Originally Posted by
HillRider
Years ago when threadless steerers and headsets were first introduced, Shimano didn't make (and still doesn't make) any threadless headsets but their sponsored Pro teams wanted to use threadless forks. The team mechanics lathe turned the adjustable cups of Dura Ace headsets to remove the threads and allow their use on threadless steerers. It had to be done carefully to keep the race concentric and a very precise fit to the steerer tube but it apparently worked. This is not a job for a file used by hand.
That reminded me of something I read about Jobst Brandt's bike a few years ago:
bikecult.com > bikeworks nyc > archive bicycles > peter johnson road touring
I'm not quite sure I understand why the adjustable cup still needs to be a precise fit to the steerer tube, though -- I can see the problem if it were a tight fit and off-center, but I'd think that if it had enough clearance, it could self-center while adjusting the headset bearings, and then it would hold that position after the stem clamp bolts were tightened.
But threadless headsets aren't in my wheelhouse.
