Wow you are quick here! Thanks Maddog. They looked through the stock for 5 minutes for me while I was watching and said my gear was antique because it missed some "mounting hole that all new Shimano gears use".

So I guess I can use the "Tourney RD-TY500-SGS" without any adapter needed then? It is not expensive so I would just get one and try except for that it has to be imported from the US.. And on Shimano's site there are no 7-gear rear derailleurs.

Looking for 7-gear "hanger mount" real derailleurs I find Shimano Tourney RD-TY300, and also Tourney RD-TX35, would those work?

• bikester.se/shimano-tourney-rd-ty300-bakvaexel-med-adapter-svart-488560.html
• staffanstorpscykel.se/bak-vaxlar/1547-bakvaxel-tourney-tx-30-for-6-7-del-med-fastora-shimano-4524667432562.html

I do know how to adjust chain length. This one is mounted by a shop though and has worked for many years and both gears are in mid position so I wouldn't think gear is stretched much in pic. Weird angle is due to chain jumping out of cogwheels since teeth broken I think. By pulley I guess you mean cogwheel? Shop said cogwheels can't be bought, that entire gear is exchanged, and sounds reasonable since gear costs less that the cost of time to do the job.

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