A lot depends on which Cannondale we're talking about, too.

A Synapse has a 3cm higher headtube than a Super6 of the same frame size, for instance.

So if "sporty looking" for you is low headtubes, you have to get the right model.

You want a 54cm stack height, the 51 Synapse has 54.9, the 48 has 52.9

In the CAAD10, 54 has 54.5 stack. 50 has 52 stack, 48 has 51.7.