its all anecdota I suppose; but reputations are made with difficulty and can be lost in an instant.
The worst QA problems I have found with DT spokes (hundreds of boxes used, all from the Swiss factory) are
- inconsistent butt lengths from box to box
- poor finishing on the swaged (thinnest) section
- stupid J-bend lengths in 14g spoke ends (for which you have the American importer to blame; this length became the standard for everyone else too, for a while)
- I once (and only once) found a single unthreaded spoke in a box of DT spokes.
In Sapim spokes (from the Belgian factory) the quality of the spokes in any one box looks excellent, and butt lengths are more consistent than in DT spokes. The butts are often shorter too so Sapim spokes usually work out a bit lighter (gauge for gauge) than DT ones. I worry that the Sapim logo (which is stamped next to the J bend) might weaken the spoke but I have never seen a spoke break there even when it has been gouged by the chain. I have seen a few nipples in Sapim bags which were 'blind' i.e. not drilled and tapped. I've used dozens of boxes myself and locally to me a good wheelbuilder uses Sapim and almost nothing else. He's used many hundreds of boxes and has very little bad to say about these spokes. I'm very interested to get to the bottom of the 'brittle spoke' instance I mentioned earlier.
The only comment I would make is that if you are in the habit of using standard weight DB spokes, and cut and thread them to fit, you need to keep more different lengths in Sapim than in DT; the short butts in Sapim mean that they can't be shortened by more than 5 or 10mm, whereas the longer butts in DT allow them to be shortened by more if necessary.
I've built least with ACI spokes and the butted ones are stronger than you might think in the skinny part because this is work-hardened. Even so they don't seem as hard (strong) as DT or Sapim. They are easier to 'set' and stress relieve though. The 'bad elbow' spokes I mentioned above were (I estimate) made about ten years ago. In recent years I have also seen black finished ACI spokes (in factory wheels) that went rusty, so maybe they make 'budget' spokes for bike factories in less corrosion resistant materials.
In addition to the wheels I have built myself I've had many wheels pass through my hands from a lot of builders/sources. If you get a wheel which is breaking spokes this is most commonly caused by the wheel not being stress-relieved. It can also be caused by the spokes being a bad fit in the hub, or kinked near the rim, amongst other things. In wheels where the stress relief isn't adequate, the spokes usually break at the J bend. However they can also break by the heads fatiguing and popping off instead. Modern wheelbuilding machines can be set up to stress-relieve the wheel but (for whatever reason, maybe the people running the machines don't understand the importance of it..?) the stress relief in most factory wheels isn't anywhere near adequate. Thus I recommend that any factory wheels (from big brand bikes) are best stress relieved (and the hubs properly serviced) when the wheels are new if you want to get the best out of them.
The situation is now complicated by the fact that both DT and Sapim have, in recent years, set up spoke-making factories in many other places. These spokes appear on factory wheels from Taiwan etc and are often indistinguishable from european made spokes. However they may not be of the same quality and indeed it is not clear to me that they use steel from the same sources as they always used to. So if you buy a box of Sapim or DT and they were made in europe, it is status quo; however if they come from a satellite factory it is not so clear that they will definitely be of identical quality. Currently if you buy DT or Sapim spokes in the UK via the usual channels you will get european-made spokes, but I don't exclude the possiblity that spokes from the satellite factories are 'leaking' into the retail market by various means.
cheers
