... bicycle handle bar nuts fit the 7x bore.
I just tapped one to fit some 1/8" threaded tube used for lamps (straight 1/8" x 27 pipe), bored the other out with some slop to allow it to move up the wedge.
Welded a 1/4 x20 coupler to one end and used a pipe nut (modded to straight 1/8" x27 thread) as a jam nut. The plastic 1/4x20 wingnut sets the depth stop. The aluminum spacer gets it thru the change gear door (I have a hinged door on mine with a captive thumb screw so it's a bit longer..)
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