Depending on the temperature and length of ride, I wear either merino wool long underwear or wool cycling tights underneath whatever pants I would normally wear (usually BDUs or Dickies). I also have wool long-sleeved shirts and a rain jacket for up top, with more layers in between depending on temperature. Thick wool ski/snowboarding socks and my normal clipless shoes down below. Full finger PI Cyclone gloves keep my fingers warm and a balaclava or wool cycling cap and glasses for my head and face/eyes.