Castelli's Free Aero Race Bib Shorts hide their assets in their name. Namely, free speed, aerodynamics, and race-oriented. The Free Aeros utilize a variety of surface textures, fabrics, and time in the wind tunnel to deliver a claimed 10-watt savings at 50kph. This may not seem like much, but those savings add up over even a two or three hour ride, and could mean the difference between enough power for a sprint and pedaling lamely to the line. At the core of the shorts sits Castelli's Progetto X2 Air chamois, with one minor-but-crucial improvement --a softer face fabric. You get all the support and chafing resistance you expect from the Progetto, but it's a bit kinder to your skin now. We'd be remiss to not mention the lightness of all of the fabrics in the Free Aero Race, in part because they're comfortable and airy on even the hottest days, but also because you're going to want to apply a bit of sunscreen at the leg bands.