wheelbuilding question

jabpn said:

I have recently begun the forray into wheel-building. I have read a
lot of subject matter that states, for rear wheels, that the
non-freewheel side of the wheel will not be as highly tensioned as the
freewheel side. With disc brakes becoming more and more popular, does
this still hold true?

Yes, for bikes with derailer gearing.

Quoted message said:

It seems to make sense that the rotor side
should have more tension now to provide proper wheel support. Any
info you can send me regarding your experience or knowledge would be
so helpful. All wheel-building websites and books I've found/read
just aren't updated enough to answer the questions about new
technologies in the bicycling industry.

That's 'cause there's nothing new to update. You'll only have one disc
rotor, which won't take up nearly as much lateral space as a cassette

Sheldon "No News Is Good News" Brown

(sorry, don't have my quotes collection on this $#!@*! Wintel box.)

Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com
Useful articles about bicyces and cycling
http://sheldonbrown.com

In article <[email hidden]>,

jabpn said:

I have read a
lot of subject matter that states, for rear wheels, that the
non-freewheel side of the wheel will not be as highly tensioned as the
freewheel side. With disc brakes becoming more and more popular, does
this still hold true?

Spoke tension is a vector and the left/right components of the spokes
on both sides must add to 0 for the rim to remain stationary.

Where the spokes on one side are more angled than the other their tension
has a larger left/right component so the total tension must be lower on
that side.

Total tension on the two sides won't be equal unless the spokes approach
the rim at the same angle. While a disc wheel can have less difference
it's not going to be symetrical.
--
<a href="http://www.poohsticks.org/drew/">Home Page</a>
Life is a terminal sexually transmitted disease.

jabpn said:

I have recently begun the forray into wheel-building. I have read a
lot of subject matter that states, for rear wheels, that the
non-freewheel side of the wheel will not be as highly tensioned as the
freewheel side. With disc brakes becoming more and more popular, does
this still hold true?

yes.

Quoted message said:

It seems to make sense that the rotor side
should have more tension now to provide proper wheel support. Any
info you can send me regarding your experience or knowledge would be
so helpful.

the relative tensions are a function of the angles the spokes make with
the rim, which is in turn determined by flange spacing. if the flange
spacing on a disk hub is the same as a non-disk hub, the relative
tensions will be the same.

Quoted message said:

All wheel-building websites and books I've found/read
just aren't updated enough to answer the questions about new
technologies in the bicycling industry.

it's not new technology, but you're right, this is not covered in any
book i've seen. however, if you want to look at the math, it's in the
latest version of damon renard's spoke calculator spreadsheet.

[email hidden] (jabpn) wrote in message news:<[email hidden]>...

Quoted message said:

I have recently begun the forray into wheel-building. I have read a
lot of subject matter that states, for rear wheels, that the
non-freewheel side of the wheel will not be as highly tensioned as the
freewheel side. With disc brakes becoming more and more popular, does
this still hold true?

Yes. The rotor mounting stuff moves that flange inboard a bit, but
not as much as the cassette.

Quoted message said:

It seems to make sense that the rotor side
should have more tension now to provide proper wheel support. Any
info you can send me regarding your experience or knowledge would be
so helpful.

That's true - the more tension you can bring to bear (before
destroying the rim) the better. Read "The Bicycle Wheel" by Jobst
Brandt. Lots of good info on the "why" of wheelbuilding, and a nice
section of "how" as well. He does not specifically address disk
brakes, but from the info, you can determine how the spokes should be
to best support the loads.

"Zinn and the Art of Mountain Bike Maintenance" by Lenard Zinn has a
section on wheelbuilding that has a nice how-to that directly
addresses disk brake wheels.

Quoted message said:

All wheel-building websites and books I've found/read
just aren't updated enough to answer the questions about new
technologies in the bicycling industry.

The Zinn book is nice - it has other stuff that's useful, like an
appendix containing a decent torque table.

If you are interested in reading some long-winded drivel I have
written recently, find the thread in this group titled "Wheelbuilding
Question(s)". One of the things that shocked me was that for my rim
and hub choice, the difference between the length of the longest and
shortest spokes and was 1.3mm. IOW, one length to do all of the
spoking. Sort of counter-intuitive, but the front wheel built up just
fine, and I suspect that the rear will build up equally well.

Good luck, and tell us how things work out.
--
Jonesy

Jonesy said:

[email hidden] (jabpn) wrote in message news:<[email hidden]>...

