Spoke tension

Quoted message said:

Quoted message said:

This pushing-on-the-rim bit only
relaxes underside spokes . . .

Dear Jobst,

What do you predict will be shown by a spoke tension gauge when I try
this technique of leaning on a horizontal wheel with one hand on
either side of the rim?

That is, what will the top and bottom spokes do around the clock, with
my hands at 9 and 3 o'clock? Which will gain tension, which will lose
tension, and how much?

I haven't tried it yet, so this would be a good chance to test whether
theory predicts results.

Assuming a radially spoked front wheel, I'd expect that, for a small
displacement, the decrease in tension of the lower spokes is matched
by an increase in tension of the upper spokes. The largest changes
would be at the 3 and 9 o'oclock, the smallest at 6 and 12. Things
may be a bit more complicated for a 3x wheel.

--
Joe Riel

[email hidden] wrote:

"Many hubs have slightly cup shaped flanges that approximate the angle
of the average spoke to the rim so that outbound spokes do not have so
hard a time of aligning to the angle. These flanges are drilled, one
hole at a time by an NC machine that indexes at the appropriate
interval as the angled drill penetrates the flange normal to its
surface. "

Very cool. I didn't know that! I wonder how far back that goes?

Quoted message said:

Quoted message said:

This pushing-on-the-rim bit only relaxes underside spokes . . .

Quoted message said:

What do you predict will be shown by a spoke tension gauge when I
try this technique of leaning on a horizontal wheel with one hand on
either side of the rim?

I was wrong about the method. It increases spoke tension by about 20%
on a tight spoke. The bottom spoke at that location goes anywhere
from losing 3/4 of its tension to slack, depending on whether it is a
dished or symmetrical wheel. This was a rear wheel with sprockets up.

On a low tension wheel the upper spoke gains a larger but undefined
amount of tension relative to its starting point because that may be
practically slack. Of course the under side spoke goes slack with
even slight pressure, not having much to start with.

Quoted message said:

That is, what will the top and bottom spokes do around the clock,
with my hands at 9 and 3 o'clock? Which will gain tension, which
will lose tension, and how much?

Quoted message said:

I haven't tried it yet, so this would be a good chance to test
whether theory predicts results.

I guess you will find similar results, however, depending on how tight
the wheel is, will affect the change in the upper spoke at place being
pushed. In any event, it has more than double the effect of squeezing
pairs of spokes. The amount is difficult to assess because the
tensiometer occupies the place on the spoke where one would grasp a
spoke pair.

Jobst Brandt

Quoted message said:

Ben C said:

On 2006-11-12, [email hidden] <[email hidden]> wrote:
[snip]

Quoted message said:

I just looked and found that Mavic re-did their wretched website in
mid-October. You still can't search it, but it looks as if there's less
to rummage through. Mavic may have tossed out some stuff when they
re-did their web-site.

Like you, I couldn't find the pdf, either, but what Jim Beam wrote
sounded familiar, and I see that he's posted a saved copy.

Their website is certainly wretched, but the pdf is there, it's called
"SpokeTension.pdf", and I think it's under the "Rims" heading rather
than the "Wheels" heading.

Dear Ben,

You're right--the wood block pdf is still on the Mavic site.

Peter and I didn't find it because the site is such a hideously
unorganized mess.

[snip]

Quoted message said:

Apparently, this technique is now considered pre-2007, since it
doesn't appear in the mammoth "Complete 2007 technical manual" pdf or
in the "rims" or "wheels" section at the opening of the newly
mis-designed site.

The 2007 WheelBuilding.pdf and WheelBuildingContinued.pdf seem to be
explanations of how to assemble "boutique" wheels with very few spokes
and/or radial lacings on the front wheel. They did say somewhere that
the 2007 manuals covered things that hadn't been covered in previous
manuals.

Interestingly the spoke tension required for these wheels with very few
spokes doesn't seem to be all that high.

Quoted message said:

One theory is that Mavic requires a login and password to keep the
public out of its web site, lest we become frustrated.

One thing that is quite useful is that you can get the dimensions of
individual rims for checking spoke lengths without relying on the rims
being in the database of the spoke length calculator you're using.

And the wood block technique doesn't sound like a bad idea to me. I
tried it on a wheel I've been practising on, and it brought out lots of
cracking sounds that I hadn't uncovered by squeezing spoke pairs,
implying that it was doing a good job of relieving or seating something.

Ozark Bicycle said:

Ben C wrote:

[snip]

Quoted message said:

Quoted message said:

So does linseed oil actually lock the threads?

When wet, it lubes the spoke threads. When it dries, it provides a
gentle thread lock.

Thanks everyone, I did actually find some of the stuff, so I'll give it
a go.

