Cannondale Aficionados / Owners

It just seemed counter-intuitive that moving up from 60 to 63 would result in a shorter reach, but when looking closer at the chart there is a difference in seat tube angle too.
The -1 degree seat tube angle (between 58 and 63) cancels out the +2.5 cm in effective top tube length and results in the same reach.

It is why TT length is a poor measure of fit.

This is interesting and I'm trying to understand this, so don't blast me just yet.

But even though (for example) the 58cm and 63cm SuperSix Evo have the same reach, if you were to put the saddle at the same position in the seatpost and run the same length stem, there would still be a 2.5cm distance difference between de tip of the saddle and the middle of the handlebars, right? So you'd still need be taller for the 63cm than for the 58cm, even though they have the same reach?

And doesn't the slacker seattube angle of the 63cm frame increase the distance between the saddle and handlebars even further, between the 58 and 63cm frames? Come to think of it, because the seattube is under an angle, raising the seatpost will increase the distance as well, no?