Quoted message said:

I have recently begun the forray into wheel-building. I have read a
lot of subject matter that states, for rear wheels, that the
non-freewheel side of the wheel will not be as highly tensioned as the
freewheel side. With disc brakes becoming more and more popular, does
this still hold true?

Yes. The rotor mounting stuff moves that flange inboard a bit, but
not as much as the cassette.

Quoted message said:

It seems to make sense that the rotor side
should have more tension now to provide proper wheel support. Any
info you can send me regarding your experience or knowledge would be
so helpful.

That's true - the more tension you can bring to bear (before
destroying the rim) the better. Read "The Bicycle Wheel" by Jobst
Brandt.

i know that "high tension" recommendation is "in the book" and often
repeated here, but it's a fundamentally flawed piece of advice. the
closer a rim is operated to it's yield point, the less will be its
fatigue life, with the kind of results reported here yesterday:

http://mixednutsband.com/crack4.jpg

just because a rim doesn't fail with static load, doesn't mean it can
take the fatigue load. that's why there are so many reliability
complaints here on r.b.t.

in addition, as can be seen in damon rinard's experiments, increasing
spoke tension makes absolutely no difference to lateral strength. see:

http://www.sheldonbrown.com/rinard/wheel/tension.gif

original page:
http://www.sheldonbrown.com/rinard/wheel/index.htm

max spoke tension is determined by the rim's manufacturer. something
like a mavic open pro has a recommended max tension of 100-110 kgf.

Quoted message said:

Lots of good info on the "why" of wheelbuilding, and a nice
section of "how" as well. He does not specifically address disk
brakes, but from the info, you can determine how the spokes should be
to best support the loads.

"Zinn and the Art of Mountain Bike Maintenance" by Lenard Zinn has a
section on wheelbuilding that has a nice how-to that directly
addresses disk brake wheels.

Quoted message said:

All wheel-building websites and books I've found/read
just aren't updated enough to answer the questions about new
technologies in the bicycling industry.

The Zinn book is nice - it has other stuff that's useful, like an
appendix containing a decent torque table.

If you are interested in reading some long-winded drivel I have
written recently, find the thread in this group titled "Wheelbuilding
Question(s)". One of the things that shocked me was that for my rim
and hub choice, the difference between the length of the longest and
shortest spokes and was 1.3mm. IOW, one length to do all of the
spoking. Sort of counter-intuitive, but the front wheel built up just
fine, and I suspect that the rear will build up equally well.

Good luck, and tell us how things work out.

jab-<< that the
non-freewheel side of the wheel will not be as highly tensioned as the
freewheel side. With disc brakes becoming more and more popular, does
this still hold true? >><BR><BR>

Yes but with hub flange placement, the tension between left and right is closer
to the same.

Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"

[email hidden] (jabpn) wrote in message news:<[email hidden]>...

Thanks all for the advice. I'll let you know how it goes as soon as
my supplies come in and I can start. I'm actually replacing my Deore
Disc hub with an Deore XT 756 Disc hub. (figured I might as well
upgrade now rather than later. Although I'll probably stay with my
X223 Mavic rims instead of, say, Rhino Lites for now). I hate downtime
and can't wait to get back on the bike!!

On Fri, 09 Jul 2004 22:09:48 -0700, jim beam <[email hidden]>

Quoted message said:

in addition, as can be seen in damon rinard's experiments, increasing
spoke tension makes absolutely no difference to lateral strength. see:

http://www.sheldonbrown.com/rinard/wheel/tension.gif

original page:
http://www.sheldonbrown.com/rinard/wheel/index.htm

Careful; the info on that page may not have much to do with a wheel's
lateral strength. Here's a quote from that link:

"It must be emphasized that wheel stiffness is not wheel strength, and
in fact may be unrelated to it. I am measuring stiffness, not
strength."

Also, and this statement doesn't appear to be backed up with any
measurements on that page, but he also says (under question #1):

"A wheel whose spokes become slack while riding is a weak wheel,
because slack spokes cannot support the rim. This can be avoided to a
large extent by building wheels with tighter spokes."

However, I wonder if Jobst's "slight taco" method is only one
potential upper limit on spoke tension. Rims cracking in fatigue,
nipples rounding, hub flanges breaking, etc. may be some others.

But I think we agree in practice. Without lots of experimentation,
it's difficult for me to predict the fatigue stuff before I build the
wheel, so I generally follow the manufacturer's specifications when
available.

jim beam said:

in addition, as can be seen in damon rinard's experiments, increasing
spoke tension makes absolutely no difference to lateral strength. see:

http://www.sheldonbrown.com/rinard/wheel/tension.gif

original page:
http://www.sheldonbrown.com/rinard/wheel/index.htm

Rinard's wheel test did not test (lateral) strength, as he
stated in his first paragraph: "I am measuring stiffness,
not strength." His test of measuring lateral stiffness at
varying static spoke tension mainly serves to confirm
Hooke's Law.

