Recently damaged the rear derailleur on my old city bike - the derailleur is a Shimano integrated 6-7 SIS Max 28t - which is no longer manufactured. I can get a used replacement via ebay but was wondering whether something like a 6/7 speed tourney RD-TY500 would also work. Any thoughts?
Do have the RD in your workshop? You should just give it a try. It might very well work, all Shimano 6/7 speed derailleurs have the same pull ratio. (May be able to fit it without breaking the chain.)– CarelOct 9, 2018 at 14:38
1Looks like you’ve removed the derailleur hanger (silver) as well as the derailleur itself (black). If it wasn’t damaged and was taken off in error, it’ll need to go back on before any new derailleur– SwiftyOct 9, 2018 at 16:35
What's wrong with that derailleur? Is it bent or worn/sloppy ?– Criggie ♦Oct 12, 2018 at 6:59
Any 6/7 speed Tourney derailleur will be compatible with your shifter, i.e., it will index on a sprocket correctly for each shifter click.
Whatever Tourney model you get you want to make sure it can handle the largest rear sprocket you have and the total capacity which is the difference of tooth counts between smallest and largest sprockets plus difference of tooth counts between smallest and largest chainrings. Longer cage derailleurs have larger total capacity because they can take up more chain slack.
Specs on the RD-TY500 SGS are here.