Measuring Spoke Tension?

Pete Cresswell said:

I've asked a couple of knowledgable people and they've said that you do it

by

Quoted message said:

ear. "Ping"....

Sounds ok for relative tension unless you have a tin ear (like Yours

Truly...).

Quoted message said:

But what about absolute tension? I have no idea at all what the right

tension

Quoted message said:

is except that it's "tight"....but reading the MTB wheel reviews I gather

that

Quoted message said:

for at least some wheels, there's such a thing as too-tight...

Some sort of gauge?

Stop fooling around and cough up 35 bucks for somebody who knows what

they're

Quoted message said:

doing?

What you want is called a "tensiometer." I think Park Tools sells one for about $50. It won't read
tension directly, but you can convert its reading into tension by using the included graphs and
knowing the spoke gauge in use.

Jobst's book "The Bicycle Wheel" gives a method for determining proper tension without using a
tensiometer. That method will work for all but deep aero rims.

Art Harris

(Pete Cresswell) said:

I've asked a couple of knowledgable people and they've said that you do it by ear. "Ping"....

Quoted message said:

Sounds ok for relative tension unless you have a tin ear (like Yours Truly...).

But what about absolute tension?

This can also be calculated from pitch to reasonable accuracy.

hyperphysics.phy-astr.gsu.edustring.htmlOpen ↗

Stainless steel has a relative density of about 8. Damp one of a crossed pair (and both spokes
hubside of the cross), and use the span of the other spoke between cross and nipple as the resonant
length. You'll need to measure the spoke gauge, and use a table to determine frequency from pitch.
Your tin ear might be a handicap.

Quoted message said:

I have no idea at all what the right tension is except that it's "tight"....but reading the MTB
wheel reviews I gather that for at least some wheels, there's such a thing as too-tight...

It was a cracking Mavic X517 (cracking at each drive-side eyelet) that led me to measure the spoke
tensions I'd achieved. Mavic recommends 90kgf per spoke. I'd reached 135.

James Thomson

Harris said:

Pete Cresswell said:

I've asked a couple of knowledgable people and they've said that you do it

by

Quoted message said:

ear. "Ping"....

Sounds ok for relative tension unless you have a tin ear (like Yours

Truly...).

Quoted message said:

But what about absolute tension? I have no idea at all what the right

tension

Quoted message said:

is except that it's "tight"....but reading the MTB wheel reviews I gather

that

Quoted message said:

for at least some wheels, there's such a thing as too-tight...

Some sort of gauge?

Stop fooling around and cough up 35 bucks for somebody who knows what

they're

Quoted message said:

doing?

What you want is called a "tensiometer." I think Park Tools sells one for about $50. It won't read
tension directly, but you can convert its reading into tension by using the included graphs and
knowing the spoke gauge in use.

Jobst's book "The Bicycle Wheel" gives a method for determining proper tension without using a
tensiometer. That method will work for all but deep aero rims.

Art Harris

Or, there's a link off Sheldon Brown's wheel building page to a page that gives you the pitch
that you should be getting as a function of spoke length (I don't have the link handy). You'll
need something that can generate the notes to compare it to (I used one of my kid's old toy
keyboards). In the absence of better information (like a well built wheel to compare it to 🙂),
it's a place to start.

David

Harris said:

Jobst's book "The Bicycle Wheel" gives a method for determining proper tension without using a
tensiometer. That method will work for all but deep aero rims.

It doesn't work well for lighter MTB rims with a single eyelet. I have a Mavic X517 with every
drive-side eyelet pulling out of the rim face. The tension I'd reached was 135kgf, with no sign of
the double wave in the rim. I later discovered that Mavic recommends a maximum tension of 100kgf.

James Thomson

Pete-<< But what about absolute tension? I have no idea at all what the right tension is except that
it's "tight"....but reading the MTB wheel reviews I gather that for at least some wheels, there's
such a thing as too-tight... >><BR><BR>

Jobst's book has a method to determine proper tension. A spoke tensionometer worrks quite well...LBS
have one??

Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
(303)440-3535 vecchios.comvecchios.comOpen ↗ "Ruote convenzionali costruite eccezionalmente bene"

RE/

Quoted message said:

Jobst's book has a method to determine proper tension. A spoke tensionometer worrks quite
well...LBS have one??

I visited a more techie LBS the other day and the guy there was adamant about the need to know
exactly what the spoke tension was. He even went so far as to say that the Mavic 517 failures I've
experienced were due soley to too much spoke tension. Seemed a little extreme to me considering the
number of people who report the same failures in the MTB reviews and the fact that each failed
wheels was built by a different (professional) builder. OTOH, considering the cavalier attitude of
the other builders I asked about absolute tension, maybe he has something.

