by definition!!!

If the spoke elbow is fully supported on its inside radius it can't
bend. By definition!!!!!!!!


> except that it /is/ being bent back and forth more, simply because it's
> interleaved.

Do the math. How much force (tension) does it take to fully straighten a
clothesline with a 5lb weight in the center?

 

[Ben C]

On 2007-09-05, jim beam <[email protected]> wrote:
> Ben C wrote:
>> On 2007-09-05, clare at snyder.on.ca <> wrote:
>> [...]
>>> Loose spokes also wear the holes in the hubs - and wear the spokes
>>> where they go through the hub.
>>
>> I hadn't thought of that. That would explain the phenomenon (loose
>> spokes breaking) in a way that's consistent with my understanding of
>> Jobst's earlier suggestion that there is a bit of clearance down there.
>>
>> I thought the reasoning was: the spoke can't easily be bent since it
>> isn't firmly held in the hub hole but free to wobble a bit. But if it's
>> wobbling up and down it can wear and that can initiate fatigue.
>>
>>> I've replaced numerous spokes that were worn half way through before
>>> breaking (and some that had not yet broken)
>>
>> Maybe this is something datakoll's practice of putting Teflon wax in the
>> hub holes before you put the spokes in could help with.
>
> he lives in a hot salty climate, so in his case, it's more likely that
> it mitigates corrosion or stress corrosion. sticky **** that retains
> grit sure isn't going to do a thing to mitigate wear.

Good point. IIRC he may also have reported this was a way to get more
life out of generic spokes. I don't know if those are the galvanized
kind, but also some kinds of Chinese "stainless" steel do rust in little
spots. I know because I've seen it happen to teaspoons.

 

[Peter Cole]

Ben C wrote:
> On 2007-09-04, [email protected] <[email protected]> wrote:

>> But the other spoke can only drop from 100 pounds of pre-tension down
>> to 0. After it loses only 100 pounds of tension, it just rattles.
>
> I get it! Thanks.
>
> Of course whether it does rattle harmlessly or flex horribly, rapidly
> fatiguing itself to death, is another matter.

It could only "flex horribly" (or at all) if the spoke was bowed. Even
in that case, you'd have to consider where the flex occurred vs where
the spokes broke. The "flexing horribly" speculation also needs to
consider the actual amount of rim deflection which bounds the degree of
"horribleness".

A worst case scenario would be where the spoke elbow angle did not match
the angle of the spoke hole to flange. In that case, fluctuations in
tension could cause elbow bending when the overall tension wasn't high
enough to keep the spoke fully supported. To have that happen the
angular mismatch would have had to survived the initial wheel tensioning
and stress relief. If a wheel was built with low tension and not stress
relieved, and a spoke subsequently became loose enough to lose support
at the elbow, it might bend enough to fatigue rapidly, but I would
consider this to be the consequence of a bad initial build rather than a
loose spoke per se.

 

[jim beam]

Peter Cole wrote:
> jim beam wrote:
>> [email protected] wrote:
>
>>> What is bending the elbow in your perception?
>>
>> simple loading!!! the spoke elbow is offset from the spoke axis, thus
>> is it subject to bending - by definition!!!
>
> If

"if"??

> the spoke elbow is fully supported on its inside radius it can't
> bend. By definition!!!!!!!!

but it's not. so you're bullshitting.


>
>
>> except that it /is/ being bent back and forth more, simply because
>> it's interleaved.
>
> Do the math. How much force (tension) does it take to fully straighten a
> clothesline with a 5lb weight in the center?
>

false example - the usual peter cole deceit.

