check the cpaacity of the mid cage. might be 33T

compare that to what you need for what you’ve got:

Big chainring minus little ‘ring + biggest cassette sprocket minus smallest sprocket

eg 36-22+34-11 = 13+23 = 36

I wrecked a med cage slx with a m666 double and an 11-34 cassette. It’s just outside capacity. You need to do the sums!

Someone says it’ll be fine, someone else indicates that it won’t work, kit will get destroyed!

I’ll do the maths….

I reckon there’s maths and there’s reality. I don’t know what the SRAM capacity is, and IIRC the Shimano stated capacity is smaller than SRAM. They have to allow for idiots people putting the drivetrain into big/big and stomping on it with maximum force. In the real world, just make sure you don’t do this. I’ve been running my 36/22 and 11/34 with a medium cage for 3 years without problems

I’m using 36/22 with 11-32 and an SLX medium cage mech (GS) at the minute, theres plenty of capacity left on that setup for a 11-34 IMO, although the SLX M662 mech only seems to come in Medium and Long, and the “Medium” isn’t all that short when you look at something like a saint…

I can only imagine you would use a long cage 9 speed shadow mech if you wanted to use an 11-34 cassette with a triple, and for just about everything else (1/2 x 9) a Medium would be more than ample…

Actually does anyone need a 11-34 cassette with a double though? I mean as a gear 22-34 is pretty spinney…

Why not stick with an 11-32 cassette unless you want to run 38/24, 40/26 or 40/28 up front, then 11-34 might make a shade more sense… Right?

I am running 39-26 X0 chainset up front, 11-34 at rear, with medium cage XO mech. no problems at all.

39-26 + 34-11 = 13 + 23 = 36.

SRAM medium cage Xo capacity = 37 so its fine, but I believe you can go pretty close to the limit if not a little over.

EDIT in fact its the same medium cage mech i was running with a 44T up front before I went 2 x 9 and there were stil no problems there either with same mech and casette.