Originally Posted by
cyccommute
First, if your spokes are breaking at the nipple, the problem is that the spokes are too short. I’ve been seeing this problem on a number of bikes with OEM wheels, especially if the wheels have aluminum nipples. They aren’t making the wheels with the proper spoke length so the threads aren’t buried in the nipple. They only go down about 1/2 way. That stresses the spoke at the nipple and makes it prone to breakage. Adjusting the tension won’t fix anything. The only thing to fix the problem is to rebuild the wheel with the proper spokes.
Yes, the thread valleys make nice stress risers. The threads are rolled into the spokes and I'll bet they have all broken right at the point where the first thread reaches full depth