Wear a cape! The cape is waterproof, but the bottom of it is open, so whatever you're sweating is sucked away by the wind. I'll combine a cape with a temperature-appropriate jersey or layers, waterproof rain paints and shoe gators. I spent days pedaling through France a few years ago in this getup. Truly crazy hard rain might overwhelm a cape, but then you shouldn't be riding, anyway. You should be drinking a cup o'coffee instead.