gaucho777 

A colleague of mine inherited a very nice Nishiki from his father. It's actually one of the nicest Nishiki's I have ever seen, a mid-70s black & red Nishiki with full Campagnolo Nuovo Record and a factory milled Cinelli stem (~'77 Nishiki Pro?) and an elegantly sloped fork crown. Overall, it's in good shape. I've helped with a few minor repairs to get it back on the road. However, he's been breaking spokes at an unusual rate. Over the past couple months, he's broken three spokes, all on the front wheel. But what's most surprising is that the spokes have been breaking in the middle, not at the elbows as is most common. One spoke broke where it intersected another spoke, but two others broke right in the middle of the spoke. The wheels are 36h and have even spoke tension; maybe a touch tight, but not exceptionally tight according to my own unscientific assessment. Lastly, worth mentioning is that the spokes are fairly thin, butted Stellas (at least they have a star on the head)--guessing 2.0/1.7/2.0. Any reasons why these spokes are failing in the middle? The only explanation I can think of is that maybe the spokes have experienced a high amount of wind up/twisting during the initial build or during subsequent maintenance/truing. The spoke nipples do feel tight. Any other potential causes for multiple "mid-spoke" failures? When would it make sense to simply rebuild the wheel (Campagnolo NR hubs and classic Rigida clincher rims) rather than continue to deal with broken spokes. Thoughts?

Velocivixen

Don't know. My wheelbuilder told me that a frequent cause of spoke breakage is too loose vs too tight, so if they're breaking & a little on the tight side not sure that would be the reason.

USAZorro

Are the spoke holes drilled in the rim down the middle or offset? If offset, are the spokes laced so they cross the centerline of the rim?

gugie 

It's very rare for spokes to break in the middle. I would think there was some sort of damage induced during the butting process. The fact that it's a front wheel leads me to believe there may have been some damage to the spokes while riding.

At any rate, after 2 broken spokes, I'd consider rebuilding. Three is automatic for me.

Rebuild.

Lascauxcaveman 

I've broken them at the elbow (twice) and where two spokes cross each other (twice). We're talking 30-year-old, brittle galvanized spokes, though. I've never broken a spoke on a front wheel.

FBinNY 

Spokes breaking anyplace other than the elbow or threads means that something is happening other than normal wear and tear.

The most common cause is "notch failure" where there's a nick or gouge in the spoke which acts as a stress riser and leads to a failure there. We see this most often on right side rear spokes, which are damaged when the chain overshifts into them.

The other fairly common cause is "chloride corrosion". (here's more on that subject)This is a common cause of failure in certain types of stainless steels, and in spokes might be the result of the wrong grade of stainless, or improper processing. Sometimes impurities left over from the manufacturing process become gateways for chloride ions (ie. from road salt) to migrate into the steel where they cause the steel to become extremely brittle. The best evidence of chloride intrusion is tiny black dots or veins elsewhere in the spoke. When you see these, try flexing the spoke by squeezing opposite pairs together.

Regardless of the actual cause, or whether you ever find one, multiple unexplained failures argue for a total rebuild, especially if the time interval between failures is shortening.

old's'cool

This could certainly be a contributing, if not primary cause. Stress risers, due to spoke-to-spoke contact, or some kind of systematic damage (including corrosion) to that particular batch of spokes, are another potential cause. The fact that the spokes are butted would tend to focus corrosion related failures in the butted region, due to the higher unit stress (though the elbow is certainly a vulnerable area also).
I concur, after 2 or more failures, time to relace, or at least address the issue, e.g. uneven or insufficient tension.

Michael Angelo 

Cheap low end spokes. See that a lot on dept store bikes.

gaucho777 

Thanks for all the feedback, especially [MENTION=158672]FBinNY[/MENTION] for the interesting notes on chloride corrosion. It is a curious case. These are nice quality spokes which didn't appear to show any significant signs of corrosion, but I'll have another look for black dots/veins when I have the chance.

Robofunc

I had the chlorine corrosion issue on an otherwise nice wheelset. Tiny black spots on the spokes. The spots go into the spoke and can eventually cause it to break. Rebuilding with fresh spokes is really the only way to save the wheels.

plonz 

Just out of curiosity, are the rims Rigida AL1320s by any chance? Reason I ask is I just laced up a pair to Campy NR hubs and they turned out great. I can send you my spoke specs if you decide to rebuild.

rhm

Interesting explanations! Even accepting chloride corrosion, though, wouldn't they be more likely to break at the ends, like other spokes?

But whatever. There comes a time when you need to replace the spokes. Now is that time.

mparker326

I have a front wheel that this is happening on as well. I used cheap Sapim spokes for the build. I read they had an issue with this occurring in a batch of spokes they produced. My spokes have a small spot right in the middle of the spoke where they break. I haven't rebuilt yet, but I have replaced quite a few spokes. I hate having to spend a couple hours to build a wheel even though I know it is inevitable.

fender1

Spokes breaking in a 38 year old wheel, with an unknown build/use history.....seems pretty clear that a rebuild is in order.

Ex Pres 

I had a random spoke break in the middle earlier this year. Good, not cheap spokes. I took a close look at the break point and could see a void right in the middle of the spoke. Cause? I'm not sure, but appeared to be in the manufacturing process, not corrosion - no discolorations, not at the cross, no apparent gouges.

FBinNY 

No. Chlorine ion embrittlement is a pretty random event. Some years back, 2 pairs of wheels that I kept in Cozumel suffered from this cancer. The spokes broke in random places while in storage, and all four wheels looked like victims of vandalism.

On close examination, I saw the characteristic black dots and veins at various places along the spokes' lengths. When I cut the wheel apart, I found that affected areas were as ductile as dried spaghetti and would snap cleanly at the least provocation.

On a butted spoke, you'd expect more breakage mid spoke, simply because that's a thinner area. However I suspect that the elbows are protected by virtue of oil weepage from the hubs which tends to cover the spokes there.

79pmooney

If those are the old SS Robergel spokes, they are famous for breaking from fatigue. That they are breaking in the middle is a bit odd, but that they are breaking isn't at all. Figure those spokes dead and go out and get new ones.

I read the rest of the posts. This probably isn't fatigue, but using an incorrect SS wouldn't surprise me at all. SS for spokes was pretty new in 1977. Pre DT and Wheelsmith. (The ugly zinc plated Robergel Sports were radically higher quality spokes when it came to longevity and reliability. I raced the Sports and after one miserable wheel, refused to ever build with the Tois Etoiles (sp) again.)

Ben

Bikedued

This came up a few times at the shop in Lake Charles, but in the cases in Southwest Louisiana, road salt is not a concern. Storage in a shed with pool chemicals and/or fertilizer will cause strange things to happen however. We had a customer come in with a 5-6 year old Trek Navigator, they aired it up after sitting in a shed for a few years, and multiple spokes broke in the middle the first time someone sat on the bike to ride it. Like ten or more per wheel which could be catastrophic if the bike got up to even a cruising the neighborhood speed before failure occurred. We did warn customers buying new bikes not to store them in an unventilated area with said chemicals, but you never know what information is actually retained when someone is buying a new bike. The excitement factor sometimes negates important information.,,,,BD

Bikedued

And yes, the spokes had the strength of angel hair pasta. It was freaky!,,,,BD