Righty, going 1 x 9 from current SS.

Going to use SRAM 990 11>32 rear cassette.

So can I use any 9 speed rear mech?

I’m assuming I don’t need to use long cage but am confused about what benefits of

M770 rapid rise

v

M772 shadow

Will be used with XTR 9 speed shifter…..

rapid rise goes ‘backwards’ to prob what you’re used to. i.e. the spring sends the mech to the low gear (the biggest sprocket). Long and short of it is the triggers on your shifters move the mech the opposite way.

shadow is just a ‘low profile’ normally sprung mech – it’s useful on some full sus frames as it prevents the mech clattering the chainstay and doesn’t protrude from the frame as far as a normal mech.