Which derailleur is it? I'm stalled on converting my MTB , has an older SLX 10 speed rear mech, I've got the 11-42 and a Nw chainring, just trying to work out the derailleur I can use that will work without issues (clutch would be nice)
M786 + 40t front NW ring. Works a charm, shifts on the button and chain tension is always spot on. Even with the bike loaded up, I've yet to have a mis-shift or need adjustment.
I run one of those. Works great with that derailleur. Some of the jumps in gearing are a bit annoying, but it's understandable and you get used to it.