Well Sin, if it's flat, I'm sure you can use it, but you'll be in your 42 alot. No offense, but from your other posts, I don't know that you're strong enough to make good use of what a 55 would give you, but not to worry, 99% of all riders aren't. If you're riding the flats all the time, a 53 x 42 or 44 with a straight block in back is nice.