Hello all, my bike has 10speed mirage drivetrain, I love it with the exception of the cassette. Not enough low gear for me. I admit I'm still very new cycling but I'd love a little more low gear. I'm assuming my bike came with a short cage rear derailleur, and its ultradrive if that makes a difference. I found a couple of cassettes I'm interested in but I'd like to know of there will be compatability issues. I can only assume there will be. I have a standard compact crank, 50/34 and a 12/25 cassette now. I see there is a 13/29 and a 12/30 available. I'd love to get the 12/30 if it will work but I guess thats why I'm asking here. I really dont know what will work, can someone enlighten me?