Being faced with a similar problem, I'm curious whether anyone might have some feedback/wisdom to share (acerbic or otherwise) regarding the one potential solution that seems rather obvious to me, but that I've yet to see anyone mention in this or any other thread on this topic.
If I have a carbon fork with 1-1/8" aluminum steerer that I'd like to install in a carbon fiber frame that was designed for a 1" steerer fork, is there any reason why the aluminum steerer couldn't be turned down on a lathe to the 1" ISO spec? IOW, take the shaft from 28.6mm to 25.4mm, and the crown race seat from 30.1mm to 26.4" ?
Seems to me that taking roughly 2mm - 2.5mm off of the meat of the steerer shaft should still leave it well within the safety margin in terms of durability (though i don't have the specific fork in hand yet, so can't measure the ID of the shaft to be sure of the resultant wall thickness.) Obviously this would need to be done by a competent shop, with an eye kept on avoiding overheating of the shaft and affecting the aluminum/carbon bond. And careful attention to the surfaces and radius of the race seat and crown face.
Any other reasons to avoid this approach? (I understand that it's easier/simpler/cheaper to buy an appropriate fork, but in this case I'm highly motivated to use this particular fork if I can find any way to make it work. It's a 650c aero fork, not easy to source. I may fab some external adapters for 1-1/8" cups as a plan B if turning down the steerer is not a worthwhile approach. Unless anyone knows of a source for such adapters?
Many thanks for any thoughts/jeers/flames/musings/tributes to forebearers, etc.
