Knocking out a stiff climb always sounds like a good idea from the air-conditioned comfort of home, but we always forget how punishing a climb can be when the weather’s hot and the grade is steep. We might forget how much the last climb stunk, but Castelli has a better memory, so it designed the Climber’s Women’s Jersey to keep the heat turned down when the summer heats up. Castelli employs 3D fabric architecture throughout its line, and the Climber’s features Flusso 3D in the front and Strada Pro 3D in the back. Flusso is so light that you’ll hardly notice it, and Strada Pro is hyper-efficient but has a little more structure to support the three pockets on the back of the jersey. Both wick moisture and breathe exceptionally well to keep you cool and dry. Castelli also engineered the Climber’s with a built-in bustier lining for comfortable support. AirMesh armbands keep your sleeves in place and provide an aerodynamic fit, and the 3/4-length zipper reduces bulk and keeps the front of the Climber’s even sleeker and faster.