For higher exertion riding you might want to go with "pit zip" vents and/or a wind blocking front and a wicking (not waterproof) back at some temps. And don't overdress your torso like you waiting at a bus stop or sitting in a cold car if you are actively biking.. Down to about 0 F when I commuted in MN winter I'd wear a duo layer wicking/wool undershirt under a Gortex wind shell. For really cold days (below zero) I add a vest layer. If I was standing around doing nothing that wouldn't be comfortable for me at 40 degrees F, but I'm not standing around.