I trained during winter for the first time last year, and I wasn't entirely satisfied with my choice of jackets. I used a Mammut Brisk, an unorthodox choice, but it was made of 100% Windstopper fabric, had no thermal components, but did have pit zips for ventilation. In moderate temps (40ºF), I wore it over a L/S jersey, and added a wicking base layer for colder temps. Riding at 20ºF was comfortable with the jacket over a 200 weight fleece layer. Unfortunately, the pit zips were very contrary when I tried to unzip while riding.

I'm really interested in getting a jacket with zippered chest vents instead, but all models I've found have a varying mix of wind-proof panels and thermal layers, and all would seem to be warmer than the Brisk (Castelli, Giordana, Zero RH+ and Pearl offer this type of jacket, maybe there are others). These jackets are rated for as low as 20ºF and as high 60ºF. Are these ratings based on minimal layering underneath? I'm sure the Mammut Brisk wouldn't be rated for 20ºF, but with the right layers, it's perfect. I want to avoid buying a jacket that would cause me to overheat, so any experiences anyone cares to share would be appreciated.