Originally Posted by
cale
Don't second guess the frame size. Never.
There HAS to be something that make your CAAD's in 54 and 56 balance out so that they both fit. And you said the 55x55 was okay which I took to mean a little scrunched up. I'm 5'10-3/4 with 32" inseam and relatively long arms and fit a 56/57 great. I hear guys my size get along with 57/56/55/ but 54 would seem short for your 33" inseam and the stem would be over 12cm IMHO.
I think you'll end up trying a stem or two when you build the bike. That's pretty much par for the course.
The CAAD 54 with 120mm stem worked but I probably could have used a 130mm stem to be stretched out properly. The 56 felt like I could not get low enough sometimes but I did have the cone spacer on top of the headset so I probably could have gotten a low profile cap and fixed that.