Originally Posted by
Torchy McFlux
Short-cage rear derailleurs don't work well with anything bigger than a 28-tooth cog. You swap it out for a long-cage 7-8 speed Shimano derailleur and you'll be fine.
Right conclusion, wrong data.
The cage length isn't what makes a derailleur capable of handling a 32 tooth cog. It's the geometry of the parrelogram.
The short answer is you need a mountain bike derailleur to go with your 32 tooth rear cog. If it was my bike I'd probably get a Deore rear derailleur.