Rear Derailuer Cage Size

I'd picked up a used 2012 Stumpjumper (XL) a while ago that came with a X9 long cage rear derailuer. The bike has a FSA 39/27 crank, 11-36 cassette and 112 link chain. It keeps throwing the chain on fast, rocky descents (even when everything is new). I've been told to use a medium cage RD (X9 with the roller bearing and locking feature). My question is do I need to shorten the chain with the medium cage RD, or will the same 112 links work?

Also, what are the individual cog sizes on a 12-36 cassette....I'm thinking of switching out the 11-36 for the 12-36. Thanks.

 

You could run a Med cage SRAM or a long cage. I would start by checking chain length.

 

Chain drop, its an existential problem. I just installed a Stinger chain guide on my trail bike. I'm hoping it will make do until I upgrade to shadow+

 

i would not use a full length chain unless you need it. i like to disconnect the rear shock and find out how much chain growth the rear suspension really needs and figure it out from there.

don't you have a c.guide?

 

If buying a new one I agree but a long cage is perfectly fine here. If he goes to 11-36 he is at the max capacity of a med cage.

 

I didn't say anything about his derailleur.