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 all fabrics that bear the brand name is quantifiable as literally windproof, a status awarded according to air permeability testing. While the DWR (Durable Water Repellent) treated Windstopper keeps the elements out, the thermal layer beneath relegates moisture and internal temperature. Unlike typical winter jackets, it adapts to the needs of base-mile grinders and out-of-the-saddle climbers mid-ride. Castelli bills the Alpha as a three-layer piece, but it's much more lightweight, flexible, and non-bulky than a traditional three-layer jacket.
The Alpha features a raw edge at waist and wrist, an innovation that has been showing up on top-end gear in the cycling industry lately. Raw edges mean that hem and cuffs don't have elastic inserts, so they won't restrict movement or bunch uncomfortably while you move in the saddle. No more tugging at the rear flap of your jacket; it slides up and down your body as you sit up to noodle or tuck into the drops, maintaining coverage. Since the cuffs lay flat, they fit under gloves without having to stuff a bunched-up elastic into the wrist of the gloves. The lack of elastic also means that there's no compression point caused by an additional hem; the fabric itself is what keeps the jacket in place, and it keeps it in place relative to the position of your body, not just the highest point the hem has worked its way up to.
We've covered the functional aspects of the jacket, but we've been referring to it as a ""jacket"" this whole time, which is a bit misleading. Since the Alpha Jacket actually fits and feels more like a jersey, we'll chalk this inability to accurately classify it up to an insufficient and artificially categorizing language for describing cycling clothing. We can only assume that Castelli opted for the word ""jacket"" to stress the protective, layered elements of the Alpha, which are indeed on par with Castelli's jacket-iest jacket, the Elemento 7x(Air). Like the Elemento, Castelli rates the Alpha to stay comfortable from 53 degrees Fahrenheit down to freezing. We're confident, though, that five minutes in it will disabuse any cyclist of the assumption that this is purely classifiable as a jacket.
The aggressive cut of the Alpha Jacket fits jersey-close to your body, from the hem to the collar and everything in between. In previous generations of winter wear, this has been a significant put-off for us, as we're wary of sacrificing comfort for a streamlined fit when winter cycling already means that comfort is already at a premium. But with the cut of the Alpha, the only spot you'll notice some uncomfortable restriction is across the chest, and only while you're on foot. Once you get on the bike, the Alpha is designed to accommodate your arms, shoulders, and back as you reach for the handlebars, courtesy of the unsurpassed four-way stretch Windstopper fabric, but there's no bulge of excess jacket hanging off your front while riding. The collar is cut so that it doesnt creat