 

[jim beam]

Peter Cole wrote:
> Ben C wrote:
>> On 2007-09-04, [email protected] <[email protected]> wrote:
>
>>> But the other spoke can only drop from 100 pounds of pre-tension down
>>> to 0. After it loses only 100 pounds of tension, it just rattles.
>>
>> I get it! Thanks.
>>
>> Of course whether it does rattle harmlessly or flex horribly, rapidly
>> fatiguing itself to death, is another matter.
>
> It could only "flex horribly" (or at all) if the spoke was bowed. Even
> in that case, you'd have to consider where the flex occurred vs where
> the spokes broke. The "flexing horribly" speculation also needs to
> consider the actual amount of rim deflection which bounds the degree of
> "horribleness".
>
> A worst case scenario would be where the spoke elbow angle did not match
> the angle of the spoke hole to flange. In that case, fluctuations in
> tension could cause elbow bending when the overall tension wasn't high
> enough to keep the spoke fully supported. To have that happen the
> angular mismatch would have had to survived the initial wheel tensioning
> and stress relief. If a wheel was built with low tension and not stress
> relieved, and a spoke subsequently became loose enough to lose support
> at the elbow, it might bend enough to fatigue rapidly, but I would
> consider this to be the consequence of a bad initial build rather than a
> loose spoke per se.

wow! how to admit something you've previously denied, while phrasing it
as further denial!!! quite masterful.

 

[Peter Cole]

jim beam wrote:
> Peter Cole wrote:
>> jim beam wrote:
>>> [email protected] wrote:
>>
>>>> What is bending the elbow in your perception?
>>>
>>> simple loading!!! the spoke elbow is offset from the spoke axis,
>>> thus is it subject to bending - by definition!!!
>>
>> If
>
> "if"??
>
>> the spoke elbow is fully supported on its inside radius it can't bend.
>> By definition!!!!!!!!
>
> but it's not. so you're bullshitting.

It is if you've built your wheel right.


>>> except that it /is/ being bent back and forth more, simply because
>>> it's interleaved.
>>
>> Do the math. How much force (tension) does it take to fully straighten
>> a clothesline with a 5lb weight in the center?
>>
>
> false example - the usual peter cole deceit.

No, the interleaving force is in the middle of the spoke, like the
clothesline. Consider the vectors.

 

[Peter Cole]

jim beam wrote:
> Peter Cole wrote:
>> Ben C wrote:
>>> On 2007-09-04, [email protected] <[email protected]> wrote:
>>
>>>> But the other spoke can only drop from 100 pounds of pre-tension down
>>>> to 0. After it loses only 100 pounds of tension, it just rattles.
>>>
>>> I get it! Thanks.
>>>
>>> Of course whether it does rattle harmlessly or flex horribly, rapidly
>>> fatiguing itself to death, is another matter.
>>
>> It could only "flex horribly" (or at all) if the spoke was bowed. Even
>> in that case, you'd have to consider where the flex occurred vs where
>> the spokes broke. The "flexing horribly" speculation also needs to
>> consider the actual amount of rim deflection which bounds the degree
>> of "horribleness".
>>
>> A worst case scenario would be where the spoke elbow angle did not
>> match the angle of the spoke hole to flange. In that case,
>> fluctuations in tension could cause elbow bending when the overall
>> tension wasn't high enough to keep the spoke fully supported. To have
>> that happen the angular mismatch would have had to survived the
>> initial wheel tensioning and stress relief. If a wheel was built with
>> low tension and not stress relieved, and a spoke subsequently became
>> loose enough to lose support at the elbow, it might bend enough to
>> fatigue rapidly, but I would consider this to be the consequence of a
>> bad initial build rather than a loose spoke per se.
>
> wow! how to admit something you've previously denied, while phrasing it
> as further denial!!! quite masterful.

Only in your world. In the first paragraph, I was referring to the spoke
bending along its whole length, the second only at the elbow -- in case
that wasn't clear.

I think the burden is on you to explain how the spoke elbow is
unsupported (or how it can bend if it isn't).

 

[[email protected]]

Ben C? writes:

>> [...]
>> Loose spokes also wear the holes in the hubs - and wear the spokes
>> where they go through the hub.

