I have a set of DT Swiss TK 7.1 (32 hole) rims, laced up with DT's to 105 hubs, and I've been noticing these hairline cracks at the eyelets. It's on every eyelet on the drive side of the rear wheel. The front wheel has it too, but the cracking isn't nearly as extensive , but it's on almost every hole, not just on the drive side.
To answer possible questions: I've been riding them almost exactly a year now (minus the winter, and some rides on another bike), while weighing between 190 and 200 lbs. My bike computer is showing about 3500 miles. My racing/serious training days are well behind me, so I don't do any sprinting at all these days, just steady paced exercise riding on hilly but very good, rural roads. The tires are some big, fluffy 700x32 Continentals, running about 75-80 psi, so I'd say the wheelset has got it about as easy as it gets.
I'm getting the impression the cracks are in what appears to be a thick clear coat finish, but I don't feel them at all when dragging a fingernail over them, so I'm concerned they may be underneath in the rim itself, or the surface anodising, but I really have no clue, and would appreciate any info, or even good guesses.
Thanks..........