I have a couple of them myself. I also have a fast carbon race bike. I, more times than not, usually choose the Tricross for rides. Such a nice riding bike. I found the sizing kinda odd due to the geometry. My road bike is a 54cm, but a 54cm Tricross felt way too cramped so I ended up going with a 56cm. If you had experience with other bikes or had other bikes that fit, I'd say base the Tricross size based off the measurements of the bike you had, but in your case, you'd better ride one or you'd be taking a big chance. Most bike shops will not take bikes back if it isn't a defect.