> I hadn't thought of that. That would explain the phenomenon (loose
> spokes breaking) in a way that's consistent with my understanding of
> Jobst's earlier suggestion that there is a bit of clearance down
> there.

You'll have to show some evidence of loose spokes wearing thin at the
elbow. That has not been observed by anyone building wheels around
here and I've been watching this sort of thing for more years than
most. Spoke failures are from residual stress and stress
concentrations, not loose spokes or flexing from interleaving.

Flexing from interleaving (assuming the wheel was reasonably true) is
no greater with loose spokes than with tight ones, and probably less,
there being less force involved. Besides, if that were the source of
failure, then non-interleaved or radial spokes would be more durable,
as would tangential spoking, where spoke crossings are father from the
flange and have a minuscule angle.

> I thought the reasoning was: the spoke can't easily be bent since it
> isn't firmly held in the hub hole but free to wobble a bit. But if
> it's wobbling up and down it can wear and that can initiate fatigue.

But it doesn't because even becoming slack does not cause the contact
area to wear, there being no contact.

>> I've replaced numerous spokes that were worn half way through before
>> breaking (and some that had not yet broken)

That is pure imagination to put it mildly. Where are the readers
who detest exaggeration now?

> Maybe this is something datakoll's practice of putting Teflon wax in the
> hub holes before you put the spokes in could help with.

Bicycling is full of snake oil. Remember how a while back it was the
stem jam nut that caused stem separations from inner tubes? Well that
manufacturing run is gone now and we don't hear of it any more, but
there were many who believed the jam nut fable religiously in spite of
proof to the contrary (a manually tightened jam nut becomes loose when
the tire is inflated, showing that separation force is inflation
pressure, not the nut.) Now its spoke wear that causes loose spokes
to fail!

Jobst Brandt

 

[[email protected]]

Ben C? writes:

>>>> Loose spokes also wear the holes in the hubs - and wear the
>>>> spokes where they go through the hub.

>>> I hadn't thought of that. That would explain the phenomenon
>>> (loose spokes breaking) in a way that's consistent with my
>>> understanding of Jobst's earlier suggestion that there is a bit of
>>> clearance down there.

>>> I thought the reasoning was: the spoke can't easily be bent since
>>> it isn't firmly held in the hub hole but free to wobble a bit.
>>> But if it's wobbling up and down it can wear and that can initiate
>>> fatigue.

>>>> I've replaced numerous spokes that were worn half way through
>>>> before breaking (and some that had not yet broken)

>>> Maybe this is something datakoll's practice of putting Teflon wax
>>> in the hub holes before you put the spokes in could help with.

>> he lives in a hot salty climate, so in his case, it's more likely
>> that it mitigates corrosion or stress corrosion. sticky **** that
>> retains grit sure isn't going to do a thing to mitigate wear.

> Good point. IIRC he may also have reported this was a way to get
> more life out of generic spokes. I don't know if those are the
> galvanized kind, but also some kinds of Chinese "stainless" steel do
> rust in little spots. I know because I've seen it happen to
> teaspoons.

You needn't fly your kite on every breeze that comes along. Remember,
it's the jam nut on valve stems that caused stem separations about a
year ago, information that was brought to this newsgroup by the same
folks who say spokes break from low tension.

Jobst Brandt

 

[Ben C]

On 2007-09-05, [email protected] <[email protected]> wrote:
> Ben C? writes:
>
>>> [...]
>>> Loose spokes also wear the holes in the hubs - and wear the spokes
>>> where they go through the hub.
>
>> I hadn't thought of that. That would explain the phenomenon (loose
>> spokes breaking) in a way that's consistent with my understanding of
>> Jobst's earlier suggestion that there is a bit of clearance down
>> there.
>
> You'll have to show some evidence of loose spokes wearing thin at the
> elbow. That has not been observed by anyone building wheels around
> here

Do people build with the spokes too loose around there?

> and I've been watching this sort of thing for more years than most.
> Spoke failures are from residual stress and stress concentrations, not
> loose spokes or flexing from interleaving.