However, if you take a closer look at the graph, you'll
notice that the deflection increases dramatically when he
backs the tension off below a certain threshold. This
increase in deflection shows a wheel that is more likely to
fail under load. Although Rinard is using a fixed load, it
can be inferred from this data that increased spoke tension
can increase the strength of a wheel. Indeed, you're
supposition that "increasing spoke tension makes absolutely
no difference in lateral strength" is directly contradicted
by Rinard's conclusion from his test. From the web page
referenced above:

"A wheel whose spokes become slack while riding is a weak
wheel, because slack spokes cannot support the rim. This can
be avoided to a large extent by building wheels with tighter
spokes. If spokes are tighter initially, then the sudden
increase in flexibility shown in data points 9 and 10 is
less likely to occur in use because a tighter wheel can bear
a higher load before spokes become slack."

Quoted message said:

max spoke tension is determined by the rim's manufacturer. something
like a mavic open pro has a recommended max tension of 100-110 kgf.

While one might like to think that rim manufacturers would
recommend maximum tensions for their rims, I have never
actually seen a manufacturer actually publish such data.
Where did you get the value for the Mavic Open Pro?

On the other hand, the concept of excess spoke tension is
often used as a dodge by manufacturers to avoid warranty
replacement for cracked rims. In none of the cases that I
have seen where a manufacturer's rep. denied a warranty by
claiming "the spoke tension must have been too high", no
measurement of actual spoke tension has been made to base
that claim on, nor has the rep. been able to state what the
recommended max. tension should be. The "excess tension"
argument has simply been used as an easy out.

Mark McMaster
[email hidden]

Mark McMaster said:

jim beam said:

in addition, as can be seen in damon rinard's experiments, increasing
spoke tension makes absolutely no difference to lateral strength. see:

http://www.sheldonbrown.com/rinard/wheel/tension.gif

original page:
http://www.sheldonbrown.com/rinard/wheel/index.htm

Rinard's wheel test did not test (lateral) strength, as he stated in his
first paragraph: "I am measuring stiffness, not strength." His test of
measuring lateral stiffness at varying static spoke tension mainly
serves to confirm Hooke's Law.

hookes law merely states that deformation is directly proportional to
load below yield - the definition of elastic deformation. it's no
predictor of yield or modulus, both of which are measures of "strength".
by that same argument, increasing tension does not increase strength
just the same as it does not increase stiffness.

Quoted message said:

However, if you take a closer look at the graph, you'll notice that the
deflection increases dramatically when he backs the tension off below a
certain threshold. This increase in deflection shows a wheel that is
more likely to fail under load.

that's an assumption, not a fact. the deflection increases, for slack
spokes /because/ they're slack. if you're towing a car with a slack
rope, the distance between the two cars will increase until the rope
becomes taught. then the distance between the two cars is essentially
fixed and subject only to minor stretching of the rope - many orders of
magnitude less that slack take-up.

Quoted message said:

Although Rinard is using a fixed load,
it can be inferred from this data that increased spoke tension can
increase the strength of a wheel.

"inferred" how? the material does not change - this material still has
to obey hookes law until it yields. increasing load merely makes it
bend further. if you think about it, pre-tension serves to reduce the
load capacity of a component not increase it.

Quoted message said:

Indeed, you're supposition that
"increasing spoke tension makes absolutely no difference in lateral
strength" is directly contradicted by Rinard's conclusion from his
test. From the web page referenced above:

"A wheel whose spokes become slack while riding is a weak wheel, because
slack spokes cannot support the rim. This can be avoided to a large
extent by building wheels with tighter spokes. If spokes are tighter
initially, then the sudden increase in flexibility shown in data points
9 and 10 is less likely to occur in use because a tighter wheel can bear
a higher load before spokes become slack."

there's no contradiction. the left part of the graph is essentially a
flat line. leftwards is increasing tension. once you're in the flat
line region, increasing tension is not increasing lateral stiffness.

Quoted message said:

Quoted message said:

max spoke tension is determined by the rim's manufacturer. something
like a mavic open pro has a recommended max tension of 100-110 kgf.

