Hey Everyone!

I'm looking to get an ICAN A22 frame for my next build, wondering how the sizing would fit ? Looking at the 48cm and the 51cm. My current bike is a Cannondale supersix evo 2015 54cm, I feel a bit stretched out + seat is lower than I'd like. Looking at frame geometry, the 51cm doesn't look much smaller than my 54cm Cannondale. I'm 5'7, wondering which frame size I should order.

Thanks!