Originally Posted by John E
Yes, please do. If you have a short-cage derailleur, you cannot run more than 24, perhaps 26, teeth on your largest rear cog. The key is the pivot point of the cage. If the pivot point is lined up with the jockey (upper) pulley, you have a wide-range derailleur, which should be able to handle 13-32 or even 34 teeth, even with a 10-tooth drop in front. If the pivot falls between the two pulleys, you have a racing or narrow-range deerailer.
I think this depends on the make and vintage of derailer.It works for some old suntour stuff I have but doesn't apply to a newer shimano stuff. There is more to it than cage length too,as that is mostly about wrap. Parallelogram geometry is a serious part of ability to shift a big cog.