While one might like to think that rim manufacturers would recommend
maximum tensions for their rims, I have never actually seen a
manufacturer actually publish such data. Where did you get the value for
the Mavic Open Pro?

mavic's tech service department - i called them. you can also google
this group - peter chisholm can quote you tensions for a number of rims.

Quoted message said:

On the other hand, the concept of excess spoke tension is often used as
a dodge by manufacturers to avoid warranty replacement for cracked
rims.

i can see this might be a dodge sometimes, at least at the retail level,
but on a trade basis [the majority of the business] a manufacturer is
entitled to not be second-guessed by a consumer about use in service.
if an diving cylinder manufacturer specified a certain maximum charge
pressure, but a user chose to exceed that manufacturer's limit because
they wanted to extend their dive time, who would be liable for the
resulting cylinder failure? how about a retailer recommending excess
pressure to a consumer because they thought they knew better than the
manufacturer?

Quoted message said:

In none of the cases that I have seen where a manufacturer's rep.
denied a warranty by claiming "the spoke tension must have been too
high", no measurement of actual spoke tension has been made to base that
claim on,

how are you going to measure original tension once the rim has failed
and slackened the spokes? you /can/ research the s-n fatigue graph for
a component and map out cycles to failure for each load increment. once
you know stress and the curve, you can accurately predict cycles to
failure. likewise, if you can judge cycles to failure from braking
surface wear, you know very closely the load to which the rim has been
subject. and that can also be referenced back to the rim's batch number
and q.c. lab tests. if it's not from a defective batch, then the rim
/has/ to have been subect to use outside of spec.

Quoted message said:

nor has the rep. been able to state what the recommended max.
tension should be.

as stated above, mavic service dept had no problem telling me
recommended tensions.

Quoted message said:

The "excess tension" argument has simply been used
as an easy out.

this may be true, but it may not. how many times have you been in a
store and watched other people arguing over something petty like
returning a used garment? 9 times out of 10, the returnee with attitude
will be given a hard time, just because the store personnel hate being
treated like dirt, not because there isn't a valid argument.

"jim beam" <[email hidden]> wrote

Quoted message said:

Jonesy wrote:

Quoted message said:

Quoted message said:

That's true - the more tension you can bring to bear (before
destroying the rim) the better. Read "The Bicycle Wheel" by Jobst
Brandt.

i know that "high tension" recommendation is "in the book" and often
repeated here, but it's a fundamentally flawed piece of advice.

It's also a misquote. The technique Jobst describes is qualified to work only
with lightweight (430 g or less), 36 spoke rims.

Quoted message said:

the
closer a rim is operated to it's yield point, the less will be its
fatigue life, with the kind of results reported here yesterday:

http://mixednutsband.com/crack4.jpg

just because a rim doesn't fail with static load, doesn't mean it can
take the fatigue load. that's why there are so many reliability
complaint here on r.b.t.

Historically, the dominant wheel problems have been spoke breakage & wheels
coming out of true. Cracking of the spoke bed is strictly a matter of rim
design and spoke tension. For wheels like the one shown, the use of a
tensiometer would seem mandatory.

Quoted message said:

in addition, as can be seen in damon rinard's experiments, increasing
spoke tension makes absolutely no difference to lateral strength. see:

http://www.sheldonbrown.com/rinard/wheel/tension.gif

original page:
http://www.sheldonbrown.com/rinard/wheel/index.htm

I think you are confusing strength and stiffness. The rationale for high spoke
tension is that radial, not lateral, loads cause the spoke to lose tension, so
the spoke tension (& number of spokes) determines the load carrying capacity
of the wheel. If a wheel is loaded beyond that, the spokes may become
de-tensioned enough to either cause wheel collapse or nipple unscrewing.

Peter Cole said:

"jim beam" <[email hidden]> wrote

Quoted message said:

Jonesy wrote:

Quoted message said:

Quoted message said:

That's true - the more tension you can bring to bear (before
destroying the rim) the better. Read "The Bicycle Wheel" by Jobst
Brandt.

i know that "high tension" recommendation is "in the book" and often
repeated here, but it's a fundamentally flawed piece of advice.

It's also a misquote. The technique Jobst describes is qualified to work only
with lightweight (430 g or less), 36 spoke rims.

has he ever said that? i don't have his book in front of me; i can't
recall such a qualification, but i've seen jonsey's kind of statement
here many times.

Quoted message said:

Quoted message said:

the
closer a rim is operated to it's yield point, the less will be its
fatigue life, with the kind of results reported here yesterday:

http://mixednutsband.com/crack4.jpg

just because a rim doesn't fail with static load, doesn't mean it can
take the fatigue load. that's why there are so many reliability
complaint here on r.b.t.

