spoke breakage at nipple side



I've got some 14/15/14 double butted spokes laced to a chorus rear hub
and a Ritchey Aero OCR rim. I've broken two spokes since building the
wheel (about 2 thousand miles) and I've looked into it. It seems that
the spoke nipples are perpendicular to the rim, while the spokes enter
the rim at an angle (obviously). The end of the spoke nipple is
touching the outside of the spoke and the two spokes have broken where
the tread stops. The non-drive side are the ones breaking.

I'm pretty sure I have the spokes going to the proper hole in the rim
as the drive side looks fine. The spokes entering from the non-drive
side that are crossing on the outside have a distinct angle change
between the spoke and the nipple.

Why?

Should I remove the 8 spokes that are outside-crossing on the non-drive
side and drill the rim such that the nipple will be able to angle
towards the spokes?

Anything else I might be doing wrong?
 
[email protected] wrote:
> I've got some 14/15/14 double butted spokes laced to a chorus rear hub
> and a Ritchey Aero OCR rim. I've broken two spokes since building the
> wheel (about 2 thousand miles) and I've looked into it. It seems that
> the spoke nipples are perpendicular to the rim, while the spokes enter
> the rim at an angle (obviously). The end of the spoke nipple is
> touching the outside of the spoke and the two spokes have broken where
> the tread stops. The non-drive side are the ones breaking.
>
> I'm pretty sure I have the spokes going to the proper hole in the rim
> as the drive side looks fine. The spokes entering from the non-drive
> side that are crossing on the outside have a distinct angle change
> between the spoke and the nipple.
>
> Why?
>
> Should I remove the 8 spokes that are outside-crossing on the non-drive
> side and drill the rim such that the nipple will be able to angle
> towards the spokes?
>
> Anything else I might be doing wrong?


Is the rim new? I ran into this problem on a used rim that I bought and
built up. My suspicion was that the rim may have ben built with pulling
spokes in the opposite direction and that they had been seated in the
opposite direction, pulling or bending the ferrules slightly with them.
I have had success with using smooth-jaw pliers to grasp the nipples
and pull them over so that they would line up with the spoke.
Incredibly, it _seems_ to have worked, because I stopped breaking
spokes, but it may have just been serendipitous. (I did lubricate the
nipple threads and seats before the build.)

I think it's possible that regular "stress-relieving" may actually
exacerbate this problem by creating more of a kink at the point where
the spoke meets the nipple, localizing stress there. OTOH, maybe
stress-relieving with enough force should have lined up the nipples
with the spokes, although I can't visualize that effect- it seems to me
that the spoke should still kink at the nipple and stay kinked as more
force is applied.

This is mostly just theorizing over a correlation between straightening
the spoke line and a reduction in breakage. Brandt will no doubt jump
in now and tell me I am full of ****.
 
[email protected] wrote:
> There are no ferrules on the Ritchey Aero OCR rim, by the way.


There were, however, on my rim. Maybe your rim itself deformed, but you
yourself noted that the nipple was perpendicular to the rim and the
spoke was not. That's an issue whether or not the rim is new or used,
with or without ferrules.
 
[email protected] wrote:
> I've got some 14/15/14 double butted spokes laced to a chorus rear hub
> and a Ritchey Aero OCR rim. I've broken two spokes since building the
> wheel (about 2 thousand miles) and I've looked into it. It seems that
> the spoke nipples are perpendicular to the rim, while the spokes enter
> the rim at an angle (obviously). The end of the spoke nipple is
> touching the outside of the spoke and the two spokes have broken where
> the tread stops. The non-drive side are the ones breaking.
>
> I'm pretty sure I have the spokes going to the proper hole in the rim
> as the drive side looks fine. The spokes entering from the non-drive
> side that are crossing on the outside have a distinct angle change
> between the spoke and the nipple.
>
> Why?
>
> Should I remove the 8 spokes that are outside-crossing on the non-drive
> side and drill the rim such that the nipple will be able to angle
> towards the spokes?
>
> Anything else I might be doing wrong?
>

Some nipples align themselves in the rim better than others (they have
rounded seats).