I believe those are possible causes. But I am not as sure as you that
they are the main or only causes.

> Flexing from interleaving (assuming the wheel was reasonably true) is
> no greater with loose spokes than with tight ones, and probably less,
> there being less force involved. Besides, if that were the source of
> failure, then non-interleaved or radial spokes would be more durable,
> as would tangential spoking, where spoke crossings are father from the
> flange and have a minuscule angle.
>
>> I thought the reasoning was: the spoke can't easily be bent since it
>> isn't firmly held in the hub hole but free to wobble a bit. But if
>> it's wobbling up and down it can wear and that can initiate fatigue.
>
> But it doesn't because even becoming slack does not cause the contact
> area to wear, there being no contact.
>
>>> I've replaced numerous spokes that were worn half way through before
>>> breaking (and some that had not yet broken)
>
> That is pure imagination to put it mildly.

How are you so sure that what Clare is describing cannot possibly have
occurred? I see no particular reason to doubt the report.

> Where are the readers who detest exaggeration now?
>
>> Maybe this is something datakoll's practice of putting Teflon wax in the
>> hub holes before you put the spokes in could help with.
>
> Bicycling is full of snake oil.

Ain't that the truth.

> Remember how a while back it was the stem jam nut that caused stem
> separations from inner tubes? Well that manufacturing run is gone now
> and we don't hear of it any more, but there were many who believed the
> jam nut fable religiously in spite of proof to the contrary (a
> manually tightened jam nut becomes loose when the tire is inflated,
> showing that separation force is inflation pressure, not the nut.)
> Now its spoke wear that causes loose spokes to fail!

There's no law that says all spokes have to fail for the same reason.

Here are a variety of possible reasons I can remember from RBT, in no
particular order, any accumulation of which any individual spoke might
suffer from:

1. Residual stress from manufacture
2. Retained stress in elbow from the build
3. Shank too long/bad spoke line
4. Surface finish of spokes poor (**** spokes)
5. Corrosion
6. Stress corrosion
7. Not enough tension, so spokes go slack
8. Rim flat spot causing slack spokes at the flat spot
9. Riding with too much weight on the bike so spokes go slack
10. Wear at the elbow

They all have varying degrees of supporting evidence, mostly indirect,
and of theoretical plausibility.

I have not seen anyone provide any convincing evidence that (1) and (2)
are the dominant factors to the total exclusion of all the others.
Personally I suspect (4), (7) and (9) are also quite a big part of the
picture.

 

[[email protected]]

Ben C? writes:

>>>> Loose spokes also wear the holes in the hubs - and wear the
>>>> spokes where they go through the hub.

>>> I hadn't thought of that. That would explain the phenomenon
>>> (loose spokes breaking) in a way that's consistent with my
>>> understanding of Jobst's earlier suggestion that there is a bit of
>>> clearance down there.

>> You'll have to show some evidence of loose spokes wearing thin at
>> the elbow. That has not been observed by anyone building wheels
>> around here

> Do people build with the spokes too loose around there?

Wheelsmith was the first, when they started using their Holland
Mechanics robot to build wheels. It was their bad experience with
wheels losing alignment that introduced SpokePrep, a glue to hide
loose spoking and imitated world wide by machine builders because the
machines could not distinguish spoke twist from spoke nipple rotating
(adjustment) causing an infinite loop of (non) corrections when wheels
got reasonably tight. Holland Mechanics said last year that they were
addressing this issue, one that is easily solved by a radial pneumatic
piston that unloads the spoke to be adjusted.

>> and I've been watching this sort of thing for more years than most.
>> Spoke failures are from residual stress and stress concentrations, not
>> loose spokes or flexing from interleaving.

> I believe those are possible causes. But I am not as sure as you that
> they are the main or only causes.

Yes, lets hear what you believe are the main causes.

