CXP-33 meltdown?

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

Quoted message said:

My rear wheel, Mavic CXP-33, 32 spokes, 2K miles, developed some noises.
The wheel had a slight wobble. Upon inspection, I discovered that
several spokes were quite loose - as in no tension at all. I tightened
them, but decided the next day to bring the bike in to the guy who had
built the wheels up for me.

He looked at the wheel, and said it was more than a "few" loose spokes,
that basically all of them were loose, and that all the spokes needed to
be brought down to zero tension, the wheel re-dished, etc. Sounds like
a wheel rebuild, basically!

My question is, what could have happened to this wheel? Was it not
built properly to begin with? FWIW, I'm about 170-180 lbs. I ride
over semi-rough Boston-area roads, but try to avoid major potholes. 23C
tires for the first 1.4K miles, switched to 25Cs subsequently.

Dave

Most likely insufficient/uneven tension and/or lack of pre-stressing in the
initial build. CXP33's are stout rims and shouldn't need a lot of attention
with 32 spokes. So the build job is a bit suspect, but the builder's at
least right in that it needs to be de-tensioned and redone. Basically a
rebuild without the relacing, yes. But you should never get to the point
where you're riding around on tensionless spokes anyway; you should make a
habit of checking the wheels once every few hundred miles for any
out-of-true spots and squeezing the spokes a bit to feel for variances in
tension. That way you catch problems before they get beyond what would only
require a few minutes' attention to sort out.

SB

<< My rear wheel, Mavic CXP-33, 32 spokes, 2K miles, developed some noises.
The wheel had a slight wobble. Upon inspection, I discovered that several
spokes were quite loose - as in no tension at all. I tightened them, but
decided the next day to bring the bike in to the guy who had
built the wheels up for me.

He looked at the wheel, and said it was more than a "few" loose spokes,
that basically all of them were loose, and that all the spokes needed to
be brought down to zero tension, the wheel re-dished, etc. Sounds like
a wheel rebuild, basically!

My question is, what could have happened to this wheel? Was it not
built properly to begin with? FWIW, I'm about 170-180 lbs. I ride
over semi-rough Boston-area roads, but try to avoid major potholes. 23C
tires for the first 1.4K miles, switched to 25Cs subsequently. >>
========
Sounds like a pretty poor wheel build...If spoke tension had been good up
front, and the spokes had been properly relieved, you shudda been able to ride
it, under normal circumstances, probably untouched,, 'til the sidewalls
caved...

JMHO...

PH

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

Quoted message said:

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

Quoted message said:

My rear wheel, Mavic CXP-33, 32 spokes, 2K miles, developed

some noises.

Quoted message said:

Quoted message said:

The wheel had a slight wobble. Upon inspection, I

discovered that

Quoted message said:

Quoted message said:

several spokes were quite loose - as in no tension at all. I

tightened

Quoted message said:

Quoted message said:

them, but decided the next day to bring the bike in to the

guy who had

Quoted message said:

Quoted message said:

built the wheels up for me.

He looked at the wheel, and said it was more than a "few"

loose spokes,

Quoted message said:

Quoted message said:

that basically all of them were loose, and that all the

spokes needed to

Quoted message said:

Quoted message said:

be brought down to zero tension, the wheel re-dished, etc.

Sounds like

Quoted message said:

Quoted message said:

a wheel rebuild, basically!

My question is, what could have happened to this wheel? Was

it not

Quoted message said:

Quoted message said:

built properly to begin with? FWIW, I'm about 170-180 lbs.

I ride

Quoted message said:

Quoted message said:

over semi-rough Boston-area roads, but try to avoid major

potholes. 23C

Quoted message said:

Quoted message said:

tires for the first 1.4K miles, switched to 25Cs

subsequently.

Quoted message said:

Quoted message said:

Dave

Most likely insufficient/uneven tension and/or lack of

pre-stressing in the

Quoted message said:

initial build. CXP33's are stout rims and shouldn't need a lot

of attention

Quoted message said:

with 32 spokes. So the build job is a bit suspect, but the

builder's at

Quoted message said:

least right in that it needs to be de-tensioned and redone.