I was tempted to ask him to build me another 517 - just to see - but wimped out and asked for a 618.
I've got another failed 517, however, and I think I'll take it to the same guy and ask for a
straight-up replacement just to get to the bottom of this...
-----------------------
PeteCresswell

I've been struggling over this question all week, as I just built three wheels following Jobst's
method to determine proper tension. When I checked tension with a tensiometer afterwards, I found
that the tension was nearly 150kgf on all the wheels.

One of the wheels (700c) uses as Specialized S-works (Hugi) hub on a Mavic MA2 rim.

The other two wheels have Mavic 618 rims and a Hugi 240 rear hub, XTR front hub.

I tightened them until stress relieving made them untrue, then backed off a bit. The final time I
stress-relieved them, they did not go out of true. I'd like to believe I did a good job on these,
but now I'm worried that they're too tight. Are there any disastrous consequences I might expect
from the wheels if they are, in fact, tighter than they should be?

BTW, where did you find Mavic's recommended maximum tension?

TIA Michael

In article <[email hidden]>, James Thomson

Quoted message said:

Harris said:

Jobst's book "The Bicycle Wheel" gives a method for determining proper tension without using a
tensiometer. That method will work for all but deep aero rims.

It doesn't work well for lighter MTB rims with a single eyelet. I have a Mavic X517 with every
drive-side eyelet pulling out of the rim face. The tension I'd reached was 135kgf, with no sign of
the double wave in the rim. I later discovered that Mavic recommends a maximum tension of 100kgf.

James Thomson

Pete Cresswell:

Quoted message said:

I visited a more techie LBS the other day and the guy there was adamant about the need to know
exactly what the spoke tension was. He even went so far as to say that the Mavic 517 failures I've
experienced were due soley to too much spoke tension.

What was the failure mode?

RE/

Quoted message said:

What was the failure mode?

Graceful.

I broke a spoke on one wheel and, in replacing it, noticed that the reflectiveness of the braking
surface varied around the spokes. Ran my finger over a spinning wheel and found out they were little
lumps. Then I started noticing the cracks around the spoke holes.....

Probally could have ridden both wheels for some time yet - but my guess was that eventually I'd be
walking home.

Both are rear wheels. No problems evident in the front wheels - which, I guess, disposes of the "too
much hard braking" argument....
-----------------------
PeteCresswell

Pete Cresswell said:

Quoted message said:

What was the failure mode?

Quoted message said:

Graceful.

Quoted message said:

I broke a spoke on one wheel and, in replacing it, noticed that the reflectiveness of the braking
surface varied around the spokes. Ran my finger over a spinning wheel and found out they were
little lumps. Then I started noticing the cracks around the spoke holes...

The irregularity on the braking surface is especially visible on rims that were entirely dark
anodized because the color wore off in lumps and valleys, small as these are. Th is has nothing to
do with rim cracking that is caused by cyclic stress of spoke tension. This tension varies on
average about 30% with each wheel revolution and causes surface cracks in the anodizing to propagate
into the rim metal.

Quoted message said:

Probably could have ridden both wheels for some time yet - but my guess was that eventually I'd be
walking home.

Spoke pullout is usually not a sudden failure but a gradual loss of alignment as individual spokes
go slack and even separate from the rim. This usually make the wheel useless before anything
significant fails.

Quoted message said:

Both are rear wheels. No problems evident in the front wheels - which, I guess, disposes of the
"too much hard braking" argument...

Theses spokes are probably mainly on the right side because these have higher stress and are closer
to the rim centerline, thereby experiencing greater stress cycles and at a higher mean stress than
the left spokes.

Jobst Brandt [email hidden] Palo Alto CA

Michael said:

I've been struggling over this question all week, as I just built three wheels following Jobst's
method to determine proper tension. When I checked tension with a tensiometer afterwards, I found
that the tension was nearly 150kgf on all the wheels.

Quoted message said:

One of the wheels (700c) uses as Specialized S-works (Hugi) hub on a Mavic MA2 rim.

Quoted message said:

The other two wheels have Mavic 618 rims and a Hugi 240 rear hub, XTR front hub.

Rims with a socket spanning the inner and outer walls are less likely to suffer problems than
single-eyelet rims like the 517. I've built MA2 rims to high tension using Jobst Brandt's method,
and have generally stopped tightening 618s when the nipples become hard to turn.

Quoted message said:

BTW, where did you find Mavic's recommended maximum tension?

tech-mavic.comCrossCountryOpen ↗
Jantes/General_Points/Condition_Use_Rim.pdf

tech-mavic.comCrossCountryOpen ↗ Jantes/GalJtesVTTXC/SpokeTension.pdf

"Respect appropriate tension of spokes. Mavic recommends tension of spokes between 70 - 90 kg.
Inappropriate tension of spokes can generate too much stress and damage the rim."

and

"Increase the tension of the spokes ... to reach a final tension of approximately 90 - 110 daN"

So the information is somewhat contradictory. Not only that, Mavic makes no distinction between
different models of rim, or different numbers of spokes. This makes some sense if you assume the
number to relate to pull-through tension in a single-eyelet rim.