Ben C said:

Quoted message said:

Ben C said:

On 2006-11-12, [email hidden] <[email hidden]> wrote:
[snip]
> I just looked and found that Mavic re-did their wretched website in
> mid-October. You still can't search it, but it looks as if there's less
> to rummage through. Mavic may have tossed out some stuff when they
> re-did their web-site.
>
> Like you, I couldn't find the pdf, either, but what Jim Beam wrote
> sounded familiar, and I see that he's posted a saved copy.

Their website is certainly wretched, but the pdf is there, it's called
"SpokeTension.pdf", and I think it's under the "Rims" heading rather
than the "Wheels" heading.

Dear Ben,

You're right--the wood block pdf is still on the Mavic site.

Peter and I didn't find it because the site is such a hideously
unorganized mess.

[snip]

Quoted message said:

Apparently, this technique is now considered pre-2007, since it
doesn't appear in the mammoth "Complete 2007 technical manual" pdf or
in the "rims" or "wheels" section at the opening of the newly
mis-designed site.

The 2007 WheelBuilding.pdf and WheelBuildingContinued.pdf seem to be
explanations of how to assemble "boutique" wheels with very few spokes
and/or radial lacings on the front wheel. They did say somewhere that
the 2007 manuals covered things that hadn't been covered in previous
manuals.

Interestingly the spoke tension required for these wheels with very few
spokes doesn't seem to be all that high.

Quoted message said:

One theory is that Mavic requires a login and password to keep the
public out of its web site, lest we become frustrated.

One thing that is quite useful is that you can get the dimensions of
individual rims for checking spoke lengths without relying on the rims
being in the database of the spoke length calculator you're using.

And the wood block technique doesn't sound like a bad idea to me. I
tried it on a wheel I've been practising on, and it brought out lots of
cracking sounds that I hadn't uncovered by squeezing spoke pairs,
implying that it was doing a good job of relieving or seating something.

Dear Ben,

I haven't tried the wood block technique yet. I've drilled some holes
in a metal bar to make a rig, but I need to pick up some lag bolts to
anchor things.

Jobst and Joe Riel have offered some further comments.

I did take the front wheel off the Fury RoadMaster, which had about a
thousand miles on it and whose spokes had been squeezed in a hopeful
fashion.

When I leaned on the horizontal rim, I got the same cracking noises
that you noticed, which makes me wonder if tension might be raised
higher or reduced lower than by squeezing spokes pairs. I couldn't
tell which spokes were making the cracking noises, which soon stopped,
consistent with a spoke and nipple unwinding.

I'm about 190~195 lbs. When I leaned on a bathroom scale on a counter,
it showed about 100 lbs. I'm really curious to see what happens to
spoke tension when I load the sides of the horizontal rim.

Cheers,

Carl Fogel

Quoted message said:

Bill Platt said:

Quoted message said:

How do you "cant and drill" a hole in the hub
flange so that both inbound *and* outbound spokes are "optimized?"
If the hole was so canted, would that mean that the hubs should not
be deformed during the build?

Quoted message said:

I think with the exception of weird special purpose hubs, all the
holes are the same. There is no cant. The spoke is bent into a J
to take care of that. The holes are all drilled parallel to the hub
axis. The edges of the holes are chamfered, but as noted upthread,
the spokes seat into the hub and create additional indentations.

Many hubs have slightly cup shaped flanges that approximate the angle
of the average spoke to the rim so that outbound spokes do not have so
hard a time of aligning to the angle. These flanges are drilled, one
hole at a time by an NC machine that indexes at the appropriate
interval as the angled drill penetrates the flange normal to its
surface.

No matter which method was used to make the holes, I haven't figured out
how to cant the holes of the hub "optimally" for all of the variations
of outbound/inbound and crossing patterns. I hope jim beam can clarify.

--
Dave
dvt at psu dot edu

Everyone confesses that exertion which brings out all the powers of body
and mind is the best thing for us; but most people do all they can to
get rid of it, and as a general rule nobody does much more than
circumstances drive them to do. -Harriet Beecher Stowe, abolitionist and
novelist (1811-1896)

Sheldon Brown said:

Ben C said:

Quoted message said:

So does linseed oil actually lock the threads?
I thought it was just to
lubricate them a bit and provide a corrosion barrier.

Ozark Bicycle replied:

Quoted message said:

When wet, it lubes the spoke threads. When it dries, it provides a
gentle thread lock.

Yep, this is a traditional technique, works very well...if you can
stand the smel!

Personally, I can't.

Sheldon "Yeccccch" Brown

Presumably, teflon lube, is not such a good idea.

Its all I had at the time.