Basically a

Quoted message said:

rebuild without the relacing, yes. But you should never get to

the point

Quoted message said:

where you're riding around on tensionless spokes anyway; you

should make a

Quoted message said:

habit of checking the wheels once every few hundred miles for

any

Quoted message said:

out-of-true spots and squeezing the spokes a bit to feel for

variances in

Quoted message said:

tension. That way you catch problems before they get beyond

what would only

Quoted message said:

require a few minutes' attention to sort out.

Why do you need to bring this wheel to zero tension? I would
just get it true and dished and then raise the tension to 100kgf
or so on the left side, making sure that tension was equal on all
spokes -- either by tone or tensiometer. Assuming that the spoke
threads/sockets are lubicated and that no gunk was used on the
orignal build, this should be a pretty simple job. -- Jay
Beattie.

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

Quoted message said:

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

Quoted message said:

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

Quoted message said:

My rear wheel, Mavic CXP-33, 32 spokes, 2K miles, developed

some noises.

Quoted message said:

Quoted message said:

The wheel had a slight wobble. Upon inspection, I

discovered that

Quoted message said:

Quoted message said:

several spokes were quite loose - as in no tension at all. I

tightened

Quoted message said:

Quoted message said:

them, but decided the next day to bring the bike in to the

guy who had

Quoted message said:

Quoted message said:

built the wheels up for me.

He looked at the wheel, and said it was more than a "few"

loose spokes,

Quoted message said:

Quoted message said:

that basically all of them were loose, and that all the

spokes needed to

Quoted message said:

Quoted message said:

be brought down to zero tension, the wheel re-dished, etc.

Sounds like

Quoted message said:

Quoted message said:

a wheel rebuild, basically!

My question is, what could have happened to this wheel? Was

it not

Quoted message said:

Quoted message said:

built properly to begin with? FWIW, I'm about 170-180 lbs.

I ride

Quoted message said:

Quoted message said:

over semi-rough Boston-area roads, but try to avoid major

potholes. 23C

Quoted message said:

Quoted message said:

tires for the first 1.4K miles, switched to 25Cs

subsequently.

Quoted message said:

Quoted message said:

Dave

Most likely insufficient/uneven tension and/or lack of

pre-stressing in the

Quoted message said:

initial build. CXP33's are stout rims and shouldn't need a lot

of attention

Quoted message said:

with 32 spokes. So the build job is a bit suspect, but the

builder's at

Quoted message said:

least right in that it needs to be de-tensioned and redone.

Basically a

Quoted message said:

rebuild without the relacing, yes. But you should never get to

the point

Quoted message said:

where you're riding around on tensionless spokes anyway; you

should make a

Quoted message said:

habit of checking the wheels once every few hundred miles for

any

Quoted message said:

out-of-true spots and squeezing the spokes a bit to feel for

variances in

Quoted message said:

tension. That way you catch problems before they get beyond

what would only

Quoted message said:

require a few minutes' attention to sort out.

Why do you need to bring this wheel to zero tension? I would
just get it true and dished and then raise the tension to 100kgf
or so on the left side, making sure that tension was equal on all
spokes -- either by tone or tensiometer. Assuming that the spoke
threads/sockets are lubicated and that no gunk was used on the
orignal build, this should be a pretty simple job. -- Jay
Beattie.

Thinking from the POV of the mech/builder, I'd want to make sure the owner
hadn't mucked it up too much - just eliminating an unknown variable. Easy
to just spin the spokes back to say, just where the threads start to show
and go back from there, and likely no more time-consuming than undoing
someone's mistakes. I don't know the OP's skill with a spoke wrench of
course, but I've seen many people cause more problems with one than they
solve when they encounter loose spokes.

SB

SB

Steve Blankenship said:

Thinking from the POV of the mech/builder, I'd want to make sure the owner
hadn't mucked it up too much - just eliminating an unknown variable. Easy
to just spin the spokes back to say, just where the threads start to show
and go back from there, and likely no more time-consuming than undoing
someone's mistakes. I don't know the OP's skill with a spoke wrench of
course, but I've seen many people cause more problems with one than they
solve when they encounter loose spokes.