Historically, the dominant wheel problems have been spoke breakage & wheels
coming out of true. Cracking of the spoke bed is strictly a matter of rim
design and spoke tension. For wheels like the one shown, the use of a
tensiometer would seem mandatory.

good observations.

Quoted message said:

Quoted message said:

in addition, as can be seen in damon rinard's experiments, increasing
spoke tension makes absolutely no difference to lateral strength. see:

http://www.sheldonbrown.com/rinard/wheel/tension.gif

original page:
http://www.sheldonbrown.com/rinard/wheel/index.htm

I think you are confusing strength and stiffness. The rationale for high spoke
tension is that radial, not lateral, loads cause the spoke to lose tension, so
the spoke tension (& number of spokes) determines the load carrying capacity
of the wheel. If a wheel is loaded beyond that, the spokes may become
de-tensioned enough to either cause wheel collapse or nipple unscrewing.

i've read the radial loading argument of high tension [and i know the
difference between strength & stiffness!]. regarding lateral loading,
this adds to the spoke pre tension on one side and subtracts from the
other. radial loads subtract only. if a spoke has a yield strength of
say 300kg, preloading it to 200kg only gives 100kg of lateral load
before yield. if the spokes have 100kg preload, it means they can take
twice as much lateral.

i want to be clear - i'm not advocating "too low tension" - i'm saying
that tension needs to be within spec, not this nebulous unscientific
concept of "as high as the rim can bear". agreed, too low tension can
lead to nipple unscrewing, but i guess that's why spoke manufacturers
sell threadlock & self-locking nipples.

"jim beam" <[email hidden]> wrote

Quoted message said:

Peter Cole said:

It's also a misquote. The technique Jobst describes is qualified to work

only

Quoted message said:

Quoted message said:

with lightweight (430 g or less), 36 spoke rims.

has he ever said that? i don't have his book in front of me; i can't
recall such a qualification, but i've seen jonsey's kind of statement
here many times.

I wrote that with the book in front of me, it's stated very clearly.

Quoted message said:

i've read the radial loading argument of high tension [and i know the
difference between strength & stiffness!].

OK, it's really the only argument Jobst makes.

Quoted message said:

regarding lateral loading,
this adds to the spoke pre tension on one side and subtracts from the
other. radial loads subtract only. if a spoke has a yield strength of
say 300kg, preloading it to 200kg only gives 100kg of lateral load
before yield. if the spokes have 100kg preload, it means they can take
twice as much lateral.

This lateral load argument doesn't really have any practical considerations.

Quoted message said:

i want to be clear - i'm not advocating "too low tension" - i'm saying
that tension needs to be within spec, not this nebulous unscientific
concept of "as high as the rim can bear". agreed, too low tension can
lead to nipple unscrewing, but i guess that's why spoke manufacturers
sell threadlock & self-locking nipples.

The more serious consequence is that the wheel can become unstable and buckle.

Peter Cole said:

"jim beam" <[email hidden]> wrote

Quoted message said:

Peter Cole said:

It's also a misquote. The technique Jobst describes is qualified to work

only

Quoted message said:

Quoted message said:

with lightweight (430 g or less), 36 spoke rims.

has he ever said that? i don't have his book in front of me; i can't
recall such a qualification, but i've seen jonsey's kind of statement
here many times.

I wrote that with the book in front of me, it's stated very clearly.

Quoted message said:

i've read the radial loading argument of high tension [and i know the
difference between strength & stiffness!].

OK, it's really the only argument Jobst makes.

Quoted message said:

regarding lateral loading,
this adds to the spoke pre tension on one side and subtracts from the
other. radial loads subtract only. if a spoke has a yield strength of
say 300kg, preloading it to 200kg only gives 100kg of lateral load
before yield. if the spokes have 100kg preload, it means they can take
twice as much lateral.

This lateral load argument doesn't really have any practical considerations.

the only consideration is that if the spoke tension is too high, the rim
is much more prone to taco. the only rim i've ever tacoed [not caused
by a car] was first ride immediately after i'd just built a wheel with
"tension as high as the rim can bear". downhill, bump, pretzel, long
walk home. the bump wasn't even enough to flat the tire.

Quoted message said:

Quoted message said:

i want to be clear - i'm not advocating "too low tension" - i'm saying
that tension needs to be within spec, not this nebulous unscientific
concept of "as high as the rim can bear". agreed, too low tension can
lead to nipple unscrewing, but i guess that's why spoke manufacturers
sell threadlock & self-locking nipples.