--
Andy Morris

AndyAtJinkasDotFreeserve.Co.UK

Love this:
Put an end to Outlook Express's messy quotes
http://home.in.tum.de/~jain/software/oe-quotefix/

--
Posted via NewsDemon.com - Premium Uncensored Newsgroup Service
------->>>>>>http://www.NewsDemon.com<<<<<<------
Unlimited Access, Anonymous Accounts, Uncensored Broadband Access

Andy Morris said:

Quoted message said:

Quoted message said:

> So does linseed oil actually lock the threads? I thought it was
> just to lubricate them a bit and provide a corrosion barrier.

Quoted message said:

Quoted message said:

Quoted message said:

When wet, it lubes the spoke threads. When it dries, it provides
a gentle thread lock.

Linseed oil doesn't "dry" by evaporation but rather polymerizes and
becomes a stiff tar. Vegetable oils of various kinds (olive oil) do
that in the kitchen while oxidizing and becoming rancid.

Quoted message said:

Quoted message said:

Yep, this is a traditional technique, works very well...if you can
stand the smell!

Quoted message said:

Quoted message said:

Personally, I can't.

Quoted message said:

Presumably, Teflon lube, is not such a good idea.

Quoted message said:

Its all I had at the time.

Why would Teflon lube be a bad idea. Maybe you don't understand what
all this thread locking stuff is about. Unless spokes repeatedly
become slack in use, spoke nipples cannot unscrew. This whole concept
arose wit machine built wheels that could not be made adequately
tight. Therefore, since low tension spokes become slack frequently
when in use, especially with a heavy rider or on rough roads, such
wheels came out of true.

Wheelsmith had one of the first Holland Mechanics wheel building
stations in the USA and developed SpokePrep to cover for loosely
spoked wheels that they produced. With the fad of wheels with few
spokes in full swing, even more wheels that formerly are at risk of
loosening spokes in normal use.

Ten spokes! Quick, where's the Loctite!

Jobst Brandt

Andy Morris said:

Quoted message said:

Quoted message said:

> So does linseed oil actually lock the threads? I thought it was
> just to lubricate them a bit and provide a corrosion barrier.

Quoted message said:

Quoted message said:

Quoted message said:

When wet, it lubes the spoke threads. When it dries, it provides
a gentle thread lock.

Linseed oil doesn't "dry" by evaporation but rather by polymerizing
and becoming a stiff tar. Vegetable oils of various kinds (olive oil)
do that in the kitchen while oxidizing and becoming rancid.

Quoted message said:

Quoted message said:

Yep, this is a traditional technique, works very well...if you can
stand the smell!

Quoted message said:

Quoted message said:

Personally, I can't.

Quoted message said:

Presumably, Teflon lube, is not such a good idea.

Quoted message said:

Its all I had at the time.

Why would Teflon lube be a bad idea. Maybe you don't understand what
all this thread locking stuff is about. Unless spokes repeatedly
become slack in use, spoke nipples cannot unscrew. This whole concept
arose with machine built wheels that could not be made adequately
tight. That of course is a subject all for itself (a thread that can
be found on the web). Therefore, since wheels with low tension spokes
that become slack frequently in use, especially with a heavy rider or
on rough roads, they became untrue.

Wheelsmith had one of the first Holland Mechanics wheel building
stations in the USA and developed SpokePrep to cover for loosely
spoked wheels they produced. With the fad of wheels with few spokes
in full swing, even more wheels than formerly are subject to loosening
spokes in normal use.

Ten spokes! Quick, where's the Loctite!

Jobst Brandt

Quoted message said:

Andy Morris said:

Quoted message said:

>> So does linseed oil actually lock the threads? I thought it was
>> just to lubricate them a bit and provide a corrosion barrier.

Quoted message said:

Quoted message said:

> When wet, it lubes the spoke threads. When it dries, it provides
> a gentle thread lock.

Linseed oil doesn't "dry" by evaporation but rather polymerizes and
becomes a stiff tar.

Geez, who cares? The end result is the same: a gentle threadlock

Quoted message said:

Vegetable oils of various kinds (olive oil) do
that in the kitchen while oxidizing and becoming rancid.

I'll keep that in mind the next time I have the urge to use linseed oil
in my balsamic vinegrette!

Or olive oil on my spoke threads.....

Quoted message said:

Quoted message said:

Quoted message said:

Yep, this is a traditional technique, works very well...if you can
stand the smell!

Quoted message said:

Quoted message said:

Personally, I can't.

Quoted message said:

Presumably, Teflon lube, is not such a good idea.

Quoted message said:

Its all I had at the time.

Why would Teflon lube be a bad idea. Maybe you don't understand what
all this thread locking stuff is about. Unless spokes repeatedly
become slack in use, spoke nipples cannot unscrew. This whole concept
arose wit machine built wheels that could not be made adequately
tight.

