Today will be only my second sub-freezing commute of the season. The temperature is no bother - the coldest it ever gets here is about 20F. I live at the shore, a flat, windy area, and my biggest worry is black ice. My commute home is at 11PM, and in the dark you simply cant see a patch of black ice if it forms. That's a problem, so when it gets this cold I start looking closely at humidity and potential precipitation. I'll ride in the rain if it's above 40F, but around here you don't ride in the wet when temps get below 35.