>> Flexing from interleaving (assuming the wheel was reasonably true)
>> is no greater with loose spokes than with tight ones, and probably
>> less, there being less force involved. Besides, if that were the
>> source of failure, then non-interleaved or radial spokes would be
>> more durable, as would tangential spoking, where spoke crossings
>> are father from the flange and have a minuscule angle.

>>> I thought the reasoning was: the spoke can't easily be bent since
>>> it isn't firmly held in the hub hole but free to wobble a bit.
>>> But if it's wobbling up and down it can wear and that can initiate
>>> fatigue.

Only if you believe it is making solid contact, has grit between it
and the flange hole and doesn't slacken that force when wobbling,
wobbling caused by slackening. This scenario doesn't make sense.

>> But it doesn't because even becoming slack does not cause the
>> contact area to wear, there being no contact.

>>>> I've replaced numerous spokes that were worn half way through before
>>>> breaking (and some that had not yet broken)

>> That is pure imagination to put it mildly.

> How are you so sure that what Clare is describing cannot possibly have
> occurred? I see no particular reason to doubt the report.

As I mentioned, in theory it is not possible and in practice I have
never seen wear inside the spoke elbow in all the years I have been
involved with bicycles. I think if you read "the Bicycle Wheel" you
should be aware how thoroughly I have considered these effects.

>> Where are the readers who detest exaggeration now?

>>> Maybe this is something datakoll's practice of putting Teflon wax in the
>>> hub holes before you put the spokes in could help with.

>> Bicycling is full of snake oil.

> Ain't that the truth.

>> Remember how a while back it was the stem jam nut that caused stem
>> separations from inner tubes? Well that manufacturing run is gone now
>> and we don't hear of it any more, but there were many who believed the
>> jam nut fable religiously in spite of proof to the contrary (a
>> manually tightened jam nut becomes loose when the tire is inflated,
>> showing that separation force is inflation pressure, not the nut.)
>> Now its spoke wear that causes loose spokes to fail!

> There's no law that says all spokes have to fail for the same reason.

Oh, so what is the reason? I'll stick with residual stress as cause,
the explanation for which is explained in "the Bicycle Wheel".

> Here are a variety of possible reasons I can remember from RBT, in no
> particular order, any accumulation of which any individual spoke might
> suffer from:

> 1. Residual stress from manufacture
> 2. Retained stress in elbow from the build
> 3. Shank too long/bad spoke line
> 4. Surface finish of spokes poor (**** spokes)
> 5. Corrosion
> 6. Stress corrosion

> 8. Rim flat spot causing slack spokes at the flat spot
> 9. Riding with too much weight on the bike so spokes go slack
> 10. Wear at the elbow
> 7. Not enough tension, so spokes go slack

These are all the same issue and you slipped them in with valid
causes. However, that is what we are pursuing in this thread. How
does low tension cause spoke failure?

> They all have varying degrees of supporting evidence, mostly indirect,
> and of theoretical plausibility.

The first three have direct theoretical and practical evidence and
were resolved with the solutions I proposed. You can skip 4 through 5
for the spokes most of us use. As I have often mentioned, I have
wheels that went 300,000 miles with the same spokes (replacing rims)
when they wore out and no failures on the front wheel and outbound
right side spokes that got damaged by the chain.

> I have not seen anyone provide any convincing evidence that (1) and (2)
> are the dominant factors to the total exclusion of all the others.
> Personally I suspect (4), (7) and (9) are also quite a big part of the
> picture.

