Has anyone does this? I was using a compact double (can't remember the exact gearing off the top of my head), but really struggling when the hill grades went above 10%. I have some long hilly events coming up soon, so I swapped the rear cassette for a 34 tooth mtb cassette. I'm just curious if anyone else has done this and if he/she liked it? There definitely is a larger gap between each gear, so that's been the only thing to adjust to so far.