Spokes Spontaneously Breaking

This is very bizarre. Riding on Sunday, I hear a "ping", stop and find one of my rear spokes has broken...and in the center. Figure I'll get it fixed the next day. So next morning I'm riding and, again, "ping" another rear spoke popped. This one broke closer to the hub end. I brought it to the LBS and they replaced the 2 spokes and trued it for $25. Mind you, the bike isn't very old and the spokes don't appear corroded (I don't beat on my bikes). The bike is a Bianchi which I only ride on pavement. I've had some bikes for 20 years and never popped a spoke, not even my MTB! So, 2 new spokes, wheel trued, I'm doing a 25 mile ride today when at around 10 miles, "ping"; then on my way home, another one (both back wheel, again). WTF! Two questions, any idea what would cause this? All broken spokes have been on the freewheel side of the rear wheel. Also, I only weigh 170 lbs., so weight isn't the issue. The only recent change (can't imagine it would have any effect) is new tires, which take considerably more pressure than the old. Second, should I rebuild the wheel (all new spokes) and approximately what should that cost. I'm thinking a new wheel might be cheaper, but there's nothing wrong with the current rim and hub. TIA.

It sounds as if the spokes have developed uneven tension. The wheel probably needs to be retensioned.

__________________
"All that we see and seem is but a dream, within a dream..."

not surprising that after one spoke broke another failed, they are of the same batch, age, stesses etc. if there is a spoke out and another fails later on that ride that is common also due to uneven tension/load... and freewheel side spokes are the usual suspects when spokes start beaking.

if you rode any significant distances with the broken spokes (without truing the wheel) and it is costing you money to get the spokes replaced it may soon be ost effective to have all spokes replaced on that wheel. they are all of the same age and 'quality' and may not be up to the task any longer/much longer...


all's'miles

curby

You may have faulty spokes. About 3 years ago a big batch of bad steel got made into OEM spokes that ended up an all sorts of bikes. They corrode and snap. Get your LBS to check em, but you can tell if they are corroding pretty easily.

Any idea what would be a reasonable cost for new spokes & truing? LBS already replaced 2 of the 36.

Broken spokes are from a couple of causes. Rim is deformed, bent and the spokes at that place tension is low, riding flexes spoke, they break. Think of bending a metal coat hanger back-forth, back-forth. The other is a poorly built, undertensioned wheel, same result.

The issue is the rim, not the spokes. Undertensioned wheel, deformed rim, erratic tension, broken spokes. Replace the RIM, new spokes, and have a competent wheelbuilder do it.

I believe that the rims are fine. When I acquired the bike from a friend it had hardly been used - probably under 20 miles. The rims (and the rest of the bike) were in pristine condition. In the last few months I've probably put on 1200 miles, but only ridden on paved bike paths. Both wheels were perfectly true until my rear spokes began to self destruct. Another question - What is retensioning and when (or why) would it be necessary?

I'm with Peter on this one. Don't waste your money having your old rims rebuilt. Find a competent builder, start with new high-quality rims and spokes, and ride happy.

I also agree, don't rebuild a wheel with a damaged rim. Your LBS should be able to tell you if the rim has suffered any damage.

a new cheap wheel may not be any better than what you are riding and may experience a similar life cycle. if the old hub is good quality then rebuilding on that with a good quality rim may be a good option, it can sometimes be difficult to find a single rear high quality replacement wheel (rather than a wheelset).

good luck

I broke 2 spokes on my Zipp 404 when the chain fell off into the hub due to poor derailluer adjustment - the stop wasn't adjusted. So maybe your chain is hitting / pulling the spoke to break, - check your derailleur stop adjustments.

For sure it could be the spokes. It could be a flaw in the material or damage.

Wheels were probably undetensioned to start with, now the rim is deformed, the tension is weird, breaking spokes. You can have a good wheelbuilder take the tension down to zero and essentially rebuild it ensuring the tension is as even as possible along with roundness and trueness, dish but the rim is still 'bent'.

If you are really worried about the rim, unlace the wheel and lay the rim on a perfectly flat surface to check it for trueness (this will not check roundness). If it were me, being a cheapskate, and given that I own a jig and a tensiometer, and have spare wheels to use anyway, I would still loosen all the spokes to the point that the thread was just showing all around, and then retension as if I were building a new wheel. I would then stress-relieve it, check it again for trueness and roundness, and try using it.

__________________
"All that we see and seem is but a dream, within a dream..."

This is how it should have been done.

When one spoke breaks the tension is transferred to the other spokes thus putting more tension on them. It's a chain reaction and the other spokes will fail more quicker.

A bent rim can be trued by adjusting the spokes but there is a limit. Better to un-tension all the spokes and then see how bad the rim is. Get the rim as true as possible by other means and then tension all the spokes while maintaining absolute trueness.