"There's always room for improvement" is a saying that Castelli takes very seriously. So despite the Free 3 Aero Race bib shorts being the best-selling Castelli bib short of all time, and despite nearly 100% positive feedback from Team Sky, Castelli did what they always do and took a good thing and made it better. For 2019 the Free Aero Race 4 bib shorts have received an overhaul. Featuring a new leg gripper that maintains its lie-flat raw cut edge, but now has vertical silicone stripes to keep it in place without restricting stretch. Built from a new fabric that allows better print quality for team production, which is exactly what Team Sky will be using in 2019. The bib straps have also been re-engineered with new farbrics that are more durable, more breathable, and lie flatter. The seams have been updated to improve fit and make the shorts look better on your body. Finally, the Free Aero Race 4 will feature the updated Progetto X2 Air seamless seat pad, the softest chamois Castelli has ever designed.