Originally Posted by
Bingod
its the M772 shadow.
chainrings are 50, 39 26 (stock was 50, 39, 30)
Chain is the original size stock size
re hanger alignment - its a new hanger - I'm not sure how to align it past fitting in place
quick edit: i did take the bike to the LBS who fiddled with it for some time. They did not improve on what I had done - but found no issue with the RD, but vaguely suggested this problem could be a compatibility issue
Part of your problem may be the chain wrap capacity. between your two cassettes and that wide range crank, you need a (50-26)+(36-11) =
49t capacity. The long cage (which you have) is - I believe - 45t. Those estimates are usually conservative, but you are definitely close, and when you get that close, the chain length becomes really important. Make sure your chain is sized correctly (big/big + 1..... Google it... and consider your 36t cog your "big"). Since you put that smaller ring up front, you may be getting too much slack in that ring.
If you are exceeding the RD chain wrap capacity it is still OK to use (if you use the Big/Big+1 chain length method), but the smaller ring/cog combos can get wonky.... just avoid them.