My wife bought me an 2006 Tricross Comp a couple of years ago, but this year I've been doing a lot of road riding, and while it's been awesome, I'd like to change the gearing a bit. It runs a 48/34 compact in the front, and 12-25 in the rear. I'd like to be able to climb easier, and descend faster, but the only 9spd rear cassette that I can find is an 11-28. Is 28 too low? I was hoping to find an 11-27. I don't want to feel like I'm crawling a long when I'm climbing. Would it be possible to change the front 48 to a 50, and then get the Shimano 12-27? Any other suggestions? Thanks!