Originally Posted by
CliffordK
For a horizontal top tube, it is measured center to center (and most people seem to do that).
I don't agree with that. Both center-to-top and center-to-center have been used by manufacturers, bike shops and individuals. In my experience, center-to-top has been more common than center-to-center. The best thing is to always specify c-to-t or c-to-c along with the measurement.
I have the exact same height and inseam as the OP and I usually ride a frame anywhere from 56 to 59 cm c-to-t. The bike shown looks way bigger than 54 cm to me. I'd guess 58 to 62 cm. As mentioned by others, having a little room for the family jewels and having a top tube the right length for your torso/arm length are the most critical measurements. For us older geezers with sensitive backs, it's also best to get something relatively tall in the range so that you can have the stem as high as the saddle.