Originally Posted by
johnny_cycles
Thanks for the reply. Seems like M1.0x10 is the hanger threading set forth by Campy and adopted as the industry standard. And what my Nuovo Record derailleur is as measured.
Modern Campagnolo derailleurs are 10 x 1mm thread. Nuovo Record is 10mm x 26tpi, just different enough to make a bit of struggle mounting on a non-Campagnolo hanger.
So then the Suntour hanger, which is a common hanger, should be in the standard set forth by Campagnolo. Yet they seem to differ in their nominal diameter.
Not sure how to explain the diameter discrepancy. The advice above to run a 10 x 1 tap through the hanger may be enough. It'll still be a bit tight, but t can work. The threads on both the hanger and the mounting bolt will be slightly re-formed, but still adequate. Millions of people have done this to mount Campagnolo derailleurs on non-Campagnolo dropouts.