When planning a long ride, you want to be thinking about choosing the perfect route, not your shorts getting uncomfortable a few miles in. Castelli designed the Endurance X2 Bib Shorts to stay comfortable for the duration of your ride. Made of Castelli's Endurance Evolution fabric in an eight panel design, the bib shorts stay in place with a compressive fit made to help support muscles and wick moisture away quickly. The bib strap design has been modified slightly with this generation to help accommodate a wider range of body types.Castelli made minor changes to its top tier Progetto X2 Air chamois to increase breathability and comfort, but didn't feel compelled to alter many of the features that have made it so popular. It's kept the absence of seaming or folds in the fabric, meaning the insert sits smoothly against the skin, with a bacteriostatic layer and four way stretch in the two layer design. Sensitive ishial and perineum areas subjected to the majority of pressure during a ride receive the perforated padding seen in previous generations of the Endurance X2 to ensure comfort. Castelli also includes its GIRO3 leg grippers to keep the shorts in place, which lay flat and have a soft, not sticky, feel against the skin. On the back of the legs, reflective tabs help you stay visible to motorists if your long rides start or end without the sun.