I'm considering adding a 11-32 mtb 9 speed cassette to my cross bike to lower the gearing for some of the sustained 6-8% climbs of my local forest roads. My bike is already equipped with a D/A 9 speed rear derailleur (long cage, I believe; is there a way to tell if unsure?), a 12-25 cassette, and a 38/48 crankset. A mtb cassette would be more affordable than going to a compact crankset at this point.
I've read that the max cog is 27t for the D/A long cage der., but I've heard of rumors that people have had success with a 11-32 cassette without having to go to a mtb rear derailleur.
Anyone here successfully try this?