MOUNTAINEERING TECHNOLOGY FOR THE BIKE
We looked to the world of ski mountaineering racing, where the competitors obsess over weight even more than we cyclists do, yet their insulation is a matter of survival, not merely comfort. And with ski mountaineering being an insanely aerobic sport, breathability is paramount.
The construction of this jacket is similar to that of an insulated alpine shell, with an insulation layer sandwiched between woven inner and outer layers. Unlike most mountain jackets, though, the woven shell isn't completely windproof, instead, we've left a small amount of permeability.
The small amount of air that gets into the jacket picks up the moisture and evaporates it more efficiently than any membrane fabric available. The middle layer is a puffy insulation layer that we make in polypropylene partly because it's insanely light (specific gravity 0.6g) but also because it won't pick up moisture from either sweat or rain. These limited-stretch fabrics require a new cut, so this piece fits slightly looser than your race jacket. If your winter goals are new Strava PRs rather than winning races in the spring and summer, you're better served by the Alpha Light Jacket or a Perfetto. But if your goals involve a real rather than virtual finish line, this jacket will make your winter riding better.