22.5 miles in 17 degree F with a 0 degree windchill (15 mph winds, got colder when it gusted to 25 mph). My upper body was toasty with a balaclava, Un-D shirt, thin base layer, and Performance Triflex Jersey. I had thin ski gloves with Smartwool liners underneath and my hands were sweating when I got done. On my legs I wore bib shorts and some XC skiing pants. My knees were a little cold. Then there was my feet. My toes were frozen solid (and in pain) even with thick Smartwool socks and neoprene booties. Someday I'll figure out how to keep those toes warm.

And if it matters, I'm always warm. I keep my house at 62 F in the winter and am comfortable.