Actually, Jobst, I believe the use of linseed oil as a threadlock on
handbuilt wheels predates all this. I would love to see solid evidence
to the contrary. Or even solid evidence of the widespread use of
linseed oil on machine built wheels. Can you provide such solid
evidence for either case?

On 2006-11-17, [email hidden] <[email hidden]> wrote:
[snip]

Quoted message said:

Why would Teflon lube be a bad idea. Maybe you don't understand what
all this thread locking stuff is about. Unless spokes repeatedly
become slack in use, spoke nipples cannot unscrew. This whole concept
arose with machine built wheels that could not be made adequately
tight. That of course is a subject all for itself (a thread that can
be found on the web). Therefore, since wheels with low tension spokes
that become slack frequently in use, especially with a heavy rider or
on rough roads, they became untrue.

Wheelsmith had one of the first Holland Mechanics wheel building
stations in the USA and developed SpokePrep to cover for loosely
spoked wheels they produced. With the fad of wheels with few spokes
in full swing, even more wheels than formerly are subject to loosening
spokes in normal use.

Is this because wheels with few spokes are built with a lower spoke
tension (for some reason) or is it because the rim is supported at fewer
points, and therefore the spokes share the load less, meaning each
individual spoke is dentensioned more as it passes through the contact
patch?

Sheldon's site, and common sense, say the tension should be as high as
you can get it without things cracking or threads stripping etc. at
wheel-building time.

But rim manufacturers don't recommend such high tensions from what I can
see. I tried searching the r.b.t. archives and found some discussion of
the possibility of increased corrosion leading to cracking around the
eyelets if the tension is high.

A common failure of rims is cracking around the eyelets. I had this on
my own rear rim. On the one hand insufficient tension could explain
this, because if the bottom spoke goes completely slack, the top spoke
will actually be pulled out through the eyelet. Another explanation is
that slacker spokes will deflect more as they detension, meaning more
movement and therefore wear around the eyelet. On the other hand, if the
rate of wear is not affected by tension, you might expect the actual
failure to occur sooner with a higher tension, as the point at which the
rim can no longer support the spoke tension will come sooner.

Do people usually see cracked eyelets on the drive side or on the
non-drive side of rear wheels? Maybe this would be an indicator of
whether high tension or low tension wears the rim more at the eyelets.

Ben C? said:

Quoted message said:

Why would Teflon lube be a bad idea. Maybe you don't understand
what all this thread locking stuff is about. Unless spokes
repeatedly become slack in use, spoke nipples cannot unscrew. This
whole concept arose with machine built wheels that could not be
made adequately tight. That of course is a subject all for itself
(a thread that can be found on the web). Therefore, since wheels
with low tension spokes that become slack frequently in use,
especially with a heavy rider or on rough roads, they became
untrue.

Quoted message said:

Quoted message said:

Wheelsmith had one of the first Holland Mechanics wheel building
stations in the USA and developed SpokePrep to cover for loosely
spoked wheels they produced. With the fad of wheels with few
spokes in full swing, even more wheels than formerly are subject to
loosening spokes in normal use.

Quoted message said:

Is this because wheels with few spokes are built with a lower spoke
tension (for some reason) or is it because the rim is supported at
fewer points, and therefore the spokes share the load less, meaning
each individual spoke is dentensioned more as it passes through the
contact patch?

Spoke tension with fewer spokes must be higher than for a 36 spokes,
for instance, because only one or two spokes are supporting the load.
Check out the thread of "the wheel stands on the bottom spokes".

Quoted message said:

Sheldon's site, and common sense, say the tension should be as high
as you can get it without things cracking or threads stripping
etc. at wheel-building time.

Quoted message said:

But rim manufacturers don't recommend such high tensions from what I
can see. I tried searching the r.b.t. archives and found some
discussion of the possibility of increased corrosion leading to
cracking around the eyelets if the tension is high.

Quoted message said:

A common failure of rims is cracking around the eyelets. I had this
on my own rear rim. On the one hand insufficient tension could
explain this, because if the bottom spoke goes completely slack, the
top spoke will actually be pulled out through the eyelet.

That occurs because rims are no longer built with sockets that
distribute spoke loads to inner and outer beds of the rim. Spoke
loads are concentrated on an eyelet whose diameter is little more than
a spoke nipple while sockets are more than 10mm in diameter at the
mouth and bear on both rim beds.

Quoted message said:

Another explanation is that slacker spokes will deflect more as they
detension, meaning more movement and therefore wear around the
eyelet. On the other hand, if the rate of wear is not affected by
tension, you might expect the actual failure to occur sooner with a
higher tension, as the point at which the rim can no longer support
the spoke tension will come sooner.

