If you're fortunate enough to live in a climate with proper transitional seasons, then you know the joys and hardships of cycling in the fall and spring. There is no finer way to experience a landscape in flux than from the saddle. The fall colors, the new shoots of spring cycling lets you move through neighborhoods and landscapes to experience as much of the fleeting changes as possible. But times of rapid change are by definition also tumultuous times, and nothing says transitional tumult like wind. Sportful claims that the WS Ascent Jacket has become a seasonal favorite amongst its staff. Given its high breathability and strong but not stifling wind protection and insulation, it's easy to see why. A cursory look through Sportful's line of jackets might give you the impression that Windstopper 4 Way Mid falls between the 4 Way Warm and 4 Way Light farbics. You'd be right. The insulation in the middle sibling is 25% lighter than in the warmest, so it won't protect you in the year's most extreme temperatures. It is still water resistant, remarkably stretchy, and windproof, which is quantified with a rating called CFM. CFM stands for Cubic Feet per Minute, and it's used to measure the volume of air that passes through a fabric in one minute. In order to be considered truly windproof, a fabric must register a CFM of equal to or less than 1. 0, and anything bearing Gore Tex's Windstopper label including the 4 Way Warm material either meets or exceeds this rating. ThermoDrytex XP is a synthetic blend that omits Lycra, so it offers more insulation and protection than blends with Lycra, but with less flexibility. Obviously, there are some areas of a jacket where ThermoDrytex SP's qualities would be ideal and other areas where the flexible protection of the Windstopper 4 Way Mid would be more appropriate. Sportful uses the former on the back, whose only job is to stay in place, and the latter on the front, shoulders, and sleeves. The jacket's fit is more rela...