Castelli endurance x2 bibshortscastelli engineered every part of the endurance x2 bibshorts construction to make your longest rides more comfortable everything castelli does is geared toward speed and they know that means doing some long rides long ride muscle supportcastelli continues to use the progetto x2 air seat pad due to its proven comfort and when its combined with the new endurance evolution fabric it provides excellent muscle support the bibshorts have been constructed with a perfe