Spokes either bear the load by losing tension, or go slack and allow
spoke nipples to unscrew for which glue has become popular.

Quoted message said:

Do people usually see cracked eyelets on the drive side or on the
non-drive side of rear wheels? Maybe this would be an indicator of
whether high tension or low tension wears the rim more at the
eyelets.

They see them on both sides and front wheels. The deep cross section
aero rims avoid that because the load hangs in the bottom of the "V"
on a relatively thick aluminum bed.

Jobst Brandt

Quoted message said:

Ben C? writes:

[snip]

Quoted message said:

Quoted message said:

A common failure of rims is cracking around the eyelets. I had this
on my own rear rim. On the one hand insufficient tension could
explain this, because if the bottom spoke goes completely slack, the
top spoke will actually be pulled out through the eyelet.

That occurs because rims are no longer built with sockets that
distribute spoke loads to inner and outer beds of the rim. Spoke
loads are concentrated on an eyelet whose diameter is little more than
a spoke nipple while sockets are more than 10mm in diameter at the
mouth and bear on both rim beds.

Now you mention it I think I dimly remember those sockets from some
Mavic rims I had about 15 years ago.

Quoted message said:

Quoted message said:

Another explanation is that slacker spokes will deflect more as they
detension, meaning more movement and therefore wear around the
eyelet. On the other hand, if the rate of wear is not affected by
tension, you might expect the actual failure to occur sooner with a
higher tension, as the point at which the rim can no longer support
the spoke tension will come sooner.

Spokes either bear the load by losing tension, or go slack and allow
spoke nipples to unscrew for which glue has become popular.

I just meant the pre-tension. A spoke might be pulling on the eyelet
with a force of 900N (the wheel is in the truing stand for the sake of
argument, or floating around in an orbiting spacecraft, it doesn't
matter). The rim can withstand 900N and so doesn't crack. But over time
as the rim wears, it reaches a point where it can only withstand 890N,
so it cracks. But if the spoke had only been at 850N tension all along,
perhaps the rim would last a bit longer, assuming the rate of wear at
850N and 900N were about the same, which may be a false assumption. This
might be a reason for building wheels tight enough but not too tight.

Quoted message said:

Ben C? said:

Quoted message said:

Why would Teflon lube be a bad idea. Maybe you don't understand
what all this thread locking stuff is about. Unless spokes
repeatedly become slack in use, spoke nipples cannot unscrew. This
whole concept arose with machine built wheels that could not be
made adequately tight. That of course is a subject all for itself
(a thread that can be found on the web). Therefore, since wheels
with low tension spokes that become slack frequently in use,
especially with a heavy rider or on rough roads, they became
untrue.

Quoted message said:

Quoted message said:

Wheelsmith had one of the first Holland Mechanics wheel building
stations in the USA and developed SpokePrep to cover for loosely
spoked wheels they produced. With the fad of wheels with few
spokes in full swing, even more wheels than formerly are subject to
loosening spokes in normal use.

Quoted message said:

Is this because wheels with few spokes are built with a lower spoke
tension (for some reason) or is it because the rim is supported at
fewer points, and therefore the spokes share the load less, meaning
each individual spoke is dentensioned more as it passes through the
contact patch?

Spoke tension with fewer spokes must be higher than for a 36 spokes,

rubbish. check with mavic, velocity, alex, any of the rim manufacturers
- tension specs are the same regardless of drilling count. spoke
tension is determined by the fatigue properties of the rim. once spoke
tension is sufficient to not let spokes go slack, increasing spoke
tension above that level does NOT increase the strength of the wheel.
all it does is "borrow" bending "strength" from the rim to give
compressive "strength" to the spokes - a pointless exercise for
structural purposes, and one that raises loading in the rim closer to
both of its taco and cracking limits.

Quoted message said:

for instance, because only one or two spokes are supporting the load.
Check out the thread of "the wheel stands on the bottom spokes".

red herring.

Quoted message said:

Quoted message said:

Sheldon's site, and common sense, say the tension should be as high
as you can get it without things cracking or threads stripping
etc. at wheel-building time.

Quoted message said:

But rim manufacturers don't recommend such high tensions from what I
can see. I tried searching the r.b.t. archives and found some
discussion of the possibility of increased corrosion leading to
cracking around the eyelets if the tension is high.

Quoted message said:

A common failure of rims is cracking around the eyelets. I had this
on my own rear rim. On the one hand insufficient tension could
explain this, because if the bottom spoke goes completely slack, the
top spoke will actually be pulled out through the eyelet.

That occurs because rims are no longer built with sockets that
distribute spoke loads to inner and outer beds of the rim.

untrue.

Quoted message said:

Spoke
loads are concentrated on an eyelet whose diameter is little more than
a spoke nipple while sockets are more than 10mm in diameter at the
mouth and bear on both rim beds.

distorted rubbish. do the math.

