CR List,
Clarifications on my question about the black Cinelli Stem Bolt. This is the bolt that holds the stem in the fork steering tube, not the one that clamps the handlebar, in case anyone was confused. It is definitely steel (magnetic) not some exotic metal, and it is black, not painted or anodized. Sort of a black oxide, maybe. Ripe for rust. It came in a Cinelli plastic envelope (winged C logo).
It happens I have a Cinelli 1A stem whose chromed steel bolt I can compare with this one. Both use a 6mm hex key, but the black bolt's head is checkered on the outside with a diamond cross-hatch pattern like you see on gun stocks. Also the head has marks stamped into it: B R U G O L A 12 . 9 on top, and GC on the side. The head diameter is larger at 12.8mm vs 11.85mm for the regular bolt. Similarly, the shank of the black bolt is larger at 7.9mm vs 6.95mm. The wedge nuts are of similar but not identical dimensions, although the threading is not the same, of course. The black bolt is maybe 5mm longer than the regular bolt. Each bolt has a pair of brass washers, which are all identical.
There are no great issues hanging on the identification of this bolt; it's just a curiosity. If anyone knows anything, I'd be glad to hear from you.
John Hurley
Austin, Texas, USA