Originally Posted by
unworthy1
a rolled thread also (very slightly) increases the diameter of the final threaded portion compared to the original diameter of the stock (in this case a tube) since the process forces metal both UP (in the tread crests) and DOWN (in the thread roots). Not sure if that small difference would require slightly undersized steerer tubes (or lathe-turning them down) or if that could make crown fitting a problem and in either case if that could be a deal-killer.
Nope! Incredibly high precision high tensile strength parts can be roll threaded easier than threads cut. Aircraft spec Ti bolts are commonly rolled as are to the best of my knowledge ALL aircraft bolts. Cut threads introduce a stress riser at the thread/body join.
Steering tubes are quite different and I can't imagine why any company would invest in rolling threads on them when cutting machinery would produce perfectly satisfactory results at a way small fraction of the cost.