Quoted message said:

Quoted message said:

Another explanation is that slacker spokes will deflect more as they
detension, meaning more movement and therefore wear around the
eyelet. On the other hand, if the rate of wear is not affected by
tension, you might expect the actual failure to occur sooner with a
higher tension, as the point at which the rim can no longer support
the spoke tension will come sooner.

Spokes either bear the load by losing tension,

so what happens to rims? according to jobstian theory, this wheel
should collapse:
http://home.comcast.net/~carlfogel/download/205lbs.jpeg
but it doesn't. why? because the rim is part of the load support
equation, something you /always/ ignore!

Quoted message said:

or go slack and allow
spoke nipples to unscrew for which glue has become popular.

so what? it works, and works well. and more moderate tension prevents
rims from cracking.

Quoted message said:

Quoted message said:

Do people usually see cracked eyelets on the drive side or on the
non-drive side of rear wheels? Maybe this would be an indicator of
whether high tension or low tension wears the rim more at the
eyelets.

They see them on both sides and front wheels.

on rims with excessive tension, yes. on rims with more moderated
tension, the only time they're seen, [if at all] is on the drive side
rear - where tension increases due to the low bracing angle are
significant. you know that tension increase is a function of 1/sin
theta, right?

Quoted message said:

The deep cross section
aero rims avoid that because the load hangs in the bottom of the "V"
on a relatively thick aluminum bed.

the only benefit of the deep section is rim stiffness - the stiffer the
rim, the less the load cycle magnitude on rim /and/ spoke. other than
that, a thick bed on /any/ rim helps mitigate cracking.

Ben C said:

Quoted message said:

Ben C? writes:

[snip]

Quoted message said:

Quoted message said:

A common failure of rims is cracking around the eyelets. I had this
on my own rear rim. On the one hand insufficient tension could
explain this, because if the bottom spoke goes completely slack, the
top spoke will actually be pulled out through the eyelet.

That occurs because rims are no longer built with sockets that
distribute spoke loads to inner and outer beds of the rim. Spoke
loads are concentrated on an eyelet whose diameter is little more than
a spoke nipple while sockets are more than 10mm in diameter at the
mouth and bear on both rim beds.

Now you mention it I think I dimly remember those sockets from some
Mavic rims I had about 15 years ago.

Quoted message said:

Quoted message said:

Another explanation is that slacker spokes will deflect more as they
detension, meaning more movement and therefore wear around the
eyelet. On the other hand, if the rate of wear is not affected by
tension, you might expect the actual failure to occur sooner with a
higher tension, as the point at which the rim can no longer support
the spoke tension will come sooner.

Spokes either bear the load by losing tension, or go slack and allow
spoke nipples to unscrew for which glue has become popular.

I just meant the pre-tension. A spoke might be pulling on the eyelet
with a force of 900N (the wheel is in the truing stand for the sake of
argument, or floating around in an orbiting spacecraft, it doesn't
matter). The rim can withstand 900N and so doesn't crack. But over time
as the rim wears, it reaches a point where it can only withstand 890N,
so it cracks.

can't say that. the rim doesn't wear in the section that has the point
contact load, so you're not going to see yield decrease over time.
fatigue properties depend on how far along the s-n graph you are.

Quoted message said:

But if the spoke had only been at 850N tension all along,
perhaps the rim would last a bit longer,

perhaps, but...

Quoted message said:

assuming the rate of wear at
850N and 900N were about the same,

not as a function of wear!

Quoted message said:

which may be a false assumption.

indeed, if you base it on wear. fatigue life is another matter, and may
indeed be mitigated by lower tension.

Quoted message said:

This
might be a reason for building wheels tight enough but not too tight.

build to rim manufacturer spec. no less, no more. if, as can sometimes
be the case with todays highly dished wheels, non-drive side spoke
nipples get slack enough to unscrew, use thread lock. that's why it's sold.

Thank you both for responding, some more questions:

jim beam said:

Quoted message said:

Ben C? writes:

[snip]

Quoted message said:

Quoted message said:

Quoted message said:

> Wheelsmith had one of the first Holland Mechanics wheel building
> stations in the USA and developed SpokePrep to cover for loosely
> spoked wheels they produced. With the fad of wheels with few
> spokes in full swing, even more wheels than formerly are subject to
> loosening spokes in normal use.

Quoted message said:

Is this because wheels with few spokes are built with a lower spoke
tension (for some reason) or is it because the rim is supported at
fewer points, and therefore the spokes share the load less, meaning
each individual spoke is dentensioned more as it passes through the
contact patch?

