Spoke head popped off

[Anthony DeLorenzo]

Hi All,

While riding this weekend I broke a spoke. I found it odd that the
spoke head basically popped off. The entire spoke, including the elbow
section, was intact.

These are 36-spoke wheels with less than 1000 km on them. Is this a
normal area for a spoke to fail from stress? Or is it just a bad
spoke? Otherwise the wheel has been trouble-free so far.

Regards,
Anthony

 

[Bruce Gilbert]

"Anthony DeLorenzo" <[email protected]> wrote in message
news:[email protected]...
> Hi All,
>
> While riding this weekend I broke a spoke. I found it odd that the
> spoke head basically popped off. The entire spoke, including the elbow
> section, was intact.
>
> These are 36-spoke wheels with less than 1000 km on them. Is this a
> normal area for a spoke to fail from stress? Or is it just a bad
> spoke? Otherwise the wheel has been trouble-free so far.
>
> Regards,
> Anthony

I have had this happen a few times. Mass produced, small metal parts, slight
internal defect, put it together. Get a new nipple installed and do not
worry...

Bruce

 

[jim beam]

Anthony DeLorenzo wrote:
> Hi All,
>
> While riding this weekend I broke a spoke. I found it odd that the
> spoke head basically popped off. The entire spoke, including the elbow
> section, was intact.
>
> These are 36-spoke wheels with less than 1000 km on them.

in this day and age, that indicates a low-end cheapo wheelset, and thus
inferior spoke quality.


> Is this a
> normal area for a spoke to fail from stress? Or is it just a bad
> spoke? Otherwise the wheel has been trouble-free so far.

it happens - it's a function of spoke quality. simply replace with a
known brand you can get from your lbs, then enjoy. [several more may
fail if the wheel is not re-spoked, and unless you do that yourself, it
may not be economic vs. buying new wheels.]

 

[daveornee]

Hi All,

While riding this weekend I broke a spoke. I found it odd that the
spoke head basically popped off. The entire spoke, including the elbow
section, was intact.

These are 36-spoke wheels with less than 1000 km on them. Is this a
normal area for a spoke to fail from stress? Or is it just a bad
spoke? Otherwise the wheel has been trouble-free so far.

Regards,
Anthony

Sapim says:
"The spoke head breaks off (this is unusual)
- Bad positioning of the head in the hub (e.g. a slant position puts all the pressure on one side of the bottom of the spoke head. As a result the head snaps off, the so-called "bottle cap effect").
- The hub flange is too thick and is not suited to the length of the spoke bend (i.e. all the pressure is on the head, which will be excessively stressed and rip off).
- If the wrong cross pattern is chosen, e.g. cross 4 on large flange hubs, the spoke bend can rub against the adjacent spoke head. This should be avoided."
I have never had it happen in over 500,000 miles of riding, but I have seen it in a couple of wheels.

 

[Anthony DeLorenzo]

On May 20, 5:59 am, jim beam <[email protected]> wrote:

> in this day and age, that indicates a low-end cheapo wheelset, and thus
> inferior spoke quality.

Not the case here... These are DT Competition spokes laced to XT hubs.

 

[Anthony DeLorenzo]

On May 20, 6:24 am, daveornee <daveornee.39p...@no-
mx.forums.cyclingforums.com> wrote:

> Sapim says:
> "The spoke head breaks off (this is unusual)
> - Bad positioning of the head in the hub (e.g. a slant position puts
> all the pressure on one side of the bottom of the spoke head. As a
> result the head snaps off, the so-called "bottle cap effect").
> - The hub flange is too thick and is not suited to the length of the
> spoke bend (i.e. all the pressure is on the head, which will be
> excessively stressed and rip off).
> - If the wrong cross pattern is chosen, e.g. cross 4 on large flange
> hubs, the spoke bend can rub against the adjacent spoke head. This
> should be avoided."
> I have never had it happen in over 500,000 miles of riding, but I have
> seen it in a couple of wheels.

Thanks for that. Looking at that list, the first one is a good
possibility. I built these wheels myself and may have had a spoke head
that wasn't quite bedded in to the hub correctly. I'll take a look at
the wheel closer, but the replacement spoke was fine over the next 400
km of our ride.

 

[Tom Kunich]

"Anthony DeLorenzo" <[email protected]> wrote in message
news:[email protected]...
> Hi All,
>
> While riding this weekend I broke a spoke. I found it odd that the
> spoke head basically popped off. The entire spoke, including the elbow
> section, was intact.
>
> These are 36-spoke wheels with less than 1000 km on them. Is this a
> normal area for a spoke to fail from stress? Or is it just a bad
> spoke? Otherwise the wheel has been trouble-free so far.

There are bad spokes in every lot. It would be prohibitively expensive to
inspect spokes as well as necessary to prevent the very occasional failure
of this kind.

Replace the spoke. If a second spoke breaks start looking for problems such
as bad die for forming the heads - it will leave marks.

 

[jim beam]

Anthony DeLorenzo wrote:
> On May 20, 5:59 am, jim beam <[email protected]> wrote:
>
>> in this day and age, that indicates a low-end cheapo wheelset, and thus
>> inferior spoke quality.
>
> Not the case here... These are DT Competition spokes laced to XT hubs.

in that case, all you can do is replace - statistically, it won't happen
again before the wheel's worn out.

fwiw, sapim have a much larger radius under their spoke heads than d.t.,
so should be much less prone to this kind of fatigue.