The OP has trued wheels, but not for a long time. 😉 I just figured
that if they were floppy loose, tightening them to non-floppy-looseness
wouldn't hurt anything, and would probably help a bit. And it seemed
to: the noise diminished, and the wheels were less wobbly. Only rode
about 40 miles with that "fix" before bringing it, however.

It does seem like the spokes were not pre-tensioned during the build,
and stretched during use. I suppose properly tensioned spokes should
ring a bit when flicked with a finger, no?

Dave

Quoted message said:

My question is, what could have happened to this wheel?

I have several CXP 33 wheelsets and they are known to be among the most
reliable that exist. I do about 16500 km/year on these wheels, without any
spoke problem since 2-3 years....

Greets, Derk

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

Quoted message said:

Steve Blankenship said:

Thinking from the POV of the mech/builder, I'd want to make

sure the owner

Quoted message said:

Quoted message said:

hadn't mucked it up too much - just eliminating an unknown

variable. Easy

Quoted message said:

Quoted message said:

to just spin the spokes back to say, just where the threads

start to show

Quoted message said:

Quoted message said:

and go back from there, and likely no more time-consuming

than undoing

Quoted message said:

Quoted message said:

someone's mistakes. I don't know the OP's skill with a spoke

wrench of

Quoted message said:

Quoted message said:

course, but I've seen many people cause more problems with

one than they

Quoted message said:

Quoted message said:

solve when they encounter loose spokes.

The OP has trued wheels, but not for a long time. 😉 I just

figured

Quoted message said:

that if they were floppy loose, tightening them to

non-floppy-looseness

Quoted message said:

wouldn't hurt anything, and would probably help a bit. And it

seemed

Quoted message said:

to: the noise diminished, and the wheels were less wobbly.

Only rode

Quoted message said:

about 40 miles with that "fix" before bringing it, however.

It does seem like the spokes were not pre-tensioned during the

build,

Quoted message said:

and stretched during use. I suppose properly tensioned spokes

should

Quoted message said:

ring a bit when flicked with a finger, no?

Buy "The Bicycle Wheel" by Jobst Brandt. It will explain exactly
how spokes behave under tension. It also has a good section on
wheel building and truing. -- Jay Beattie.

Dave Stallard said:

Steve Blankenship said:

Thinking from the POV of the mech/builder, I'd want to make sure the owner
hadn't mucked it up too much - just eliminating an unknown variable. Easy
to just spin the spokes back to say, just where the threads start to show
and go back from there, and likely no more time-consuming than undoing
someone's mistakes. I don't know the OP's skill with a spoke wrench of
course, but I've seen many people cause more problems with one than they
solve when they encounter loose spokes.

The OP has trued wheels, but not for a long time. 😉 I just figured
that if they were floppy loose, tightening them to non-floppy-looseness
wouldn't hurt anything, and would probably help a bit. And it seemed
to: the noise diminished, and the wheels were less wobbly. Only rode
about 40 miles with that "fix" before bringing it, however.

It does seem like the spokes were not pre-tensioned during the build,
and stretched during use. I suppose properly tensioned spokes should
ring a bit when flicked with a finger, no?

Dave

Dear Dave,

As I understand it, the spoke-squeezing method of
stress-relief does not involve noticeable permanent
stretching, nor does any other part of wheel-building.

I think that the rim is expected to yield before the spoke
will stretch permanently.

If several spokes on a well-built wheel have mysteriously
gone completely loose, could the rim or the eyelets (if any)
be cracking?

I hope not, but it's worth a look.

Carl Fogel

<snip>

Quoted message said:

Most likely insufficient/uneven tension and/or lack of pre-stressing in the

initial build. CXP33's are stout rims and shouldn't need a lot of attention with 32 spokes. So the build job is a bit suspect, but the builder's at least right in that it needs to be de-tensioned and redone.
Basically a rebuild without the relacing, yes. But you should never get to
the point where you're riding around on tensionless spokes anyway; you
should make a habit of checking the wheels once every few hundred miles for
any out-of-true spots and squeezing the spokes a bit to feel for variances in
tension. That way you catch problems before they get beyondwhat would only require a few minutes' attention to sort out
Why do you need to bring this wheel to zero tension? I would
just get it true and dished and then raise the tension to 100kgf
or so on the left side, making sure that tension was equal on all
spokes -- either by tone or tensiometer. Assuming that the spoke
threads/sockets are lubicated and that no gunk was used on the
orignal build, this should be a pretty simple job. -- Jay
Beattie.[/QUOTE]

I agree with Jay Beattie, except the 100 kgf tension should be for each right side spoke... and I am sure what pre-stressing has nothing to do with it.
Stress relieving spokes helps lengthen their lives.
Even and correct spoke tension improves the durability and stability of the wheel.