If this doesn't happen, Jobst's book suggests deliberately bending the
spokes at the nipple during building to cold-set them and prevent any
movement in use, which can lead to fatigue.

If your wheel is 4x, rebuild it 3x.
 
Zog The Undeniable wrote:

> If this doesn't happen, Jobst's book suggests deliberately bending the
> spokes at the nipple during building to cold-set them and prevent any
> movement in use, which can lead to fatigue.


Interesting. The OP said that the spokes were on the non-drive side. I
don't see how it could be tensioned enough to prevent movement because
of the dish.
 
anonymous writes:

>> If this doesn't happen, Jobst's book suggests deliberately bending
>> the spokes at the nipple during building to cold-set them and
>> prevent any movement in use, which can lead to fatigue.


> Interesting. The OP said that the spokes were on the non-drive
> side. I don't see how it could be tensioned enough to prevent
> movement because of the dish.


Left rear spokes generally have a greater lateral angle than right
side spokes and because spokes do not break from tension (it causing
stresses far below yield), but rather residual stress overlayed on
even moderate tension, these spokes most often fail on a wheel that
has not been stress relieved.

This occurs both at elbows and threads because both places receive
bending during lacing and subsequent tensioning that reaches and
maintains yield stress.

Residual stress is the basic cause of spoke failure in bicycle wheels.

Jobst Brandt
 
[email protected] wrote:
> anonymous writes:
>
> >> If this doesn't happen, Jobst's book suggests deliberately bending
> >> the spokes at the nipple during building to cold-set them and
> >> prevent any movement in use, which can lead to fatigue.

>
> > Interesting. The OP said that the spokes were on the non-drive
> > side. I don't see how it could be tensioned enough to prevent
> > movement because of the dish.

>
> Left rear spokes generally have a greater lateral angle than right
> side spokes and because spokes do not break from tension (it causing
> stresses far below yield), but rather residual stress overlayed on
> even moderate tension, these spokes most often fail on a wheel that
> has not been stress relieved.
>
> This occurs both at elbows and threads because both places receive
> bending during lacing and subsequent tensioning that reaches and
> maintains yield stress.
>
> Residual stress is the basic cause of spoke failure in bicycle wheels.


Maybe, but in my case I did stress relieve the wheels to the best of my
ability, which involved using my heavy padded motorcycle gloves with
the rivets on the palm to squeeze the spoke pairs together with just
about all my strength, repeated until the process didn't change the
truing of the wheel. I was pretty frustrated by the whole thing and I
changed from alloy nipples to brass with little if any improvement. My
process of straightening the nipple-spoke line with pliers seems to
have fixed the problem. I admit that since I don't have anything to
check tension it is possible that tension was not high enough, but I
think it probably was.

It still seems to me that a kink in the spoke at the point where the
nipple and spoke meet would be the point where cyclical fatigue would
eventually result in failure if the spoke was flexed once per
revolution.

I never had a problem with spokes breaking in the wheels I built before
I had heard of stress-relieving but they did go out of true all the
time and seemed to dent more easily as well. I think that
stress-relieving is a part of building good wheels, but I am not
convinced that the spoke breakage problem in this case is caused by
residual stress that can be relieved by the normal method of stress
relief. Maybe using the pliers to straighten the spoke-nipple line is
another method of stress-relief that addresses this specific problem?
 
anonymous writes:

>>>> If this doesn't happen, Jobst's book suggests deliberately
>>>> bending the spokes at the nipple during building to cold-set them
>>>> and prevent any movement in use, which can lead to fatigue.


>>> Interesting. The OP said that the spokes were on the non-drive
>>> side. I don't see how it could be tensioned enough to prevent
>>> movement because of the dish.


>> Left rear spokes generally have a greater lateral angle than right
>> side spokes and because spokes do not break from tension (it
>> causing stresses far below yield), but rather residual stress
>> overlayed on even moderate tension, these spokes most often fail on
>> a wheel that has not been stress relieved.


>> This occurs both at elbows and threads because both places receive
>> bending during lacing and subsequent tensioning that reaches and
>> maintains yield stress.