Spoke tension with fewer spokes must be higher than for a 36 spokes,

rubbish. check with mavic, velocity, alex, any of the rim manufacturers
- tension specs are the same regardless of drilling count. spoke
tension is determined by the fatigue properties of the rim. once spoke
tension is sufficient to not let spokes go slack, increasing spoke
tension above that level does NOT increase the strength of the wheel.
all it does is "borrow" bending "strength" from the rim to give
compressive "strength" to the spokes - a pointless exercise for
structural purposes, and one that raises loading in the rim closer to
both of its taco and cracking limits.

Mavic say this:

"
Screw the nut of the socket and increase the tension of the spokes after
putting one or two drops of Mavic thread lock on the socket thread

(Crossmax UST and Ksyrium SSC only) :
- 70 - 90 kg for a front Crossride or Cosmos wheel.
- 110 - 130 kg for a front Cosmic Carbone SSC wheel.
- Ksyrium SSC : 90 - 110 kg for the front wheel and 130 - 150 kg for the
rear wheel on the free wheel side.
- Crossmax UST : 100 - 120 kg for the front wheel and 130 - 150 kg for
the rear wheel on the free wheel side.
"

Most or all of these wheels have less than 32 spokes.

[snip]

Quoted message said:

Quoted message said:

or go slack and allow
spoke nipples to unscrew for which glue has become popular.

so what? it works, and works well. and more moderate tension prevents
rims from cracking.

Are there any other harmful sideeffects of spokes going completely slack
besides just the nipples unscrewing?

For example, these are the things I'm concerned about:

1. increased fatigue around the nipple because of higher deflection.
2. the top spokes increasing in tension beyond the original pretension
because the load exceeds the pretension of the bottom spokes (they go
completely slack).
3. increased fatigue of the spokes themselves, perhaps around the elbow,
because they are actually being bent slightly in compression, leading
them to break.

Quoted message said:

Quoted message said:

Quoted message said:

Do people usually see cracked eyelets on the drive side or on the
non-drive side of rear wheels? Maybe this would be an indicator of
whether high tension or low tension wears the rim more at the
eyelets.

They see them on both sides and front wheels.

on rims with excessive tension, yes. on rims with more moderated
tension, the only time they're seen, [if at all] is on the drive side
rear - where tension increases due to the low bracing angle are
significant. you know that tension increase is a function of 1/sin
theta, right?

So are you saying excessive tension does actually promote cracking
around the eyelets in use (as opposed to the cracks appearing in the
truing stand before the wheel's even been put on the bike) , and if so
is there any explanation for how that works (I did read something about
"stress corrosion" in the archives).

http://tinyurl.com/u753r

jim beam said:

Ben C said:

Quoted message said:

Ben C? writes:

[snip]

Quoted message said:

Quoted message said:

I just meant the pre-tension. A spoke might be pulling on the eyelet
with a force of 900N (the wheel is in the truing stand for the sake of
argument, or floating around in an orbiting spacecraft, it doesn't
matter). The rim can withstand 900N and so doesn't crack. But over time
as the rim wears, it reaches a point where it can only withstand 890N,
so it cracks.

can't say that. the rim doesn't wear in the section that has the point
contact load, so you're not going to see yield decrease over time.
fatigue properties depend on how far along the s-n graph you are.

Quoted message said:

But if the spoke had only been at 850N tension all along,
perhaps the rim would last a bit longer,

perhaps, but...

Quoted message said:

assuming the rate of wear at
850N and 900N were about the same,

not as a function of wear!

Quoted message said:

which may be a false assumption.

indeed, if you base it on wear. fatigue life is another matter, and may
indeed be mitigated by lower tension.

I was using the word "wear" in a general sense, not being an engineer. I
suppose wear is strictly what you get when things rub together in some
way, i.e. what happens on a rim where the brake blocks touch it? And
fatigue is the process by which if you bend a teaspoon backwards and
forwards a few times it breaks.

Quoted message said:

Quoted message said:

This might be a reason for building wheels tight enough but not too
tight.

Quoted message said:

build to rim manufacturer spec. no less, no more.

This sounds like the best advice. But it's interesting to know what the
reasons are.

Ben C said:

Thank you both for responding, some more questions:

jim beam said:

Quoted message said:

Ben C? writes:

[snip]

Quoted message said:

Quoted message said:

>> Wheelsmith had one of the first Holland Mechanics wheel building
>> stations in the USA and developed SpokePrep to cover for loosely
>> spoked wheels they produced. With the fad of wheels with few
>> spokes in full swing, even more wheels than formerly are subject to
>> loosening spokes in normal use.
> Is this because wheels with few spokes are built with a lower spoke
> tension (for some reason) or is it because the rim is supported at
> fewer points, and therefore the spokes share the load less, meaning
> each individual spoke is dentensioned more as it passes through the
> contact patch?
Spoke tension with fewer spokes must be higher than for a 36 spokes,

rubbish. check with mavic, velocity, alex, any of the rim manufacturers
- tension specs are the same regardless of drilling count. spoke
tension is determined by the fatigue properties of the rim. once spoke
tension is sufficient to not let spokes go slack, increasing spoke
tension above that level does NOT increase the strength of the wheel.
all it does is "borrow" bending "strength" from the rim to give
compressive "strength" to the spokes - a pointless exercise for
structural purposes, and one that raises loading in the rim closer to
both of its taco and cracking limits.