Quoted message said:

Dave Stallard said:

Steve Blankenship said:

Thinking from the POV of the mech/builder, I'd want to make sure the owner
hadn't mucked it up too much - just eliminating an unknown variable. Easy
to just spin the spokes back to say, just where the threads start to show
and go back from there, and likely no more time-consuming than undoing
someone's mistakes. I don't know the OP's skill with a spoke wrench of
course, but I've seen many people cause more problems with one than they
solve when they encounter loose spokes.

The OP has trued wheels, but not for a long time. 😉 I just figured
that if they were floppy loose, tightening them to non-floppy-looseness
wouldn't hurt anything, and would probably help a bit. And it seemed
to: the noise diminished, and the wheels were less wobbly. Only rode
about 40 miles with that "fix" before bringing it, however.

It does seem like the spokes were not pre-tensioned during the build,
and stretched during use. I suppose properly tensioned spokes should
ring a bit when flicked with a finger, no?

Dave

Dear Dave,

As I understand it, the spoke-squeezing method of
stress-relief does not involve noticeable permanent
stretching, nor does any other part of wheel-building.

I think that the rim is expected to yield before the spoke
will stretch permanently.

If several spokes on a well-built wheel have mysteriously
gone completely loose, could the rim or the eyelets (if any)
be cracking?

I hope not, but it's worth a look.

Carl Fogel

hub holes yield as well as rims.

one of the problems with the cxp33 is that it's so strong & stiff, it's
easy to build a "true" wheel that has very un-uniform tension -
certainly the case here. the op needs to ensure the spokes are all
properly bedded in, then conduct the "ping" test for tension uniformity.

stallard-<< He looked at the wheel, and said it was more than a "few" loose
spokes,
that basically all of them were loose, and that all the spokes needed to
be brought down to zero tension, the wheel re-dished, etc >><BR><BR>
<< My question is, what could have happened to this wheel? Was it not
built properly to begin with? >><BR><BR>

My guess is that they were not the proper tension to start with.

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

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

Quoted message said:

My rear wheel, Mavic CXP-33, 32 spokes, 2K miles, developed some noises.
The wheel had a slight wobble. Upon inspection, I discovered that
several spokes were quite loose - as in no tension at all. I tightened
them, but decided the next day to bring the bike in to the guy who had
built the wheels up for me.

He looked at the wheel, and said it was more than a "few" loose spokes,
that basically all of them were loose, and that all the spokes needed to
be brought down to zero tension, the wheel re-dished, etc. Sounds like
a wheel rebuild, basically!

My question is, what could have happened to this wheel? Was it not
built properly to begin with? FWIW, I'm about 170-180 lbs. I ride
over semi-rough Boston-area roads, but try to avoid major potholes. 23C
tires for the first 1.4K miles, switched to 25Cs subsequently.

The wheel was built with insufficient spoke tension, I'd find a new
builder, or learn to do it myself, it's not very difficult.

jim beam said:

one of the problems with the cxp33 is that it's so strong & stiff, it's
easy to build a "true" wheel that has very un-uniform tension -
certainly the case here. the op needs to ensure the spokes are all
properly bedded in, then conduct the "ping" test for tension uniformity.

I wonder: does this stiffness affect the feel of the ride? Would the
Open Pro have a smoother-feeling ride?

Dave

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

Quoted message said:

jim beam said:

one of the problems with the cxp33 is that it's so strong & stiff, it's
easy to build a "true" wheel that has very un-uniform tension -
certainly the case here. the op needs to ensure the spokes are all
properly bedded in, then conduct the "ping" test for tension

uniformity.

Quoted message said:

I wonder: does this stiffness affect the feel of the ride? Would the
Open Pro have a smoother-feeling ride?

