54cm road frame with 110mm stem and a 54cm TT frame with a 90mm stem both seem to work for me. I'm 5'10'. I also have a 58cm with 120mm stem and a 56cm with an 80mm stem....so you know what... I really couldn't tell you. I'm a freak and all those configurations were comfortable enough for me for long times on the saddle.

Thats said my optimal fitting says 54cm... high seat... long stem in the 120mm range....