nymtber

...and I wasn't even riding!

I was tensioning and truing my rear wheel to my MTB today, because this weekend I noticed that it had a slight wobble, enough to hit the brake pad. I wanted to alleviate this. I got it trued up and tensioned evenly, and decided I would go around the wheel grabbing parallel sets of spokes and making sure no undue stress was built up, when *PING* there goes a spoke. Broke at the j-bend.

Luckily, I have a pile of spokes (wheelsmith) from the wheel I tore apart and re-built a month ago, and one of the lengths was a perfect match! Got it replaced and trued back up, good as new.

My question: Should I be worried about more breaking? or was the spoke maybe just a weak one or something? This is not a wheel I would trash, its an LX rear hub and a Sun CR-18 rim, If there is reason to worry, I will re-build the wheel...I can steal the rear wheel (the one I recently built up) off my single speed if need be, and slap the cassette on...

The spokes in question appear to have an "N" in the head of the spoke...any clues as to who makes those?

sstorkel

I wouldn't think a spoke should break just from being grabbed... unless the tension was insanely high? Or the spokes are really old? If either of those apply, then I'd be worried about additional spokes breaking...

nymtber

Nope, actually I had to add tension to some of the spokes. They weren't dangerously low or anything but were a little lower than I usually have my wheels (I have a tension meter). The spokes/wheels are only 7 years old. I am going to believe it was a freak thing and the spoke itself was weak or deformed at the j-bend. Since these were machine built wheels, who knows how the spokes were treated.

sstorkel

If the tension had been too low for a long time, that can also contribute to spokes breaking. I probably wouldn't worry about it too much... unless you end up breaking more spokes in short order. Might not be a bad idea to carry a FiberFix kevlar repair spoke for the next few rides, though!

dscheidt

spokes break because of fatigue failure. The elbow is the usual place for this (which is why you should use double butted spokes when building wheels. machine builders use straight spokes because they're cheap, which is their sole advantage. the butted section helps prevent this). It doesn't take much under tension to get the spokes to fatigue pretty quickly, particularly if you're riding in rough stuff. I'd carry a spare....

spokes marked "N" are probably made by chun nan, of Taiwan. there products range from cheap junk (they still make galvanized spokes) to not-awful.

noglider 

It's not time to worry yet. If it happens a second time, it's time to scratch your head. If it happens a third time, it's time to replace all the spokes, all at once, because they are fatigued.

nymtber

Ok, I will just ride and if I break any, I will replace them. If they last, I will re-build both front and rear this winter...These wheels stay pretty true, but seem to loosen up sometimes. The rear wheel I built (that's on my SS bike) has so far survived all 6 miles or so I have put on the bike, with some rough sidewalk and railroad tracks under them, without so much as moving from where it was after I built it, using double butted spokes. I checked the front wheel today, nothing so far out of whack on that . I actually took the tire off the front wheel though and re-aligned the label with the valve stem...Looks more appealing to the eye now

I also re-adjusted the cup and cone bearings on my Sirrus today...WHY do they put them so friggen TIGHT from the factory? They weren't ratchety, but darn near it, now they are smooth as buttah! I almost think my average speed is going to go up, I will see tomorrow. Yes, they were that tight...

noglider 

If they loosen up, it means they're not tight enough. If they're not tight enough, that explains the breakage.

Tighten them before you ride again.

You put most of your weight on the rear wheel, so pay attention to that. Front wheels rarely give trouble.