_ForceD_

In almost 40 years of riding bikes, and doing all my own maintenance, I can't recall it happening this way. Usually the spoke parts at the spoke head. Not the nipple parting.





Dan

Bill Kapaun

Classic sign of a spoke that's too short.

_ForceD_

I suppose usually it would be. In this case, (with the replacement nip), the spoke threads came right to the top of the nipple head...if not a bit more.

Dan

Bill Kapaun

It's pretty obvious the "button" wasn't supporting the spoke on this broken nipple.
Nipples come in different threading lengths.
Are the other nipples giving the same engagement as the new one?
Or did you over tighten this spoke, relative to the other spokes which may be under tensioned. Is the wheel still true?

_ForceD_

Can't see it on my my blurry photo, but looking at the threads on the 'button' it looks like the spoke pulled the last thread or two closest to the break out (i.e. striped it). But yeah...wheel is true. I tightened the replacement with my tensionometer to match that of the other drive-side spokes...and that just about put it back to true. In the truing stand it only needed minor tweeking to get within about 1mm.

Dan

fietsbob

put another nip on . and see if it lasts any longer..

pdlamb

I hate to sound like a software engineer (try it again and see if the same thing happens), but that's probably the best option. I'm guessing a one in 5,000 manufacturing defect in the nipple cause the break.

davidad

In 262k miles I have not seen that problem. I built one wheel with Al. nipples and they broke when I tweaked the lateral true. I replaced them and had no more problems.

JohnDThompson 

I had it happen to two spokes on one wheel, but it was a result of unusual circumstances. The rider in front of me hit a putty knife that was lying in the road, it flipped into the air and landed in my front wheel, then jammed at the fork, breaking the nipples off. Just as well that they broke, otherwise I surely would have done a face-plant. As it was, I suffered no injuries but had to make the Call of Shame. Replaced the broken nipples the next day and put the wheel back in service. That was several years ago; still holding up fine.

_ForceD_

Just to be clear, I recreated approximately what I was presented with. About that much spoke thread was exposed when the button/head broke off. I didn't have to replace the spoke...jus the nipple. I had to shake the button out of the innards of the rim. With a magnifying glass I can see that it looks like the threads in the button are striped.

TiHabanero

JohnDThompson, that is a weird one.

pdlamb

Yes, put that one in the dictionary under "freak accident!"

@Forced, I wouldn't put too much emphasis on the last couple threads being damaged. That's probably the result of the nipple breaking. All the load of the spoke then went into the head of the nipple, and two threads remaining weren't enough to carry the load, so it pulled out. I'd bet the remaining interior threads look even worse!

cyccommute 

It happens. It’s not something that occurs too often but, yes, the head of the nipple can break off. Yours looks like it has some corrosion and/or debris on it, so it’s been like this for a while. Take a small crack or even manufacturing defect, add salt and time, and the brass can fail, especially since it is a stressed part by nature. Best way to deal with it is to say “Huh? That’s odd,” and replace it. Unless you deal with hundreds of wheels at your local co-op, you aren’t likely to see it again. If you do deal with hundreds of wheels at your local co-op, you aren’t likely to see more than 1 or 2 out of a thousand wheels.