Bruce Graham said:I had one let go without any jam that I was aware of. I did notice that
the rim had yielded around the socket a bit and the nipple did not want
to line up exactly straight with the replacement spoke, so that may have
added a cyclic bending force to the threaded end of the spoke.I should add that quite a few of the sockets had moved a bit in the rim,
due to much loaded touring over rough roads of various types and probably
a bit much spoke tension.All my other spoke failures have been at the bent end.
You can get the same problem with too many crossings, especially with a
large-flange hub.
The usual 3x may be too much for a really big hub. If you look at the
two spokes either side of the valve, these will generally be the width
of the flange apart at the hub end when using 3x. With a s/f hub this
is very similar to the distance between rim holes, so the "valve" spokes
are parallel. With a l/f hub the spokes converge on the rim and aren't
perpendicular.
Normally the nipples can orient themselves in the rim to some extent
(Sapim nipples have rounded heads to make this easier) but if they
don't, the spoke has to bend.