Cinelli sizing

I'm confused over the sizing of their frames. A small mash parallax which is a 52cm measures 480mm centre to centre on the seat tube and 513mm on the top tube. I have a Cannondale 50cm frame which measures 500mm on the seat tube and 520mm on the top tube which I'm selling because it's to small and was considering a 52/small Cinelli as an option. The mathematics tells me the Cannondale is bigger. My point being that the 50cm Cannondale is actually bigger than the 52cm/small Cinelli. Anyone any views on this?

If I'm looking at the right models the stack for Cannondale is 523 and the reach is 378. For the Parallax it should be 504 and 383. So actually the Parallax rides longer. But I think you would have to be a pro to really be bothered by differences this minute. You can always move the seatpost or try a different stem.

Not sure where you got those measurements from but they look way off the mark to what I've been looking at 😀

Parallax geo: https://www.geometrygeeks.bike/bike/cinelli-mash-parallax-2016/

Not sure where to find the exact geo of your Cannondale if you know it's a 2007 CAAD5 105 groupset then it shouldn't be too hard to track down then you can plug in all the info from both frames to http://www.bikegeo.net/# and compare them.