A few days ago, I quickly read something here that certain bikes/frames were properly measured from Center to Center (center of crank, to center of top tube, i think). Then, I saw in the marketplace, someone selling an early 90s Specialized Allez, which is more or less what I have (a '92 or '93 Allez Comp). In there, they state it is some number of cm, CtC measurement for the frame. Should my Allez be measured "CtC"? I just bought it, and the seller stated that it was a 56 cm (he is the original owner), but I measure it conventionally as a 58, measuring it from the crank center to the juncture of the seat post and top of seat tube. Which method would show me how Specialized sized this frame?

Danny