Help with thread form on Simplex Rear Derailleur

[VeloFellow54]

Re:

Depends what you want to do. I would have thought that finding a bolt with the correct thread should be relatively easy. Alternatively find a slightly larger (known thread) one and drill/tap to the new thread.

 

[VeloFellow54]

Might be a bit late but I have just acquired a huge Pile of spares for 50's Simplex Tour De France mechanisms. Probably have want you want NOS. Let me know if you are still looking