I got these as a replacement for the 2012 Velocissimo bibs from Castelli, which now sport the plunging "neckline" of Castelli's Aero Free and Body Paint shorts. Which show lots of bare belly when you raise your arms. No more Castelli shorts for me.
These Giordanas look great, and the mediums fit my 5'10", 160lb body very well. I also wear medium bibs in Castelli sizing, but, just as the knowledgeable live chat guy told me, the Giordana shorts are JUST a hair larger, or I should say, less tight, or compressive for the same size. Since Giordana says 28"-32" is medium, and 32"-36" is large, my 32" waist was right on the border. Chat guy wisely steered me toward the mediums. LOVE Realcyclist!