>> Residual stress is the basic cause of spoke failure in bicycle wheels.


> Maybe, but in my case I did stress relieve the wheels to the best of
> my ability, which involved using my heavy padded motorcycle gloves
> with the rivets on the palm to squeeze the spoke pairs together with
> just about all my strength, repeated until the process didn't change
> the truing of the wheel. I was pretty frustrated by the whole thing
> and I changed from alloy nipples to brass with little if any
> improvement. My process of straightening the nipple-spoke line with
> pliers seems to have fixed the problem. I admit that since I don't
> have anything to check tension it is possible that tension was not
> high enough, but I think it probably was.


Well??? If the problem is fixed let's rejoice and chalk that up to
experience.

> It still seems to me that a kink in the spoke at the point where the
> nipple and spoke meet would be the point where cyclical fatigue
> would eventually result in failure if the spoke was flexed once per
> revolution.


I don't understand why you think that. Unsupported bends cause
failure but not supported kinks in the spoke. Without that kink, the
spoke was bending near the end of the threads with every wheel
revolution. With the kink, spokes just pull from the spoke nipple
rather than around a bend at an angle to the last support point.

> I never had a problem with spokes breaking in the wheels I built
> before I had heard of stress-relieving but they did go out of true
> all the time and seemed to dent more easily as well. I think that
> stress-relieving is a part of building good wheels, but I am not
> convinced that the spoke breakage problem in this case is caused by
> residual stress that can be relieved by the normal method of stress
> relief. Maybe using the pliers to straighten the spoke-nipple line
> is another method of stress-relief that addresses this specific
> problem?


You are probably correct in that assessment, but unsupported bends in
spokes cause spokes to bend. Such flexing readily puts high tensile
stress cycles in the outside surface of the bend and compressive
stress on the inside to cause fatigue failures.

Jobst Brandt
 
[email protected] wrote:
> I've got some 14/15/14 double butted spokes laced to a chorus rear hub
> and a Ritchey Aero OCR rim. I've broken two spokes since building the
> wheel (about 2 thousand miles) and I've looked into it. It seems that
> the spoke nipples are perpendicular to the rim, while the spokes enter
> the rim at an angle (obviously). The end of the spoke nipple is
> touching the outside of the spoke and the two spokes have broken where
> the tread stops. The non-drive side are the ones breaking.


I suspect the wheel is laced into the wrong holes. Look at the outside
of the rim. The holes are offset toward one side or the other. If off
set to the right, they are for spokes on the left side of the hub, as
the drilling process must be pointed that way.
 
[email protected] wrote:
> > It still seems to me that a kink in the spoke at the point where the
> > nipple and spoke meet would be the point where cyclical fatigue
> > would eventually result in failure if the spoke was flexed once per
> > revolution.

>
> I don't understand why you think that. Unsupported bends cause
> failure but not supported kinks in the spoke. Without that kink, the
> spoke was bending near the end of the threads with every wheel
> revolution. With the kink, spokes just pull from the spoke nipple
> rather than around a bend at an angle to the last support point.


I hadn't thought of the bend at the nipple as being supported- I was
thinking of it as cycling between supported and unsupported as the
spoke was wound up with each revolution of the wheel. I can see how a
bend there supported by the edge of the nipple, with sufficient tension
so that the bend is always supported, could work as you suggest. I can
also see how alloy nipples could be problematic in this situation
because they could deform and cause the bend to become unsupported. Are
you sure that tension can be high enough on the non-drive side to
always provide sufficient support to the bend? Or maybe this is an
indication that tension was not high enough.
 
I thought I might have laced them to the wrong hole as it's really hard
to tell which side of the asymmetrical rim the holes are on. It
certainly appears I have the holes in the rim which are slightly to the
right going to the left side of the hub, but it's really hard to say.
The nipples are slightly larger than the spoke, so the spokes going to
the right hand side are centered on the nipple. The nipples used for
the non-drive side are touching the left-hand side of the spokes.
There are breaking at that stress point.

