The Castelli Free Aero Race Bib Shorts have not only survived the test of multiple seasons under Pro Tour behinds, they have moved from strength to strength largely due to the intelligent feedback from real-world professionals. Designed to provide long-lasting, durable comfort, the Free Aero Race Bib Shorts will keep you supported and ventilated during long days in the saddle. That's why Cycling Plus magazine named these bib shorts the best of the best during extensive testing in 2011.The beauty and effectiveness of the Free Aero Race Bib Shorts comes from the targeted use of three main fabrics. First, Castelli developed what they call an Action Micro fabric that is particularly durable and placed it in the saddle contact regions, since those are the areas that get the most regular wear and tear. Energia Micro fabric is used on the sides and back of the bib shorts to take advantage of its outstanding stretch and return. The Breathe Micro fabric is used for the front of the shorts because, as its name indicates, it has been designed to let the fabric breathe to help keep the legs from overheating when the sun is beating down on a hot day. Perhaps nothing in these bib shorts has benefited as much from Castelli's association with professional cycling teams as the Progetto X2 Air Seat Pad. The Garmin-Cervelo team spent a year testing this short; that's a lot of saddle time to be thinking about how comfort could be improved. Since Castelli had it pretty right to begin with, there wasn't much more than tweaking going on. What it has done is add a perforated foam layer to the pad to help ventilate and keep the nether regions cooler by allowing air to flow directly onto the surface fabric. That layer sitting next to your skin is made from a four-way stretch, seamless, bacteriostatic layer designed to move with you, reducing any bunching and friction. The cushioning layer consists of strategically placed, multi-density foam.