Ernest Shackleton led his infamous trip to Antarctica aboard a boat he re-named the Endurance after his family motto: Fortitudine Vincimus (by endurance we conquer). A painfully apt name as Shackleton and his crew survived twenty months at the bottom of the world, an endurance feat we never want to get near. Endurance is also an apt name for these Castelli Bib Shorts, as they're made to survive epic bike rides.Castelli makes no secret of their design ideas when it comes to shorts. Start with the chamois and build from there. These share many design traits with the top-shelf Free Aero Bib Shorts without sticking you with the same kind of price tag. The pad you sit on is Castelli's Progetto X2 chamois. It's a three-layer stretch pad. The top layer is soft and seamless bacteriostatic polyester fabric that wicks moisture away from your body. Underneath the top layer is a perforated viscous comfort pad located directly under the sit bones and the perineum to neutralize those high-pressure areas. The final layer has variable thicknesses. It's micro-thin at the edges and increases in thickness en route to the thickest area, under your ischial tuberosities. The legs have Giro++ grippers, just like the Free Aero Shorts. Pronounced "Giro Two" in Italy, or "Giro Due," this is a single-layer gripper that integrates gripping material into the fabric as the shorts are being made, so you can barely feel them even though they hold firmly. This technology is pretty cool; they've taken 43% Lycra content fibers and stitched them inside PowerLycra, which is 24-28% Lycra. As you stretch the material, the 43% fibers start to appear on the inside. Giro++ grippers are soft and rubbery and grip great.The body of the shorts have been simplified. They use an eight panel design to wrap around your body. The front and rear panels are made from Action PowerLycra, which is highly abrasion resistant. The side panels are made of Energia LycraPower. It stretches more horizontally than vertically so it offers good muscle compression. The ribbed knit surface also helps a bit with aerodynamics. The bib is a Lycra mesh that's thin, breathes well, and has great stretch.While they simplified the design a bit, there are still smart design flourishes. Four-needle flatlock stitching works great and helps maintain the compression. The rear shorts panel that moves from your glutes up your back until the mesh takes over is also a savvy touch. Because of this, they fit better, closer, and they also wick better.The Castelli Endurance Bib Shorts come in Black, Red, and White. There are reflective inserts on the back of the leg grippers. They come in sizes from Small to XX-Large.