It gave some extra years to my commuter-tourer-mtb aluminum bike. After a lot of abbuse, one of the rack mounts went stripped, and these adapters saved the day. It is actually firmer than mounting the rack directly to the frame in my opinion, as it is flat and it is made of steel. I don't know if it scratches the paint, but I would not care, as my intention is to leave it permanently. Unless it was a carbon frame that could be structurally damaged. No signs of rust yet (4 years), and not only for Tubus racks, of course.