My old custom made sports touring frame is 52cm but it has a 55cm tt. I recently built up a 56 cm frame with a 56 cm tt. I have found the reach on the new bike to be too long but it has a 110mm stem. I am changing the stem to a 70 cm (compliments of Robbietunes)while the old bike has a 75mm stem and the reach will be almost identical to my old bike and I think all will be well with the world. Now if I can just talk wifie into a brooks saddle to match the old bike.......