Does anybody have this rim? If so, put the valve stem hole at the
bottom and tell me where does the first spoke towards the front of the
bike next to the valve stem go: to the cogset side or to the non-drive
side?
 
anonymous writes:

>>> It still seems to me that a kink in the spoke at the point where
>>> the nipple and spoke meet would be the point where cyclical
>>> fatigue would eventually result in failure if the spoke was flexed
>>> once per revolution.


>> I don't understand why you think that. Unsupported bends cause
>> failure but not supported kinks in the spoke. Without that kink,
>> the spoke was bending near the end of the threads with every wheel
>> revolution. With the kink, spokes just pull from the spoke nipple
>> rather than around a bend at an angle to the last support point.


> I hadn't thought of the bend at the nipple as being supported- I was
> thinking of it as cycling between supported and unsupported as the
> spoke was wound up with each revolution of the wheel. I can see how
> a bend there supported by the edge of the nipple, with sufficient
> tension so that the bend is always supported, could work as you
> suggest. I can also see how alloy nipples could be problematic in
> this situation because they could deform and cause the bend to
> become unsupported. Are you sure that tension can be high enough on
> the non-drive side to always provide sufficient support to the bend?
> Or maybe this is an indication that tension was not high enough.


If the spoke is bent as described in "the Bicycle Wheel" with
tensioned spokes, the bend, by definition, is resting against the
spoke nipple. Even if the spoke were to go slack intermittently, its
shape would always pull from the edge of the spoke nipple. With
aluminum spoke nipples, stress relieving would assure that spokes were
supported by the lip of the spoke nipple... assuming the spoke were
suitably bent. I think the pictures show that aspect.

Jobst Brandt
 
[email protected] wrote:
> I've got some 14/15/14 double butted spokes laced to a chorus rear hub
> and a Ritchey Aero OCR rim. I've broken two spokes since building the
> wheel (about 2 thousand miles) and I've looked into it. It seems that
> the spoke nipples are perpendicular to the rim, while the spokes enter
> the rim at an angle (obviously). The end of the spoke nipple is
> touching the outside of the spoke and the two spokes have broken where
> the tread stops. The non-drive side are the ones breaking.
>
> I'm pretty sure I have the spokes going to the proper hole in the rim
> as the drive side looks fine. The spokes entering from the non-drive
> side that are crossing on the outside have a distinct angle change
> between the spoke and the nipple.
>
> Why?
>
> Should I remove the 8 spokes that are outside-crossing on the non-drive
> side and drill the rim such that the nipple will be able to angle
> towards the spokes?
>
> Anything else I might be doing wrong?
>

imo, incorrect rim orientation is the most likely cause - from what i've
seen of these rims, they are drilled to orient spoke nipples to optimum,
so if yours are not, you're one spoke hole out.

as for bending spokes, it doesn't really address the issue. if you have
a bend, every time you increase or decrease tension. as you will in any
loading with use situation, you flex the bend, regardless of whether
that be visible or not. and any cyclic flex is still subject to
fatigue. get rim hole orientation right first, using a drill to
"assist" hole orientation if necessary. you should be fine after that.
try a diffeent brand of nipple if necessary. sapim are marginally
skinnier for example, and this will help. you don't mention brand of
spoke - fatigue life is primarily a function of spoke quality.

avoid excessive "stress relief". residual stress [such as it may be] is
compressive at the thread roots, so "relief" sufficient to yield these
thread roots will make fatigue worse, not better.
 
[email protected] wrote:
> I thought I might have laced them to the wrong hole as it's really hard
> to tell which side of the asymmetrical rim the holes are on. It
> certainly appears I have the holes in the rim which are slightly to the
> right going to the left side of the hub, but it's really hard to say.
> The nipples are slightly larger than the spoke, so the spokes going to
> the right hand side are centered on the nipple. The nipples used for
> the non-drive side are touching the left-hand side of the spokes.
> There are breaking at that stress point.
>
> Does anybody have this rim? If so, put the valve stem hole at the
> bottom and tell me where does the first spoke towards the front of the
> bike next to the valve stem go: to the cogset side or to the non-drive
> side?


Cogset side.