Suntour Cyclone rear Derailleur adjustment question
 

Hi all,
I have an early model Suntour Cyclone just like the one shown here http://www.yellowjersey.org/cyclone.html It's the regular one on top, not the GT.
It has a single bolt that fixes it to the frame which can rotate freely forward and backward to the the built in stops. It's labeled as parts 1 and 2 there, the upper non-sprung point. Even with the bolt fastened tight it still rotates so I assume it is supposed to move, but is not sprung like newer derailleurs I have seen. I have the washer and parts just as in the diagram.
SO, my question is, how should this be adjusted? It seems to stay where I put it through several hours of riding but why does it move so easily? Should it be forward to get the most chain wrap or back to some degree for some reason?
Thank you!

These adjust the same way Campagnolo derailleurs did until 2001. The Chain tension pulls the RD forward against the stop and it sits at a constant angle. The only movement to take up chain slack is idler cage rotation.

Use the "B" (9 in the diagram) to set the derailleur to stay as close to the sprockets without ever touching one through the chain.

Make sure to test he setting with all the sprockets and both chainrings. One nice feature of this design is the RD pantograph doesn't move making the adjustment easier to set and verify.

Unique
 

Hi - This is years later, but a big thank you for the only account I could find on the net of how to adjust this derailleur - I was v puzzled by having no barrel adjuster - so thanks again.

Understood. With a friction lever controlled der there is no need (at least for function) of coordinating lever movement with der position WRT the cog set. So ne cable adjuster is needed. Unlike an indexed system where a specific lever travel (cable movement) equates to a der movement that matches the cog to cog spacing. For about 60 years this non indexed system aspect did just fine.

I highly recommend The Dancing Chain by Frank Berto if one wants to better understand the multi gear system. Having some sense of history makes for better current time decisions. Andy