The effects of the transitional seasons are felt by cyclists from all walks of life. Whether you're a 'cross racer, a criterium sprinter, a singletrack enthusiast, or a professional, you've no doubt had the regrettable experience of being caught unprepared in the volatile elements or rapidly changing temperatures of late fall or early spring. The pro racer Gabriel Rasch came up with the idea of a jersey that could be paired with Castelli's Nanoflex Arm Warmers, so Castelli called the product Gabba, which is Rasch's nickname. It only makes sense that the second generation would be called the Gabba 2 Jersey. The Gabba 2 embodies Castelli's ethos of minimalism in construction by using as few fabrics and seams as possible. With the exception of the stretchy Nano Flex inserts in the underarms, the entire jersey is made from Windstopper X-Lite fabric. Windstopper X-Lite has 1. 4 billion impossibly small pores per square-inch that guard your microclimate jealously. They don't let wind in, but they do let moisture and water vapor out. This isn't just based on vague marketing copy, though. The science behind Windstopper X-Lite is measurable in a rating called CFM, which stands for cubic feet per minute, used to measure the volume of air that passes through a fabric in, you guessed it, one minute. In order to be considered truly 'windproof,' a fabric must register a CFM of equal to or less than 1. 0. The Windstopper X-Lite fabric actually beats this rating, so you're guaranteed a top that is literally classifiable as windproof. It's also treated with a water-repellant finish, so it keeps the warmth in and the rain out while wicking moisture from your skin. Gore-Tex's Windstopper is amazing stuff, but it's not limited to Castelli. The new Gabba 2 had to stand out in some other way. Castelli was birthed by the work of Vittore Giani, a tailor from Milan, so it plays to the strengths of its legacy: sexy aesthetics and uncompromising fit. The fit truly defines the jersey, but...