This winter has been so hot here in Colorado that I've forgotten how to dress for winter cycling. A cold front came through last night, it snowed, and the temperature this morning was in the high teens Fahrenheit (minus 8 or so Celsius).
I put on my Patagonia featherweight base layer and a midweight fleece middle layer on my legs and torso. Another layer of fleece went on my torso. Bridgedale wool socks, plastic bags and shoes covered my feet. Wind and wet proof shells covered my legs and upper body. A balaclava covered my head and face. Heavy ski gloves and helmet completed my cold weather ensemble. I had three layers on my legs and a whopping four layers on my torso. I headed out the door and hopped on my red fixie, nice and warm and toasty.
Experienced winter cyclists already know what happened during my five mile bike commute. I unzipped everything I could, but I arrived at work drenched in sweat. I was dressed for below zero F (-20°C), not the relatively mild temps we had this morning.
The usual solution is to regulate heat by regulating my activity, but I rode my fixie on ice-covered streets. If I go slow in those conditions, I'm expending a ton of effort anyway just keeping my bike upright on the ice. I might as well get some distance for the energy I expend by going fast.
Here's the general tip for winter cycling: If you're comfortably warm when you start your ride, you're probably overdressed. I should've checked my own winter cycling clothing guide that I created two years ago.