I have an 05 roubaix comp that I love. I am 5'7"1/4 with a 32 inch inseam. The fit said I measured for a 53, well I took the 54 with a shorter stem and it worked out fine. For me the ride with the zertz is excellent and I also use it for sprint tris with bars on. It sounds like a 54 is what you need, but try it before you buy it.