oh man, i feel the OP's pain. i'm looking at buying a Wilier frame this week sight unseen (new) and trying to decipher what the deal with measurements is, is doing my head in! i have only ridden steel frames so my current two bikes are both 56cm, with the carlton being a trues 56tt/56st and the GIOS being a 55tt/56st with longer stem. so as far as Wilier is concerned, i feel i should be getting the Large, which seems crazy to me and i feel very much a medium kinda person, but i'm just on 6foot with lanky-ish legs so i guess it's right! its just so hard to bite the bullet on these things! good luck amongst the confusing numbers!