Before you assume that all baselayers are created equal, take Castelli's Core Mesh 3 Short-Sleeve Baselayer out on a summer ride with an open mind. Rather than focusing on providing breathable insulation, a warm-weather baselayer like the Core Mesh 3 actually helps you stay cooler. The crew-neck baselayer fits like a second skin, which allows its polyester mesh fabric to instantly pull moisture off your skin to keep you dry and cool as you heat up under an unforgiving sun and tempo. By sitting between your skin and your jersey, this fast-drying layer prevents damp fabric from chilling you when the breeze picks up in spring or weighing you down on hot summer days, regulating your temperature better than your skin alone.