I have a Shimano cassette with an 11-34! It's a mountain bike cassette and it's perfect with the compact up front. They are compatible The difference between a 30 and 32 isn't much, but with the 34, I certainly can feel the difference between it and my other road bike that has a triple and an 11-28 cassette. At first, the wider gear spread on the compact did bother me, but after a few months (3-4) I found my groove and I really love the combo. I've had secret thoughts of changing out my other bike to this combo.