So I've been brewing up some ideas about a more elegant solution to running a modern stem on a threaded fork.
The solutions out there today seem needlessly clunky and make it difficult to get proper slammage etc.
This is my idea:
Essentially it's an oversized locknut. I have about 12mm of thread left over on my fork and could have more if I sourced a headset with lower stack height.
It would replace the locknut, thereby securing and tightening the headset just like normal, but would leave a 1 1/8" column on which to attach a modern stem. The M6 thread is to make it easy to install a topcap for the sake of completion. It would allow you to run the stem flush with the top bearing race. Wouldn't look perfect as it's usually hexagonal, but better than what's out there today.
One could also imagine a solution for a threadless headset where the adapter is cut into two parts. Say 3mm of the threaded part is cut off and threaded onto the fork, the other part is then threaded against it to lock and tighten the headset. This would allow you to run a threadless stem on a 1" threaded fork that is cut too short to do it the conventional way.
Weight? ~30g To be compared with a traditional quill adapter which weighs at least 150g.
Been trying to find a workshop to manufacture a prototype or two. So far no luck (for reasonable money). Since no one has the appropriate tool for the thread, it's down to finding someone with tools small enough to make an internal thread of that diameter on a lathe and it's proving difficult. Though so far I've only been calling local workshops.