The more serious consequence is that the wheel can become unstable and buckle.

i would have thought that, but i rode mtb for the best part of a year
with a guy whose rear wheel was always making an irritating grinding
noise. eventually, i pursuaded him to let me take it home for
examination. i was shocked to find that all the spokes were so loose,
they were almost slack - the grinding was the spoke crossings moving
against each other as the hub "sank" relative to center on load - flat
spots on each spoke at that point. and the damnedest thing of all was
that this wheel was as true as i've ever seen!

he rides real hard & loves the fast bumpy downhill stuff, so there was
/plenty/ of opportunity for his wheel to have failed. this one instance
is not enough to demonstrate proof, but it's worth further investigation.

jim beam said:

Mark McMaster said:

jim beam said:

in addition, as can be seen in damon rinard's experiments, increasing
spoke tension makes absolutely no difference to lateral strength. see:

http://www.sheldonbrown.com/rinard/wheel/tension.gif

original page:
http://www.sheldonbrown.com/rinard/wheel/index.htm

Rinard's wheel test did not test (lateral) strength, as he stated in
his first paragraph: "I am measuring stiffness, not strength." His
test of measuring lateral stiffness at varying static spoke tension
mainly serves to confirm Hooke's Law.

hookes law merely states that deformation is directly proportional to
load below yield - the definition of elastic deformation. it's no
predictor of yield or modulus, both of which are measures of "strength".
by that same argument, increasing tension does not increase strength
just the same as it does not increase stiffness.

No argument. Rinard's test just shows that the existence of
a static pre-load doesn't change the wheel stiffness.

Quoted message said:

Quoted message said:

However, if you take a closer look at the graph, you'll notice that
the deflection increases dramatically when he backs the tension off
below a certain threshold. This increase in deflection shows a wheel
that is more likely to fail under load.

that's an assumption, not a fact. the deflection increases, for slack
spokes /because/ they're slack. if you're towing a car with a slack
rope, the distance between the two cars will increase until the rope
becomes taught. then the distance between the two cars is essentially
fixed and subject only to minor stretching of the rope - many orders of
magnitude less that slack take-up.

Poor analogy - as the the wheel is continued to be loaded
with slack spokes, there is no point when the spokes
suddenly start supporting the wheel.

Typical shallow section rims are not strong enough on their
own to support the momentary high loads often experienced
when cycling. The rim requires the support of the spokes.
Slackened spokes can no longer contribute support to the
spokes, and the rim must bear the load. Since the
unsupported rim can not bear as much load without damage, a
wheel low static spoke tension is more likely to be damaged
under a high momentary load.

Quoted message said:

Quoted message said:

Although Rinard is using a fixed load, it can be inferred from this
data that increased spoke tension can increase the strength of a wheel.

"inferred" how? the material does not change - this material still has
to obey hookes law until it yields. increasing load merely makes it
bend further. if you think about it, pre-tension serves to reduce the
load capacity of a component not increase it.

The graphs shows that at at some minimum tension, some of
the spokes slacken and no longer can contribute to
supporting the rim. It can be inferred that at a higher
static spoke tension, the spokes will not slacken until a
higher applied load. Since a wheel with all spokes still
under tension is a stronger wheel, than a wheel with higher
static spoke tension can support a higher load.

Quoted message said:

Quoted message said:

Indeed, you're supposition that "increasing spoke tension makes
absolutely no difference in lateral strength" is directly contradicted
by Rinard's conclusion from his test. From the web page referenced
above:

"A wheel whose spokes become slack while riding is a weak wheel,
because slack spokes cannot support the rim. This can be avoided to a
large extent by building wheels with tighter spokes. If spokes are
tighter initially, then the sudden increase in flexibility shown in
data points 9 and 10 is less likely to occur in use because a tighter
wheel can bear a higher load before spokes become slack."

there's no contradiction. the left part of the graph is essentially a
flat line. leftwards is increasing tension. once you're in the flat
line region, increasing tension is not increasing lateral stiffness.

There's more to it than simply stiffness. The sharp
decrease in stiffness occurs at the point when some of the
spokes no longer contribute to supporting the wheel. You
claim seem to claim spoke slackening make no difference in
wheel strength - Damon Rinard claims it does (and I agree
with him).

