I have an old Campagnolo Gran Sport rear derailleur. It is chrome plated bronze. I know almost nothing about these, but my sense is that they developed very rapidly in the 50s, sometimes changing within a single year. Is there a resource for understanding the evolution of these derailleurs? I found John Siemsen's Pave album in Wool Jersey, but that doesn't document the history of the derailleurs.
Best regards,,
Marcus Helman
Huntington Woods, MI