Cyclist0383

I've ridden for many years and have never broken a spoke. In the last three weeks I've broken four. What gives? I can't figure out why.

The wheel:
Formula fixed gear hub (32H high-flange) laced with DB Sapim Race spokes to a Mavic Open Pro rim. 700x28 Conti Gator Skin tires. Built by a pro mechanic who has been building track wheels since the 1960s. The wheel has been re-tensioned twice.

The Rider:
Eighty kilos and a lock and pannier. About 90kg (198lbs) total.

The streets:
Some cobblestones, but the spokes have tended to break while riding at around 35kph on nice, new roads.

Last summer I rode on 28H fixed wheels on the same streets with smaller tires and had absolutely no problems. Those wheels are still true as the day they were built.

Does anyone have any ideas what could be causing all this spoke breakage? Thanks.

HillRider

Where exactly did the spokes break? If it was at the elbow or at the threads the likely cause is fatique. If they broke somewhere in between, it's likely something physically damage the spokes. Did you catch something in the wheel like a stick or piece of wire?

Cyclist0383

They are breaking about four or five cm from the elbow. Nothing was caught in the spokes. This is a new wheel with under 2000km on it.

AkAk2000

Look closely at the spokes on the wheel where the spokes are breaking. Do you see little bands of discoloration, or rust? It will look like 1 mm stripes or something, even dirt.

If you see this, you probably got bad spokes in the bad wheel(s). I think the alloy is bad. There are batches of bad spokes that get made with out of spec stainless alloy. This happened to me, and I had to rebuild my wheel with new spokes. One wheel of the set had bad spokes (all of them), the other was fine.

Cyclist0383

No problem with the spokes. I'm using spokes that came out of a bag of 500, and the National Team is using spokes from the same batch. There have been no other reports of mass spoke breakage.

HillRider

One more question; were the broken spokes adjacent to each other or randomly spaced around the rim? From where they are breaking it really sounds like mechanical damage, not fatigue.

Cyclist0383

Thanks for the thoughts, this one is really a head scratcher, both for me and the mechanic I go to.

The are breaking in a random pattern, both drive side and non-drive side. They has been no mechanical damage, that I would have certainly noticed.

ib4it

I had 2 break recently (first 2 in my life) at random on the non-drive side rear wheel, while riding on a smooth straight road. I replaced them and everything is OK now (about 500 miles later). The mystery will never be solved.

geo8rge

If you road the bike with broken spokes for a long period of time, the spokes that did not break where subjected to much more stress than normal. So they might have been weakened. When one goes it is like dominoes falling. The rim also might no longer be flexing under load properly. You might be better off with all new spokes and maybe a new rim.

Cyclist0383

I didn't ride for a long time with broken spokes, a kilometer at most. That's why it's so perplexing.

I'm thinking about re-spoking the wheel with 14 gage spokes, which was suggested to me by Tony at IRO where I bought the hub. Good egg, that Tony.

EvilV

This happened to me and it isn't always immediately obvious that a spoke has snapped. I started hearing a rhythmic click and rode on for maybe forty miles to finish the ride. Then on closer examination at home, I spotted a spoke snapped just inside the nipple. I replaced that, but within another hundred miles, four more spokes went too. Since then, I've had no more trouble. Once there's a broken spoke, others get fatigued by the unusual flexing of the wheel and they break later.

Kotts

Is there any chance that you're getting "fretting wear" where the spokes cross? If you've been riding this wheel for that long, it's quite possible. It wouldn't take much of a notch to create a stress riser. Take out a "good" spoke and look at/feel it closely.

mike-on-da-bike

heat streched them?maybe you ate too much xmas pudding this year

graywolf

It is not clear from the OP if the wheel is new build, or just retensioned and trued.

Old spokes can be near their fatigue limit, or already stretched to the tensile limit

With new spokes it is usually a slightly loose spoke caused either by being twisted and untwisting as you ride, or the nipple unscrewing (assuming they were all properly tensioned to start with). This causes the spoke to be slightly longer than its neighbors and thus it flexes at the weight comes on and off it.

Spokes loosening can also be caused by mismatched nipples, not necessarily the wrong size either sometimes they are just slightly out of tolerance and unthread easily.

On the other hand you might just have gotten a batch of defective spokes.

operator

Bad build or a somewhat unlucky pick of spokes - why did they need to be retensioned twice already? Good wheelbuilds don't **** up out of the stand.

Cyclist0383

Because I kept on breaking spokes and asked for them to be retensioned just in case, as neither the guy who built the wheel (pro team mechanic) or I could figure out why spokes kept on breaking.

I had the spokes on the rear changed out months ago and have had no problems since with that wheel, although I did break a spoke in the front (WTF?) while just riding along the other day. It broke in the *exact* same place as all the spokes in the rear, leading me to believe that it was a bad batch of spokes from the factory.

Bob Dopolina 

1. Karma.

2. You were long overdue.

Cyclist0383

Jaa, when it rains it pours. After many years of one flat a year I was getting several a week last month. I even changed the tires on my winter bike, pumped them up, and put the bike in the garage. A few days later both tires were flat without ever riding the bike.

I was also pulled over while driving twice within two minutes yesterday in newly minted speed traps on the highway. Urgh.

Bob Dopolina 

Jeez. You'd better lay low until this blows over. Stay away from sharp things and tall buildings!