wheelbuilding question

Mavic Reflex rims - 90kgf
Zipp (newer style without the carbon weave) - 100 kgf
Zipp (older with carbon weave) - 80 kgf
I have built many Zipps and Mavics so I thought it might be nice to check
with the mfg. Zipp has it posted on their site. If you want any other rim
tension recommendation just go to their website a nd contact them. They are
happy to tell you.
Eric

On Sun, 11 Jul 2004 15:27:36 -0700, jim beam <[email hidden]>

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.

I'm having a hard time matching my experience with this. I've seen
plenty of collapsed wheels where none of the spokes yielded - the
wheels pretzeled first. So I don't see that high initial build tension
could cause spokes to yield in a lateral overload situation.

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,

Agreed.

Quoted message said:

not this nebulous unscientific
concept of "as high as the rim can bear".

A broad definition of the phrase "as high as the rim can bear" might
include "...as high as the rim can bear in fatigue as well as gentle
waves during stress relief", but I don't see how I could determine
fatigue effects without experimental results. So I also rely on
manufacturer's specs, when they're given. :-)

There are other practical limits in some wheels too. Nipples rounding,
spokes twisting up, hub flanges breaking, maybe some others. Too tight
might mean to tight for any number of limits, and these might vary
from wheel to wheel.

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.

Amazing how well these work, too!

dianne_1234 said:

On Sun, 11 Jul 2004 15:27:36 -0700, jim beam <[email hidden]>

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.

I'm having a hard time matching my experience with this. I've seen
plenty of collapsed wheels where none of the spokes yielded - the
wheels pretzeled first. So I don't see that high initial build tension
could cause spokes to yield in a lateral overload situation.

that's my experience also. i'm just arguing theory about lateral
loading having an additive element as well as subtractive - you'd never
look at one spoke in isolation either.

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,

Agreed.

Quoted message said:

not this nebulous unscientific
concept of "as high as the rim can bear".

A broad definition of the phrase "as high as the rim can bear" might
include "...as high as the rim can bear in fatigue as well as gentle
waves during stress relief",

agreed.

Quoted message said:

but I don't see how I could determine
fatigue effects without experimental results. So I also rely on
manufacturer's specs, when they're given. :-)

you can do finite element modeling for fatigue, but it's generally an
academic exercise - reliable results come from experimentation.

Quoted message said:

There are other practical limits in some wheels too. Nipples rounding,
spokes twisting up, hub flanges breaking, maybe some others. Too tight
might mean to tight for any number of limits, and these might vary
from wheel to wheel.

yup. the whole business of fatigue analysis is statistical.

Quoted message said:

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.

Amazing how well these work, too!

i've never used them myself. please tell more! do they really keep a
wheel truer?

Benjamin Lewis said:

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".

i agree.

it's not scientific because i couldn't get readings, but i built a mtb
wheel with a mavic x618 rim. that rim cranked up to tensions so high,
the readings on my park tensiometer were off the chart.

Eric said:

Mavic Reflex rims - 90kgf
Zipp (newer style without the carbon weave) - 100 kgf
Zipp (older with carbon weave) - 80 kgf
I have built many Zipps and Mavics so I thought it might be nice to check
with the mfg. Zipp has it posted on their site. If you want any other rim
tension recommendation just go to their website a nd contact them. They are
happy to tell you.
Eric

thanks eric! ok, i guess we have some momentum. any others, please
post here - i'll tabulate & email to damon rinard for inclusion in spoke
calc.

jim beam said:

Peter Cole said:

The technique Jobst describes is qualified to work only
with lightweight (430 g or less), 36 spoke rims.

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".

In wheels with more than 36 spokes, often the maximum practiceable
tension is barely enough. 48 hole 700c rims below about 500g begin to
collapse at a spoke tension that feels low on cursory inspection.

Recent MTB practice of lacing very heavy rims with only 32 spokes
makes for a situation where other factors limit spoke tension, but
such wheels seem structurally quite sub-optimal, particularly with
regard to lateral stiffness but also in ease of service.

My thinking is that if a rim can support normal spoke tension (100-150
kgf) but a little more causes the rim to collapse, then the spoke
count and rim section are well matched. Too light a rim for the spoke
count and the spokes will be undertensioned, thus yielding a heavy
wheel with the failure strength of a light one. Too heavy a rim for
the spoke count, as is the current fashion, yields a heavy wheel with
the lateral rigidity of a light one.

Chalo Colina

On Tue, 13 Jul 2004 21:11:54 -0700, jim beam <[email hidden]>

Quoted message said:

Quoted message said:

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.

Amazing how well these work, too!

i've never used them myself. please tell more! do they really keep a
wheel truer?

In my experience, under-tensioned wheels can stay true for years if
the nipples are fixed against loosening.

Rolf Vector Pros have nylock nuts for nipples, but their high tension
might also have something to do with most of them staying true for
long periods.

