Before parting with the 54, I suggest that you should make a small picture with your preferred seat height current from the saddle nose to the handlebar center and the height difference between the seat and handlebar height. If I were to make an educated guess , I think that If you go through the sell/ buy the next size down (2 cm- 1 thumb width smaller, that it is not going to make much of an an appreciable difference.) If possible to go a store who has a 52 that you can use your dimensions and set it up to try it out?