I got a custom TI bike 11 years ago, designed for the Rohloff (sliding dropouts). Last week the seat stay cracked in two (so much for TI lasting a lifetime!!!). It was built be Merlin, which has changed hands, so no more "lifetime warantee." They offered me 50% off a new frame, which I may do. But my Rohloff is the rim brake version, and nearly all of their frames are disc. (Would like to go with a "gravel" type frame, mainly due to the shorter reach/top tubes -- my torso is 10cm shorter than normal compared to my legs, hence the custom frame.) Rather than going with their one rim frame -- then needing a chain tensioner and torque arm -- perhaps there is a gravel type frame that has sliding dropouts? (I have a Surley "single speed" hardtail MTB like that, which I put a Rohloff on.) I though I read an article not long ago about such a frame.