Originally Posted by
Psimet2001
Indeed they stretch a lot. So do most spokes. That should really be taken care of during the build. Builders use all sorts of terms to describe that process. Sometimes incorrectly. We refer to it as "stress relieving" at our company but really you're stretching the spokes and forcing solid seats with the rim and hub and straight lines with the spokes to eliminate slop. I won't say you won't ever see a tension reduction with CX Rays after they have been professionally built but that stretch and drop should be minimal at most and is usually a factor of the rims or hub deforming.
The WH-R540 is pretty unique - that's the one with the lateral cross of upside down paired elbowed spokes with only a 16h rear, similar to the WH-7700 set pictured above, the only other wheelset like it. There are beefy oversized nipples at the hub, in nicely-aligned seats, and special aluminium rim inserts that fit tightly on the elbows, much snugger than any hub flange. The rims weigh 560g(!), so IMO there's very little going on in the way of bedding-in or deformation; at a guess I'd say it's easily >90% spoke elongation. I replaced the much beefier standard spokes one at a time, truing the wheels as I went, to maintain standard spoke tension.