As we prepare for another season of cold weather cycling, it behooves us to pause for a consideration of winter climbing. Climbing makes you hot, so your body produces sweat. But then you hit the top, and the fast descent through cold air cools everything off including the sweat. Since this chain of events usually means finishing a ride in clammy frigidity, confronting one or a series of taxing climbs during a winter ride is a daunting prospect. In yet another first, Castelli produced the genre defying Alpha Jacket for just such an occasion. Your need to climb may be due to the restrictions of local topography, the desire to interrupt the monotony of winter base miles, or your own inability to just take it easy on a training ride. Whatever the case, the most immediately obvious feature that sets the Alpha Jacket apart from its competitors is also the one that addresses this, the ultimate problem of winter cycling: how to eliminate sweat on the climb without freezing. The Alpha Jacket's thermal layer is detached from the Windstopper layer in the front, so unlike with other winter jackets when you unzip the shell to let in the wind, you're only exposing the thermal layer, not your bare chest or base layer. Since the thermal layer is protective but permeable, it lets the cool in evenly, all over, not just through one frigid blast at your sternum. The thermal layer is also more breathable than the outer Windstopper fabric, which means that it evacuates moisture from your microclimate even as your body creates it on the climb. At the top, you're as dry as possible, so you can zip up and descend without worrying about cold sweat on the rest of the ride. And if the climb is too hot even for the thermal layer, you can unzip it, too, allowing for even more microclimate control. As alluded to above, that microclimate is protected by Gore's Windstopper 150 fabric, a lightweight, four way stretch version of the venerable cold weather armor. The Windstopper 150 like.