Basic material science spends great effort to make them credible,
through theory and lab testing. I think we have discussed this at
great length with only a "former metallurgist" claiming that new
materials resolved those causes rather than going back to short elbows
(that DT did) and to properly shape spokes and stress relieve after
building

Jobst Brandt

 

[jim beam]

Peter Cole wrote:
> jim beam wrote:
>> Peter Cole wrote:
>>> Ben C wrote:
>>>> On 2007-09-04, [email protected] <[email protected]> wrote:
>>>
>>>>> But the other spoke can only drop from 100 pounds of pre-tension down
>>>>> to 0. After it loses only 100 pounds of tension, it just rattles.
>>>>
>>>> I get it! Thanks.
>>>>
>>>> Of course whether it does rattle harmlessly or flex horribly, rapidly
>>>> fatiguing itself to death, is another matter.
>>>
>>> It could only "flex horribly" (or at all) if the spoke was bowed.
>>> Even in that case, you'd have to consider where the flex occurred vs
>>> where the spokes broke. The "flexing horribly" speculation also needs
>>> to consider the actual amount of rim deflection which bounds the
>>> degree of "horribleness".
>>>
>>> A worst case scenario would be where the spoke elbow angle did not
>>> match the angle of the spoke hole to flange. In that case,
>>> fluctuations in tension could cause elbow bending when the overall
>>> tension wasn't high enough to keep the spoke fully supported. To have
>>> that happen the angular mismatch would have had to survived the
>>> initial wheel tensioning and stress relief. If a wheel was built with
>>> low tension and not stress relieved, and a spoke subsequently became
>>> loose enough to lose support at the elbow, it might bend enough to
>>> fatigue rapidly, but I would consider this to be the consequence of a
>>> bad initial build rather than a loose spoke per se.
>>
>> wow! how to admit something you've previously denied, while phrasing
>> it as further denial!!! quite masterful.
>
> Only in your world. In the first paragraph, I was referring to the spoke
> bending along its whole length, the second only at the elbow -- in case
> that wasn't clear.
>
> I think the burden is on you to explain how the spoke elbow is
> unsupported (or how it can bend if it isn't).

er, the light gap between the hub and the spoke ought to be proof to
anyone whose intent is not to ******** and deceive...

 

[jim beam]

Peter Cole wrote:
> jim beam wrote:
>> Peter Cole wrote:
>>> jim beam wrote:
>>>> [email protected] wrote:
>>>
>>>>> What is bending the elbow in your perception?
>>>>
>>>> simple loading!!! the spoke elbow is offset from the spoke axis,
>>>> thus is it subject to bending - by definition!!!
>>>
>>> If
>>
>> "if"??
>>
>>> the spoke elbow is fully supported on its inside radius it can't
>>> bend. By definition!!!!!!!!
>>
>> but it's not. so you're bullshitting.
>
> It is if you've built your wheel right.
>
>
>>>> except that it /is/ being bent back and forth more, simply because
>>>> it's interleaved.
>>>
>>> Do the math. How much force (tension) does it take to fully
>>> straighten a clothesline with a 5lb weight in the center?
>>>
>>
>> false example - the usual peter cole deceit.
>
> No, the interleaving force is in the middle of the spoke, like the
> clothesline. Consider the vectors.

and we're discussing loosening and /angle/ increase. /you/ are trying
to deceive with /tension/ increase and straightening which can never be
achieved - as you well know.

 

[jim beam]

[email protected] wrote:
> Ben C? writes:
>
>>>>> Loose spokes also wear the holes in the hubs - and wear the
>>>>> spokes where they go through the hub.
>
>>>> I hadn't thought of that. That would explain the phenomenon
>>>> (loose spokes breaking) in a way that's consistent with my
>>>> understanding of Jobst's earlier suggestion that there is a bit of
>>>> clearance down there.
>
>>>> I thought the reasoning was: the spoke can't easily be bent since
>>>> it isn't firmly held in the hub hole but free to wobble a bit.
>>>> But if it's wobbling up and down it can wear and that can initiate
>>>> fatigue.
>
>>>>> I've replaced numerous spokes that were worn half way through
>>>>> before breaking (and some that had not yet broken)
>
>>>> Maybe this is something datakoll's practice of putting Teflon wax
>>>> in the hub holes before you put the spokes in could help with.
>
>>> he lives in a hot salty climate, so in his case, it's more likely
>>> that it mitigates corrosion or stress corrosion. sticky **** that
>>> retains grit sure isn't going to do a thing to mitigate wear.
>
>> Good point. IIRC he may also have reported this was a way to get
>> more life out of generic spokes. I don't know if those are the
>> galvanized kind, but also some kinds of Chinese "stainless" steel do
>> rust in little spots. I know because I've seen it happen to
>> teaspoons.
>
> You needn't fly your kite on every breeze that comes along. Remember,
> it's the jam nut on valve stems that caused stem separations about a
> year ago, information that was brought to this newsgroup by the same
> folks who say spokes break from low tension.

