Quoted message said:A few weeks ago I had a catastrophic failure on a rear rim after breaking one lousy spoke.
The rim was a 36 hole Araya 700c rim. Double wall and double eyelets. The wheel had less than 500
miles on it. I was using 14 straight gauge wheelsmith spokes. I weigh 250 pounds.
You don't mention what particular rim is was, or what wheel size. You don't mention whether this was
on- or off-road. The rim may have been too light for the application, but there's not enough data
here to tell.
Quoted message said:While coming down a steep curvy mountain grade ( I was using my brakes a lot ) , I popped a drive
side spoke (right side), and my wheel immediately tacoed and was trashed beyond repair.
The right side spokes are under twice the tension of those on the left. They are pulled so flat that
side loads apply large fluctuations in tension to these spokes. It's an inevitable side effect of
having 8, 9, or 10 speeds crammed into 130mm or 135mm rear spacing.
Were you staying centered over the bike, or hanging your body off to the inside or outside of the
turn? If you don't stay centered over the bike, you cause unnecessary side loads on the wheels.
Quoted message said:I can only suspect that I had built the wheel to tight.
That's not it. If the spoke broke at the elbow, then it was probably a faulty build, with
insufficient stress relieving. Oddly, breaking spokes is not a symptom of a too-tight build (usually
it's the opposite).
Quoted message said:The reason the spoke broke was from Chain Damage a few rides before when the chain jumped in
between the spokes and the cassette causing damage to all of my leading spokes.
If the spoke broke at the point of chain damage, then it may well have broken from an overload.
I have to observe that it's none too surprising if a 250 pounder honking down a mountain road,
side-loading a ridiculously dished rear wheel with chain-damaged spokes, were to suffer a spoke
failure. If this spoke were to fail while being side loaded, it's none too surprising if the same
force that broke the spoke were to bend the wheel beyond repairability.
Not all these conditions may apply in your particular case.
Things you can do in the future to prevent recurrences include:
Use a spoke protector Build a dishless rear wheel with an offset rim and low dish hub Tension the
drive side spokes to 100-120kgf Properly stress relieve your spokes with a momentary overload Use a
heavier rim Use butted spokes, 13/14ga or 14/15ga right, 14/15ga or 15/16ga left Don't side load
your wheels unnecessarily
Good luck addressing your problem.
Chalo Colina