James Thomson

James Thomson said:

Harris said:

Jobst's book "The Bicycle Wheel" gives a method for determining proper tension without using a
tensiometer. That method will work for all but deep aero rims.

It doesn't work well for lighter MTB rims with a single eyelet. I have a Mavic X517 with every
drive-side eyelet pulling out of the rim face. The tension I'd reached was 135kgf, with no sign of
the double wave in the rim. I later discovered that Mavic recommends a maximum tension of 100kgf.

James Thomson

And, at that tension they'll split in the inside between spokes because they're not rigid enough --
been there, done that...

David

Michael said:

I've been struggling over this question all week, as I just built three wheels following Jobst's
method to determine proper tension. When I checked tension with a tensiometer afterwards, I found
that the tension was nearly 150kgf on all the wheels.

One of the wheels (700c) uses as Specialized S-works (Hugi) hub on a Mavic MA2 rim.

The other two wheels have Mavic 618 rims and a Hugi 240 rear hub, XTR front hub.

I tightened them until stress relieving made them untrue, then backed off a bit. The final time I
stress-relieved them, they did not go out of true. I'd like to believe I did a good job on these,
but now I'm worried that they're too tight. Are there any disastrous consequences I might expect
from the wheels if they are, in fact, tighter than they should be?

BTW, where did you find Mavic's recommended maximum tension?

TIA Michael

In article <[email hidden]>, James Thomson

Quoted message said:

Harris said:

Jobst's book "The Bicycle Wheel" gives a method for determining proper tension without using a
tensiometer. That method will work for all but deep aero rims.

It doesn't work well for lighter MTB rims with a single eyelet. I have a Mavic X517 with every
drive-side eyelet pulling out of the rim face. The tension I'd reached was 135kgf, with no sign of
the double wave in the rim. I later discovered that Mavic recommends a maximum tension of 100kgf.

James Thomson

My LBS researched this for me before I built my last wheel and they were warned that Chris King
doesn't recommend going above 130 kgf because of deformation of the hub at the bearings. (The rim
maker -- DT Swiss -- said that if it doesn't taco, it'll take it 🙂). You also might have issues
with spokes ripping out of the hub on lower cross counts.

I ended up going to 125 🙂.

David

RE/

Quoted message said:

Spoke pullout is usually not a sudden failure but a gradual loss of alignment as individual spokes
go slack and even separate from the rim. This usually make the wheel useless before anything
significant fails.

I think I was there a couple of times already. One day I'd notice that the spokes seemed a little
loose and/or would find the wheel quite a bit out of alignment - as when I was toying with V brakes
on the rear and found the wheel offcenter *and* wobbly...
-----------------------
PeteCresswell

"(Pete Cresswell)" <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

RE/

Quoted message said:

Spoke pullout is usually not a sudden failure but a gradual loss of alignment as individual
spokes go slack and even separate from the rim. This usually make the wheel useless before
anything significant fails.

I think I was there a couple of times already. One day I'd notice that the spokes seemed a little
loose and/or would find the wheel quite a bit out of alignment - as when I was toying with V
brakes on the rear and found the wheel offcenter *and* wobbly...
-----------------------
PeteCresswell

i keep seeing the name Mavic pop up in reference to rim failure. a friend of mine told me after i
had purchsed my open pros that the spokes would pull through the eyelets in a short period of time
due to Mavics method of andonizing or hardening the aluminum. he said it left the rims super hard,
but brittle, so that there was no elasticity. im not sure if this is just due to Mavics popularity,
the fact that they are ridden hard, or because they actually are made too brittle, but when im
scavenging dumpsters from bike shops the overwhelming majority are Mavic. my open pro has not failed
yet after a year on my work bike, but its not reasurring to keep seeing trashed mavics on people's
bikes and in the garbage.

RE/

Quoted message said:

not sure if this is just due to Mavics popularity, the fact that they are ridden hard, or because
they actually are made too brittle, but when im scavenging dumpsters from bike shops the
overwhelming majority are Mavic.

I'm entertaining a third possibility: that they really are made in some way that they crack around
the spoke holes - but only when the spokes have more than a certain amount of tension on them. The
tension factor was put forth by one LBS owner I asked. He also happened to be the only one I met who
has spend the $300 or so on a tensionometer.

Could just be an unfortunate design/marketing combination were they put out a product that *really*
needed to be set up a certain way - but which whose consumers/builders didn't have the means or
inclination to do it the specified way.

In the MTB reviews there are over 130 reviews of the 517. Lotta reviewers trashed it - but there's a
significant number who swear by the things. Also some relative lightweights who had failures that
seem more common to the 200+ riders.

-----------------------
PeteCresswell