Originally Posted by
Odlorah
The FS has a flat hook hat holds the old Simplex. Unfortunately it doesn't fit with the Suntour. Could I just go to the bike shop and ask for one? Is that something that is fairly common?
That hook is called a derailleur claw. Simplex likely used different threads from the rest of the world, even on their claws. Most of the time that doesn't matter to anyone because you don't usually take the claw off of a derailleur, which means you never have to swap them.
In any case, you can buy a claw for about $4 at just about any bike shop. But take the Suntour Superbe with you and see how it mounts on the claw. Normally a derailleur wouldn't have used one because it would have been used on a bike on which the dropout had an integrated derailleur hanger. The threads are pretty much universal (except for Simplex), but the length of shaft and how tightly it fits to the claw and whether it needs a shim etc. might make it not a simple plug&play. I've never used a Superbe Rd but I imagine it is what Suntour called the slant parallelogram type. The Simplex would have a spring-loaded pivot at the claw and another on the pulley cage. The slant parallelogram type did not pivot at the mount. It was meant to sit at a fixed angle to the frame, and it generally had a stop screw to adjust its position. So the claw mount doesn't have to be free to swing forward and back but you have to be able to push it forward against its stop.