Nope.

Dave Stallard said:

jim beam said:

one of the problems with the cxp33 is that it's so strong & stiff,
it's easy to build a "true" wheel that has very un-uniform tension -
certainly the case here. the op needs to ensure the spokes are all
properly bedded in, then conduct the "ping" test for tension uniformity.

I wonder: does this stiffness affect the feel of the ride? Would the
Open Pro have a smoother-feeling ride?

Dave

having a wheel badly built in one instance is no reason to change equipment!

in answer to your question, the bigger rim certainly has better lateral
rigidity. as to feel of the ride, i fancy i can detect a smoother ride
on the open pro vs. a cxp14, a much bigger rim than the cxp33, but in
the absence of some accelerometer readings, i can't prove it. and a
number of folks will swear there's no difference. but the same people
can't tell the difference between a carbon fork & a steel fork either,
so i'm afraid you'll have to form your own opinion here dave.

jim beam said:

having a wheel badly built in one instance is no reason to change
equipment!

I certainly wasn't considering that! I just dithered for a long time
between Open Pros and CXP-33s, and so am always looking for reasons to
switch.

Quoted message said:

in answer to your question, the bigger rim certainly has better lateral
rigidity. as to feel of the ride, i fancy i can detect a smoother ride
on the open pro vs. a cxp14, a much bigger rim than the cxp33, but in
the absence of some accelerometer readings, i can't prove it. and a
number of folks will swear there's no difference. but the same people
can't tell the difference between a carbon fork & a steel fork either,
so i'm afraid you'll have to form your own opinion here dave.

Actually, this is a very interesting idea. I wonder if anyone has done
experiments in which accelerometers were used to measure the putative
smoothness or harshness of ride, using different equipment. Of course,
you'd have to use a constant course, constant rider, and constant
velocity for these experiments, but I bet it could be done.

Dave

Dave Stallard said:

Quoted message said:

one of the problems with the cxp33 is that it's so strong & stiff,
it's easy to build a "true" wheel that has very un-uniform tension
- certainly the case here. the op needs to ensure the spokes are
all properly bedded in, then conduct the "ping" test for tension
uniformity.

Quoted message said:

I wonder: does this stiffness affect the feel of the ride? Would
the Open Pro have a smoother-feeling ride?

These differences, although significant in metal loading and stress,
are about 100x smaller than tire deflection. On rough roads, these
deflections are completely lost in the bounce while on a smoothly
paved road the differences are less than riding over a sheet of copier
paper. If you can feel that, you may be able to detect it, but I have
not yet met anyone who can do that.

Jobst Brandt
[email hidden]

Dave Stallard said:

Actually, this is a very interesting idea. I wonder if anyone has
done experiments in which accelerometers were used to measure the
putative smoothness or harshness of ride, using different equipment.
Of course, you'd have to use a constant course, constant rider, and
constant velocity for these experiments, but I bet it could be done.

What people "feel" is what they hear. They are sure a wheel or tire
has less rolling resistance if they can hear either the spokes
resonating in the relative wind or the tires ringing to excitement
from pavement texture. Both are real but not perceptible other than
in sound. To make the measurement you mention would require excellent
differentiation between runs through equipment and varying surface.
This would require a good repeatable test bead.

Jobst Brandt
[email hidden]

Quoted message said:

Dave Stallard said:

Quoted message said:

one of the problems with the cxp33 is that it's so strong & stiff,
it's easy to build a "true" wheel that has very un-uniform tension
- certainly the case here. the op needs to ensure the spokes are
all properly bedded in, then conduct the "ping" test for tension
uniformity.

Quoted message said:

I wonder: does this stiffness affect the feel of the ride? Would
the Open Pro have a smoother-feeling ride?

These differences, although significant in metal loading and stress,
are about 100x smaller than tire deflection. On rough roads, these
deflections are completely lost in the bounce while on a smoothly
paved road the differences are less than riding over a sheet of copier
paper. If you can feel that, you may be able to detect it, but I have
not yet met anyone who can do that.

Jobst Brandt
[email hidden]

Dear Jobst,

Your sheet of paper example is the best thing that I've read
lately.

Thanks,

Carl Fogel