Mark McMaster
[email hidden]

jim beam <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

Peter Cole said:

"jim beam" <[email hidden]> wrote

Quoted message said:

Jonesy wrote:

Quoted message said:

>That's true - the more tension you can bring to bear (before
>destroying the rim) the better. Read "The Bicycle Wheel" by Jobst
>Brandt.

i know that "high tension" recommendation is "in the book" and often
repeated here, but it's a fundamentally flawed piece of advice.

It's also a misquote. The technique Jobst describes is qualified to work only
with lightweight (430 g or less), 36 spoke rims.

has he ever said that? i don't have his book in front of me; i can't
recall such a qualification, but i've seen jonsey's kind of statement
here many times.

It was a gross generalization. It was not meant to be definitive,
which is why I suggested further reading.

[snip]

Quoted message said:

i want to be clear - i'm not advocating "too low tension" - i'm saying
that tension needs to be within spec, not this nebulous unscientific
concept of "as high as the rim can bear".

If one was pedantic, they would say that "within spec" is "as high as
the rim can bear." But I was not being specific.

Quoted message said:

agreed, too low tension can
lead to nipple unscrewing, but i guess that's why spoke manufacturers
sell threadlock & self-locking nipples.

It seems to me that, on a properly-tensioned spoke with no wind-up,
threadlocking materials are completely unnecessary.

My apologies for not being more specific. After being berated for
being long-winded, I'm trying to cut down. I guess being specific has
some cost.

My intent was to steer the OP toward some reading materials. Mr.
Beam, if you would be so kind, why don't you assemble the tension
specs for rims such that you may in the future warn folks about
over-tensioning (past rim manufacturer's specs). That would be a
fantastic resource, and easier than arguing the theoretical materials
science behind your commentary - something that might not help a poor
wheelbuilder like myself.
--
Jonesy
--
Jonesy

Jonesy said:

jim beam <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

Peter Cole said:

"jim beam" <[email hidden]> wrote

>Jonesy wrote:

>>That's true - the more tension you can bring to bear (before
>>destroying the rim) the better. Read "The Bicycle Wheel" by Jobst
>>Brandt.
>
>i know that "high tension" recommendation is "in the book" and often
>repeated here, but it's a fundamentally flawed piece of advice.

It's also a misquote. The technique Jobst describes is qualified to work only
with lightweight (430 g or less), 36 spoke rims.

has he ever said that? i don't have his book in front of me; i can't
recall such a qualification, but i've seen jonsey's kind of statement
here many times.

It was a gross generalization. It was not meant to be definitive,
which is why I suggested further reading.

[snip]

Quoted message said:

i want to be clear - i'm not advocating "too low tension" - i'm saying
that tension needs to be within spec, not this nebulous unscientific
concept of "as high as the rim can bear".

If one was pedantic, they would say that "within spec" is "as high as
the rim can bear." But I was not being specific.

Quoted message said:

agreed, too low tension can
lead to nipple unscrewing, but i guess that's why spoke manufacturers
sell threadlock & self-locking nipples.

It seems to me that, on a properly-tensioned spoke with no wind-up,
threadlocking materials are completely unnecessary.

My apologies for not being more specific. After being berated for
being long-winded, I'm trying to cut down. I guess being specific has
some cost.

My intent was to steer the OP toward some reading materials. Mr.
Beam, if you would be so kind, why don't you assemble the tension
specs for rims such that you may in the future warn folks about
over-tensioning (past rim manufacturer's specs). That would be a
fantastic resource, and easier than arguing the theoretical materials
science behind your commentary - something that might not help a poor
wheelbuilder like myself.

funny you should say that!... thing is, i did start something like that
a while back, but i'm not "in the trade" so don't have the same easy
access to this info that a bike shop would. maybe appropriate tension
data for each can be added to damon's spoke calculator spreadsheet along
with rim erd's?

community project?

Mark McMaster said:

jim beam said:

Mark McMaster said:

jim beam wrote:

> in addition, as can be seen in damon rinard's experiments,
> increasing spoke tension makes absolutely no difference to lateral
> strength. see:
>
> http://www.sheldonbrown.com/rinard/wheel/tension.gif
>
> original page:
> http://www.sheldonbrown.com/rinard/wheel/index.htm

Rinard's wheel test did not test (lateral) strength, as he stated in
his first paragraph: "I am measuring stiffness, not strength." His
test of measuring lateral stiffness at varying static spoke tension
mainly serves to confirm Hooke's Law.

hookes law merely states that deformation is directly proportional to
load below yield - the definition of elastic deformation. it's no
predictor of yield or modulus, both of which are measures of
"strength". by that same argument, increasing tension does not
increase strength just the same as it does not increase stiffness.

