I have two road bikes, one a modern Cannondale 58 cm and one a larger 80s Schwinn, size 61cm (both sizes based on seat tube c-c measurement). The Cdale is the right size for me, however, while the Schwinn is on the tall side, both bikes have the same 57.5cm Top tube measurement. The ST angle on the Schwinn is steeper at 74degrees vs. the Cdale's 73. HT angles are also different, 73 for the Schwinn and 73.5 for the Cdale.
So here is the issue. While both bikes are comfortable to ride, they just feel different and I am curious to understand why. I am using a setback seatpost on the Schwinn to compensate for the steeper ST angle, but even though I have same stem length on both bikes, and the saddle to bar drop is about the same (2 inches),when riding the Schwinn I feel like I am positioned out over the handlebars, on the Cdale I feel more centered. I think my saddles are positioned correctly on both bikes relative to the pedals (I.e. Not to far forward on the Schwinn) so I can't figure out what accounts for the sensation I have on the Schwinn of being positioned out over the bars. Is there something about the taller seattube that would account for this even though I have compensated for the steeper angle with the setback post?