specious **** - rubber usage has /nothing/ to do with metal fatigue.

 

[jim beam]

>[email protected] wrote:
>> Ben C? writes:
>
<snip for clarity>

>> 1. Residual stress from manufacture
>> 2. Retained stress in elbow from the build
>> 3. Shank too long/bad spoke line
>> 4. Surface finish of spokes poor (**** spokes)
>> 5. Corrosion
>> 6. Stress corrosion
>
>> 8. Rim flat spot causing slack spokes at the flat spot
>> 9. Riding with too much weight on the bike so spokes go slack
>> 10. Wear at the elbow
>> 7. Not enough tension, so spokes go slack
>
> These are all the same issue

eh? no they're not. to pick just one, there's no way stress corrosion
can be confused with low cycle fatigue.


> and you slipped them in with valid
> causes. However, that is what we are pursuing in this thread. How
> does low tension cause spoke failure?

how about getting facts straight first?


>
>> They all have varying degrees of supporting evidence, mostly indirect,
>> and of theoretical plausibility.
>
> The first three have direct theoretical and practical evidence and
> were resolved with the solutions I proposed.

no they don't because "residual stress" is a red herring. the fatigue
initiation point is /not/ that of a high residual stress point - as
you'd know if you'd properly examined the fatigue fracture surfaces.


> You can skip 4 through 5
> for the spokes most of us use.

why? too inconvenient to discuss anything that can't be misconstrued in
the context of "residual stress".


> As I have often mentioned, I have
> wheels that went 300,000 miles with the same spokes

except for the spokes that you've replaced because they've failed...


> (replacing rims)
> when they wore out and no failures on the front wheel and outbound
> right side spokes that got damaged by the chain.

what happened to the excuse about having a stick in the spokes? any
other excuses or omissions?


>
>> I have not seen anyone provide any convincing evidence that (1) and (2)
>> are the dominant factors to the total exclusion of all the others.
>> Personally I suspect (4), (7) and (9) are also quite a big part of the
>> picture.
>
> Basic material science spends great effort to make them credible,
> through theory and lab testing.

indeed it does. and then it gets ignored by "engineers" that didn't
bother to research beyond the presumption that would allow them to claim
credit for the work of others.


> I think we have discussed this at
> great length with only a "former metallurgist" claiming that new
> materials resolved those causes rather than going back to short elbows
> (that DT did) and to properly shape spokes and stress relieve after
> building

truth is jobst, if you ever properly addressed the points i have had to
repeatedly raise with you, or ever bothered to read the cites i've given
you, went to the library and did your own homework, or even bought a
decent magnifier and bothered to examine fracture surfaces from actual
failures, you might, just might, be able to finally start to understand
a little about fatigue. instead, you continue to write suppositional
******** based on a shamefully poor grasp of the facts. if you even
understood the difference between materials that strain age and those
that don't, you might evidence some potential for understanding. but as
things stand, you continue to confirm the truth of the saying,
"ignorance can be cured, stupid is forever".