Rolf Vector Comps used LocTite in the nipples. They stayed true
"forever" unless you got a wheel with insufficient LocTite. Those were
easy to fix by adding LocTite.

Bontrager wheels use DT's prolock nipples. Occasionally some spokes
are frighteningly loose, yet the wheels generally stay true.

Mavic uses Alpina's locking nipple (ABS = Alpina Blocking System, I
think). There are several testimonials from riders in this newsgroup
that their Mavic wheels stay true.

Campagnolo uses a nylock type nut for the nipples in many of their
wheels.

Wheelsmith spokeprep has kept many of the wheels I built years ago
true. This is even before I knew about "proper" (high) spoke tension.

If you can keep the nipples from turning while riding, then pretty
much only damaged components can take the wheel out of true.

dianne_1234 said:

On Tue, 13 Jul 2004 21:11:54 -0700, jim beam <[email hidden]>

Quoted message said:

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.

Amazing how well these work, too!

i've never used them myself. please tell more! do they really keep a
wheel truer?

In my experience, under-tensioned wheels can stay true for years if
the nipples are fixed against loosening.

Rolf Vector Pros have nylock nuts for nipples, but their high tension
might also have something to do with most of them staying true for
long periods.

Rolf Vector Comps used LocTite in the nipples. They stayed true
"forever" unless you got a wheel with insufficient LocTite. Those were
easy to fix by adding LocTite.

Bontrager wheels use DT's prolock nipples. Occasionally some spokes
are frighteningly loose, yet the wheels generally stay true.

Mavic uses Alpina's locking nipple (ABS = Alpina Blocking System, I
think). There are several testimonials from riders in this newsgroup
that their Mavic wheels stay true.

Campagnolo uses a nylock type nut for the nipples in many of their
wheels.

Wheelsmith spokeprep has kept many of the wheels I built years ago
true. This is even before I knew about "proper" (high) spoke tension.

If you can keep the nipples from turning while riding, then pretty
much only damaged components can take the wheel out of true.

very very interesting. thinking about it, that accords with the
situation on my friend's loose mtb wheel. i know the guy that built it
used wheelsmith spoke prep which is supposed to lock the threads after
assembly, and that thing was absolutely straight as an arrow even though
it was almost completely slack. thanks dianne.

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

Quoted message said:

Benjamin Lewis said:

jim beam said:

Jonesy wrote:

>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".

i agree.

it's not scientific because i couldn't get readings, but i built a mtb
wheel with a mavic x618 rim. that rim cranked up to tensions so high,
the readings on my park tensiometer were off the chart.

I have another anecdotal story for you:

My X618 rear drive-side spokes were so tight that I started to see
evidence in the rim of eyelet pull-out. The only way it could be
detected was by shining very strong light along the rim on the drive
side. Every other eyelet had a very minor bulge, corresponding to a
drive side spoke. I backed all the spokes off one-half turn, and they
are still very highly tensioned.

An interesting data point: On the front wheel, the rotor-side spokes
protruded past the end of the nipple by about 1mm, while the
right-hand side spoke ends remained below the level of slot. On the
rear wheel, neither set of spokes had ends that came up to the level
of the nipple slots.

I rode around and did my best to put side loads on the wheels. No
noises at all, nothing to indicate nipple unscrewing, etc. Took the
wheels off and put them back on the stand, and they seemed to be just
as good as when I declared them "good enough". As in <1mm lateral
run-out and <0.5mm radial run-out "good enough".

I have no doubt that these wheels will last, after comparing the
tensions of these spokes to some machine-built wheels that I had lying
around. Ones that had been ridden on for a couple of years without
any mishaps.

Frankly, building disk-brake wheels with swaged (butted) spokes was
almost as easy as building regular wheels. They didn't just "fall
together", but it wasn't as fiddly as I imagined it would be.
--
Jonesy

Jonesy said:

...
I rode around and did my best to put side loads on the wheels....

How does one do this on a single-track vehicle?

--
Tom Sherman – Quad City Area

Tom Sherman said:

Jonesy said:

...
I rode around and did my best to put side loads on the wheels....

How does one do this on a single-track vehicle?

by avoiding roads covered with black ice 😉
/Marten

Tom Sherman said:

Jonesy said:

I rode around and did my best to put side loads on the wheels....

How does one do this on a single-track vehicle?

Get out of the plane of the bike, so you lean to one side and the bike
leans to the other, with your CoG (obviously) still above the wheel track?
--
David Damerell <[email hidden]> Distortion Field!

Tom Sherman <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

Jonesy said:

...
I rode around and did my best to put side loads on the wheels....

How does one do this on a single-track vehicle?

I am assuming you are asking a serious question.

Every turn you make generates some side load on the wheel. Otherwise
you wouldn't turn. Have you ever seen cyclists who move the bike from
side to side as they pedal? That also generates wheel side-loading.
I did side-to-side hops, hard turns, and the pedalling I describe.

