looking at Shimano XT M786 Shadow+ 10 Speed Rear Mech, medium cage to run 1x with a ring on the front about 28t. The given max no of teeth on the info says 35 and some other listing says 36. Would I succuesfully be able to run cassettes with more teeth, 40 or 42 for eg? you would think it would be okay given single ring up front or is there just not the capicity?
ta

I use the same mech with a sunrace 11-42 cassette with no issues other than screwing the b screw in a bit. Used with rings up to 32t.

I’ve found that mech hangers can have a massive affect on what works and what doesn’t. Not that you get any say in that, the one with the frame is the one with the frame. What I mean is whether it works or not can be down to more than just the spec of the mech.

thanks guys

It’s not max teeth it’s max capacity. So if you’re on a 1x front then 11-42 is 31 teeth, your fine.
I ran the same mech with an 11-42 using a one up sprocket – works fine.