No argument. Rinard's test just shows that the existence of a static
pre-load doesn't change the wheel stiffness.

Quoted message said:

Quoted message said:

However, if you take a closer look at the graph, you'll notice that
the deflection increases dramatically when he backs the tension off
below a certain threshold. This increase in deflection shows a wheel
that is more likely to fail under load.

that's an assumption, not a fact. the deflection increases, for slack
spokes /because/ they're slack. if you're towing a car with a slack
rope, the distance between the two cars will increase until the rope
becomes taught. then the distance between the two cars is essentially
fixed and subject only to minor stretching of the rope - many orders
of magnitude less that slack take-up.

Poor analogy - as the the wheel is continued to be loaded with slack
spokes, there is no point when the spokes suddenly start supporting the
wheel.

Typical shallow section rims are not strong enough on their own to
support the momentary high loads often experienced when cycling. The
rim requires the support of the spokes. Slackened spokes can no longer
contribute support to the spokes, and the rim must bear the load. Since
the unsupported rim can not bear as much load without damage, a wheel
low static spoke tension is more likely to be damaged under a high
momentary load.

check out my friend's slack spoked mtb wheel experience - with peter
cole in this same thread. heavy mtb use did _not_ damage a loose spoked
wheel.

Quoted message said:

Quoted message said:

Quoted message said:

Although Rinard is using a fixed load, it can be inferred from this
data that increased spoke tension can increase the strength of a wheel.

"inferred" how? the material does not change - this material still
has to obey hookes law until it yields. increasing load merely makes
it bend further. if you think about it, pre-tension serves to reduce
the load capacity of a component not increase it.

The graphs shows that at at some minimum tension, some of the spokes
slacken and no longer can contribute to supporting the rim. It can be
inferred that at a higher static spoke tension, the spokes will not
slacken until a higher applied load. Since a wheel with all spokes
still under tension is a stronger wheel, than a wheel with higher static
spoke tension can support a higher load.

how? wheels do not experience purely radial load. and with respect,
i'm not convinced you understand the graph. the high tension part is
essentially a flat line - there's no evidence of increasing tension
affecting wheel stiffness whatsoever, which is what you would expect
being as the material has not changed. is a compressed spring stiffer
than an uncompressed spring?

and stiffness is commonly regarded as a measure of perceived load
capacity, e.g. a wheel built with revos [which are very elastic] is
considered unsuitable for loaded touring.

Quoted message said:

Quoted message said:

Quoted message said:

Indeed, you're supposition that "increasing spoke tension makes
absolutely no difference in lateral strength" is directly
contradicted by Rinard's conclusion from his test. From the web page
referenced above:

"A wheel whose spokes become slack while riding is a weak wheel,
because slack spokes cannot support the rim. This can be avoided to a
large extent by building wheels with tighter spokes. If spokes are
tighter initially, then the sudden increase in flexibility shown in
data points 9 and 10 is less likely to occur in use because a tighter
wheel can bear a higher load before spokes become slack."

there's no contradiction. the left part of the graph is essentially a
flat line. leftwards is increasing tension. once you're in the flat
line region, increasing tension is not increasing lateral stiffness.

There's more to it than simply stiffness. The sharp decrease in
stiffness occurs at the point when some of the spokes no longer
contribute to supporting the wheel. You claim seem to claim spoke
slackening make no difference in wheel strength - Damon Rinard claims it
does (and I agree with him).

it makes no difference to lateral deflection while the spokes still have
tension - the flat line part of the graph!!! it's only when the spokes
are slack that any difference in lateral deflection is observed - just
like the tow rope analogy. that's why the graph has two distinct regions.

jim beam said:

Jonesy said:

My intent was to steer the OP toward some reading materials. Mr.
Beam, if you would be so kind, why don't you assemble the tension
specs for rims such that you may in the future warn folks about
over-tensioning (past rim manufacturer's specs). That would be a
fantastic resource, and easier than arguing the theoretical materials
science behind your commentary - something that might not help a poor
wheelbuilder like myself.

funny you should say that!... thing is, i did start something like that
a while back, but i'm not "in the trade" so don't have the same easy
access to this info that a bike shop would. maybe appropriate tension
data for each can be added to damon's spoke calculator spreadsheet along
with rim erd's?

community project?

I think it would be a good idea, whether or not the theory of "building
as tightly as the rim can stand it" is correct. In fact, I think it would
be interesting to compare the tension arrived at by the latter method to
the "official spec".

--
Benjamin Lewis

Seeing is deceiving. It's eating that's believing.
-- James Thurber