Ming the Merciless
There is no mercy
- Location
- Inside my skull
Maybe it lost its temper after so long being neglected?
Why do my spokes keep breaking? - Bike wheel science.
- Thread starter united4ever
- Start date
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Maybe it lost its temper after so long being neglected?
Ian H
Ancient randonneur
Temper fugit.
Punkawallah
Veteran
"Explosive tension". Could happen at any time - lucky you weren't anywhere near it :-)
Yellow Saddle
Guru
- Location
- Loch side.
That's an interesting question, but before the speculation fest starts, are you sure the spoke broke whilst haning there and that it did not break before it was hung up and you just noticed now?
simonali
Legendary Member
Was definitely not broken before the wheels were retired. Only really keeping them as they are the ones that came on the bike, in case I ever sell it and the new owner wants them.
Yellow Saddle
Guru
- Location
- Loch side.
OK then. Back in the day when I had a wheelbuilding and wheel repair factory, I experienced the same. A sproke broke on a wheel waiting for repair. We all heard it and knowing what it sounds like, knew what it was. It was only found when that wheel's turn on the operating table came.
Spakes break from fatigue and the mode is a travelling stress crack. The crack starts on the outside of the spoke bend and slowly works its way inwards. At some point, the tension in the spoke is too much for the remaining material ahead of the crack and then the crack speeds up. The difference in speed can be seen when you inspect the spoke's broken end with a hand lens. You can see old exposure and new exposure quite clearly.
There is a very, very small change in spoke tension when temperature changes and my guess is that your broken spoke was at the very limit of holding on, the temperature changed (probably increased if we're talking aluminium rims here) and that last straw broke the camel's back.
An aluminium 700c rim will expand in circumference by about 0.5mm if the temperature increases by 10 degrees C.
You can fill in the gaps by figuring out what the conditions were when your spoke broke.
Likely not reached the same point in the fatigue life of the spokes.
rogerzilla
Legendary Member
The unkeyed and annoyingly expensive Campag seat clamp bolts used on some vintage bikes can also snap when the bike is just standing around. Like spokes, they're steel and under constant tension. However, they're also chromed and this doesn't help their life expectancy at all. Chromed spokes had a bad reputation.
sevenfourate
Devotee of OCD
- Location
- Lowestoft, Suffolk
Right.
Bjorn Borg apparently used to use very high string tension on his Tennis Rackets. This; in the day of Wooden frames.
Supposedly strings / frames would regularly 'give up the ghost' / explode / snap. Often when not in use.......
