Originally Posted by
DaveSSS
If a longer inseam (and hence saddle height) are accurately known, then the stack height should be proportional to that saddle height, to produce a given saddle to bar drop. The OP claims to have a cycling inseam that's only 6cm longer than mine, so the other 21cm must be torso length. A large frame size, might fit his torso reasonably well, but it sure wouldn't go with those short legs.
The geometry chart that I found also listed a much taller stack than the OP listed, so a comparison of the head tube length should be made to see it the OP's bike is really a 61. A stack of 630mm shouldn't be needed. That's over 10cm more than I need.
Again, you're almost a foot shorter and have very different body proportions than the OP. Using your inseam and bike fit parameters to determine the OP's correct frame size is misguided. MidTNBrad makes for a much better comparison, as he's only 1.75" shorter than the OP, also has a long torso, and is currently riding a Cervelo with the same geometry as the OP's frame.