 

[Gary Young]

On Wed, 05 Sep 2007 20:56:58 -0700, jim beam wrote:

> Peter Cole wrote:
>> jim beam wrote:
>>> Peter Cole wrote:
>>>> Ben C wrote:
>>>>> On 2007-09-04, [email protected] <[email protected]> wrote:
>>>>
>>>>>> But the other spoke can only drop from 100 pounds of pre-tension down
>>>>>> to 0. After it loses only 100 pounds of tension, it just rattles.
>>>>>
>>>>> I get it! Thanks.
>>>>>
>>>>> Of course whether it does rattle harmlessly or flex horribly, rapidly
>>>>> fatiguing itself to death, is another matter.
>>>>
>>>> It could only "flex horribly" (or at all) if the spoke was bowed.
>>>> Even in that case, you'd have to consider where the flex occurred vs
>>>> where the spokes broke. The "flexing horribly" speculation also needs
>>>> to consider the actual amount of rim deflection which bounds the
>>>> degree of "horribleness".
>>>>
>>>> A worst case scenario would be where the spoke elbow angle did not
>>>> match the angle of the spoke hole to flange. In that case,
>>>> fluctuations in tension could cause elbow bending when the overall
>>>> tension wasn't high enough to keep the spoke fully supported. To have
>>>> that happen the angular mismatch would have had to survived the
>>>> initial wheel tensioning and stress relief. If a wheel was built with
>>>> low tension and not stress relieved, and a spoke subsequently became
>>>> loose enough to lose support at the elbow, it might bend enough to
>>>> fatigue rapidly, but I would consider this to be the consequence of a
>>>> bad initial build rather than a loose spoke per se.
>>>
>>> wow! how to admit something you've previously denied, while phrasing
>>> it as further denial!!! quite masterful.
>>
>> Only in your world. In the first paragraph, I was referring to the spoke
>> bending along its whole length, the second only at the elbow -- in case
>> that wasn't clear.
>>
>> I think the burden is on you to explain how the spoke elbow is
>> unsupported (or how it can bend if it isn't).
>
> er, the light gap between the hub and the spoke ought to be proof to
> anyone whose intent is not to ******** and deceive...

One can greatly reduce that gap by correcting the spoke line, something
you've previously said was unnecessary and even harmful. Has your position
changed?

 

[Joe Riel]

jim beam <[email protected]> writes:

> Peter Cole wrote:
>> I think the burden is on you to explain how the spoke elbow is
>> unsupported (or how it can bend if it isn't).
>
> er, the light gap between the hub and the spoke [...]

I don't see any light gap on my wheels. The outbound spokes
are fully bedded into the flange. The inbound spokes less so,
but still no visible gap.

--
Joe Riel

 

[jim beam]

Joe Riel wrote:
> jim beam <[email protected]> writes:
>
>> Peter Cole wrote:
>>> I think the burden is on you to explain how the spoke elbow is
>>> unsupported (or how it can bend if it isn't).
>> er, the light gap between the hub and the spoke [...]
>
> I don't see any light gap on my wheels. The outbound spokes
> are fully bedded into the flange. The inbound spokes less so,
> but still no visible gap.
>


http://www.flickr.com/photos/38636024@N00/1313347532/

xtr hub, d.t. spokes. gaps on heads in and heads out spokes. not an
atypical build i think you'll agree.

 

[Joe Riel]

jim beam <[email protected]> writes:

> Joe Riel wrote:
>> jim beam <[email protected]> writes:
>>
>>> Peter Cole wrote:
>>>> I think the burden is on you to explain how the spoke elbow is
>>>> unsupported (or how it can bend if it isn't).
>>> er, the light gap between the hub and the spoke [...]
>>
>> I don't see any light gap on my wheels. The outbound spokes
>> are fully bedded into the flange. The inbound spokes less so,
>> but still no visible gap.
>>
>
>
> http://www.flickr.com/photos/38636024@N00/1313347532/
>
> xtr hub, d.t. spokes. gaps on heads in and heads out spokes. not an
> atypical build i think you'll agree.
>

Here's a picture of my front hub. Hard to see the inbound spokes;
lighting wasn't ideal.

http://www.flickr.com/photos/12733237@N05/

--
Joe Riel