-
I'm not sure about Mtb derailleurs, but with road derailleurs max capacity listed is usually what the derailleur can take -2. So a 28 cap derailleur should be fine using 30t Max cog. However this also depends on the rear triangle geometry on your frame. Sometimes same setup will work on one frame but not the other.
-
I purchased short cage, which is actually rated at 28 max (etched on the rear cage).
I suspect a cock up in marking parts used on two different mechs with the spec for the other one. There are two short cage X0 RDs, the XC one which it looks like you have, which will work with a 36T sprocket but only on a 1x set up due to limited total capacity, and the DH one which has a different parallelogram geometry and really will only work with a maximum 28T sprocket.
Bought a SRAM X0 RD as they helpfully list the max. cassette as 36:
https://www.sram.com/sram/mountain/products/x0-rear-derailleur#sm.000005qofrb2d3eycu9iq1sz2uuc1
However looks like this is only for medium/long cage and I purchased short cage, which is actually rated at 28 max (etched on the rear cage).
How conservative are the specs/what max. cassette can I likely get away with? Rating doesn't seem logical compared to other cage lengths - any chance it's just been reduced to avoid people exceeding the wrap capacity?