The Free Aero Race 4 Bib Short from Castelli is built using extensive feedback from the professionals on Team Sky. Its general consensus is the existing Free Bibshort was already pretty well dialed and the only requests were the addition of a loop in the bib to hold a race radio microphone and one rider wanting his chamois shifted back a bit. Team Sky isn't the only one who likes it, in fact, the Free Aero Race Bibshort is the best-selling Castelli short of all time, so it knew that when it was time for an update, it wanted to make it better but not change the shorts too drastically. First up is a new leg gripper that still features a lie-flat, raw-cut edge but now has vertical silicone stripes to hold it comfortably in place without restricting stretch. Next is a new fabric that allows for better print quality and Castelli updated the seams to improve the fit and looks. It also re-engineered the bib straps with new fabrics and construction so they help you stay cooler, lie flat, and are more durable. Finally, it also receives the updated Progetto X2 Air seamless seat insert featuring one of the softest surfaces we've ever felt in a chamois.