Originally Posted by
Viich
Hey guys. I've got a wheel on a bike I support (family member) that has broken 2 spokes in 2 weeks. After the first one, I happened to have a spare of the right length so put the spare spoke in and trued the wheel.
Both spokes the head snapped off and the spoke pulled through the hub. Both drive side head-out trailing spokes.
This is the OEM wheel on a Raleigh USA Merit road bike. (Rim brake) It's about 5 years old, hasn't seen excessively high mileage, though the rider is a little on the clyde side, and recently been training a lot more, developing more power and fitness.
Yours is a fairly common problem. It’s related to spoke tension but it is also caused by other factors. Straight gauge spokes (one diameter from the head to threads) are more prone to the problem because they aren’t as elastic as butted spokes. Heavier riders and/or people carrying heavier loads stress the spokes more and are thus more prone to breakage. That’s because the load puts more stress on the spoke but also because the load causes the rim to deflect more when it is at the contact patch which cause the spokes to loosen more than with a lighter rider. The head of the spoke is detension/retensioned constantly. It’s something like constantly bending a paper clip, eventually it is going to fatigue and break.
What can I do to get the wheel reliable again? Any suggestions?
With these spokes? Probably not. For the best wheel, rebuild with stronger spokes like DT Alpine III or other triple butted spokes. The heads are thicker by 0.3mm which increases their strength by about 50%. Additionally, the larger sized spoke bend means that the spoke fits tighter in the hub so that it move less during the detension/retensioning process which is going to occur no matter what you do.
That strength comes at the price of only a slight increase in weight …about 7g per wheel. The spokes are more expensive but cheaper than several wheels you’d replace with lighter spokes.