Mavic say this:

"
Screw the nut of the socket and increase the tension of the spokes after
putting one or two drops of Mavic thread lock on the socket thread

(Crossmax UST and Ksyrium SSC only) :
- 70 - 90 kg for a front Crossride or Cosmos wheel.
- 110 - 130 kg for a front Cosmic Carbone SSC wheel.
- Ksyrium SSC : 90 - 110 kg for the front wheel and 130 - 150 kg for the
rear wheel on the free wheel side.
- Crossmax UST : 100 - 120 kg for the front wheel and 130 - 150 kg for
the rear wheel on the free wheel side.
"

Most or all of these wheels have less than 32 spokes.

indeed. all those tensions are in the same ballpark as those quoted for
32 or 36 spoke standard rims. the cosmos at 90kg has only 24 spokes -
presumably a function of the lesser grade 6061 alloy than their other
rim alloy, "maxtal", [whatever that is] that's used in the ksyrium series.

Quoted message said:

[snip]

Quoted message said:

Quoted message said:

or go slack and allow
spoke nipples to unscrew for which glue has become popular.

so what? it works, and works well. and more moderate tension prevents
rims from cracking.

Are there any other harmful sideeffects of spokes going completely slack
besides just the nipples unscrewing?

For example, these are the things I'm concerned about:

1. increased fatigue around the nipple because of higher deflection.

rare.

Quoted message said:

2. the top spokes increasing in tension beyond the original pretension
because the load exceeds the pretension of the bottom spokes (they go
completely slack).

spoke tension increases slightly, but truth is, the rim is flexible and
the load is distributed among all the spokes, so the combined effect is
that tension doesn't increase specifically at the top and won't kill
spokes on its own. spoke tension increases much more under lateral
loads like when you honk up a hill.

Quoted message said:

3. increased fatigue of the spokes themselves, perhaps around the elbow,
because they are actually being bent slightly in compression, leading
them to break.

they don't compress - this is wire, it bends first. but you /do/ get a
lot more flexing, and that does indeed fatigue spoke elbows.

Quoted message said:

Quoted message said:

Quoted message said:

> Do people usually see cracked eyelets on the drive side or on the
> non-drive side of rear wheels? Maybe this would be an indicator of
> whether high tension or low tension wears the rim more at the
> eyelets.
They see them on both sides and front wheels.

on rims with excessive tension, yes. on rims with more moderated
tension, the only time they're seen, [if at all] is on the drive side
rear - where tension increases due to the low bracing angle are
significant. you know that tension increase is a function of 1/sin
theta, right?

So are you saying excessive tension does actually promote cracking
around the eyelets in use (as opposed to the cracks appearing in the
truing stand before the wheel's even been put on the bike)

yes. you're raising the mean load, then cycling stress from there.
that increases fatigue considerably.

Quoted message said:

, and if so
is there any explanation for how that works (I did read something about
"stress corrosion" in the archives).

http://tinyurl.com/u753r

stress corrosion may indeed be a factor because the rim cracking
commonly seen typically follows extrusion lines well away from the
loading zone.

jim beam said:

Ben C wrote:

[snip]

Quoted message said:

Quoted message said:

3. increased fatigue of the spokes themselves, perhaps around the elbow,
because they are actually being bent slightly in compression, leading
them to break.

they don't compress - this is wire, it bends first. but you /do/ get a
lot more flexing, and that does indeed fatigue spoke elbows.

[snip]

Quoted message said:

Quoted message said:

So are you saying excessive tension does actually promote cracking
around the eyelets in use (as opposed to the cracks appearing in the
truing stand before the wheel's even been put on the bike)

yes. you're raising the mean load, then cycling stress from there.
that increases fatigue considerably.

I think this answers the question I just asked in my previous post.

So to sum up, if spokes are breaking at the elbows it probably means
they're too loose; but if rims are cracking around the spoke holes,
they're probably too tight.

I'm guessing that the axial stress cycle caused by riding on a
sufficiently tensioned steel spoke (i.e. one that never goes slack)
would take a very large number of cycles before it caused a fatigue
failure and so would be unlikely to occur before one of the other
kinds of failure.