I'm not sure if my regular MTB trails would put as much stress on the
wheels, but that test is next.

--
Jonesy

"Eric" <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

Mavic Reflex rims - 90kgf
Zipp (newer style without the carbon weave) - 100 kgf
Zipp (older with carbon weave) - 80 kgf
I have built many Zipps and Mavics so I thought it might be nice to check
with the mfg. Zipp has it posted on their site. If you want any other rim
tension recommendation just go to their website a nd contact them. They are
happy to tell you.
Eric

How many spokes?

Jonesy said:

Tom Sherman <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

Jonesy said:

...
I rode around and did my best to put side loads on the wheels....

How does one do this on a single-track vehicle?

I am assuming you are asking a serious question.

Every turn you make generates some side load on the wheel. Otherwise
you wouldn't turn. Have you ever seen cyclists who move the bike from
side to side as they pedal? That also generates wheel side-loading.
I did side-to-side hops, hard turns, and the pedalling I describe.

I'm not sure if my regular MTB trails would put as much stress on the
wheels, but that test is next.

However, when a single-track vehicle is leaned to one side, it also
turns in that direction, greatly reducing the lateral loadings on the
wheels. While these cycling maneuvers will certainly produce some
lateral loading to the wheels, the magnitude would not be that great.

If you want to put some significant lateral loads on a spoked wheel, I
suggest cornering at high speed on tadpole trike with a low center of
gravity.

--
Tom Sherman – Quad City Area

jim beam said:

Mark McMaster said:

jim beam said:

Mark McMaster wrote:

> 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.

(Sorry for the late reply - I was away on business last
week.) You have just hit upon the exact reason that spoke
tension affects wheel strength. I think we agree that in
some situations, forces on the wheel during riding can
exceed the yield strength of the rim - for example, hitting
a bump or pothole hard enough can bend the rim. For the rim
to bend, it has to strain (deflect) beyond it's yield point.

As you point out, what Rinard's graph shows us is that when
loaded, there are two distinct regions of deflection - a
high stiffness (low deflection) region when all the spokes
remain tight, and low stiffness (high deflection) region
when some of the spokes slacken. With loose spokes, the
majority of the load is taken up in the low stiffness
region, where there is high deflection for a given load.
With tighter spokes, more of the load is taken up in the
high stiffness, low deflection region, so the total
deflection for a given load will be less. With higher spoke
tension, a higher load is required to reach the yield point
of the rim.

Obviously there are other factors that may limit to how high
the spoke tension can be for a given wheel. But it clearly
apparent that the static spoke tension plays a vital role in
determining the load required to yield the rim.

Mark McMaster
[email hidden]

jim beam said:

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.

(Sorry for the late reply - was traveling on business last
week.) This argument falls down for several reasons.
Firstly, because of the geometry of the wheel, a lateral
load on wheel does not create a proportional load on the
spokes (i.e., a 100 kg side load does produce a 100 kg
change in spoke tension). Secondly, for the vast majority
of wheels, the rim will fail (yield) well before any spokes
do (even in a highly tensioned wheel). And finally, lateral
loads are not present without radial loads - and as we all
know, radial loads serve to lower spoke tension, not raise
it. In standard bicycle wheels, spoke yield strength is not
the limiter on static spoke tension.

Mark McMaster
[email hidden]

Tom Sherman <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

Jonesy said:

Tom Sherman <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

Jonesy wrote:

>...
>I rode around and did my best to put side loads on the wheels....

How does one do this on a single-track vehicle?

I am assuming you are asking a serious question.

Every turn you make generates some side load on the wheel. Otherwise
you wouldn't turn. Have you ever seen cyclists who move the bike from
side to side as they pedal? That also generates wheel side-loading.
I did side-to-side hops, hard turns, and the pedalling I describe.

I'm not sure if my regular MTB trails would put as much stress on the
wheels, but that test is next.

However, when a single-track vehicle is leaned to one side, it also
turns in that direction, greatly reducing the lateral loadings on the
wheels.

No. You are assuming that I am keeping my COG in line with the top
tube and down tube. I am not. I can ride a bike (coasting, not
pedalling) with the bike angled as much as 30 degrees from the
vertical while moving in a straight line. In addition, I can steer in
the opposite direction of the lean. The only thing that matters is
COG WRT wheel track. I can lean the bike and keep my COG over the
wheel track easily, such that the top tube is resting on my inner
thigh. It can go even further if I bend my legs properly. These are
not an easy positions to maintain, but they can be done.

Quoted message said:

While these cycling maneuvers will certainly produce some
lateral loading to the wheels, the magnitude would not be that great.

No, trail riding is better for that. It passed that test as well -
rocks, roots and all.

Quoted message said:

If you want to put some significant lateral loads on a spoked wheel, I
suggest cornering at high speed on tadpole trike with a low center of
gravity.

That would do it. 🙂
--
Jonesy