HI Brooks, I contacted Sunrace in USA and Netherlands, and they replied as follows: USA said: "Chain should be OK if it is fairly new and not stretched. Your local shop can check the wear of your chain and advise whether you need a replacement or not. The rear derailleur you need to know which model you have as there is only one model we have tested that works. That is the most recent Shimano RDM-6000GS Deore rear derailleur. SGS will not work." Netherlands didn't say much, just provided me with the following RD Compatibility chart: https://redirect.viglink.com/?format=go&jsonp=vglnk_155050337780314&key=6b590a383d5c8ad74c577b3652ca2031&libId=jsaho1tt010006wf000DA41o5y3ly&loc=https%3A%2F%2Fforums.mtbr.com%2Fdrivetrain-shifters-derailleurs-cranks%2Fsunrace-11-50-cassette-1041601-2.html&v=1&opt=true&out=https%3A%2F%2Fwww.ison-distribution.com%2Fuploads%2Fsunracecompatablitychart.jpg&ref=https%3A%2F%2Fwww.google.co.za%2F&title=Sunrace%2011-50%20cassette%20-%20Page%202-%20Mtbr.com&txt=https%3A%2F%2Fwww.ison-distribution.com%2Fup...blitychart.jpg I have the GS model, which seems to be compatible. PS. here ae links to pictures of the SGS and GS. Look at the differente shape of the housing where the clutch is located. That is how I identified mine to be a GS. https://bike.shimano.com/en-EU/product/component/deore-m6000/RD-M6000-SGS.html https://bike.shimano.com/en-EU/product/component/deore-m6000/RD-M6000-GS.html