I would like to echo the advice that you might go find a Ridley dealer and size out this bike. I did so before buying my Ridley X-Fire (which is a 52 cm). Even this way, I have had to add a slightly longer stem to lengthen the top tube to my needs. As a means of comparison, my road bike is a 54 cm Trek. I believe that the frame size measurements for Ridleys may be available with a google search. I have heard that the Ridley sizing tends to run a bit large anyway, so, getting to a dealer could be the best way to tell what will work for you