Bike Fitting

Just went through the competitive cyclist website fit calculator:

Interestingly it would put me on a frame with a top tube 1cm shorter than my current bike, with a stem almost 1cm longer.

So, overall not much in it, but just wondering why they'd take distance off the top tube and add it to the stem?

The model used by them is really out-of-date. It's based upon a variant of Genzling model and is, at its core, for frames with horizontal top-tubes, quill stems and down-tube shifters. Today's road position is different. Today people spend most of their time on their hoods as that is also where their shifting controllers are located. In response to the change in position, modern road bars have also comparatively less reach and drop.

From the values spit out I would assume that you have average morphology. A typical 58 c-c frame and a 120mm or 130mm is what they suggest. I would guess that you are ~188cm (6'2") and wear size 11 shoes?