My educated guess is that you'd be best off on a 52. This gets you a top tube that is useful for your long torso (you have the torso of someone who would ride a 54), while only penalizing you 1.2cm more standover height than size 50. I'm 5'4" with a 30" inseam and prefer a 50 or 51, but have one traditional 52 that fits fine.

Go smaller and you'll be looking at rather long stems, and I've found that some smaller sizes that should fit pefectly me feel odd. And certainly the steering angles are more "normal" on a 52 than on a 50.

You will not have any clearance when standing over the top tube, but you don't need that unless you plan on jumping on your bike like the Lone Ranger.

I base my comments on this 2014 CAAD10 geo chart:
https://cannondaleclub.blogspot.com/...-inc-disc.html