Do add an extra layer to your core, Red! And check out my post on the commuter thread about home-made toe covers from newspaper
I gotta admit I don't ride for pleasure at temps like these, but I do have plenty of experience commuting at around 15-20 F. And I have my clothing tuned well enough now that I get to work warm and just slightly sweaty. My toes and fingers may get cold underway depending on my speed and the wind, and while that may be a little painful, I'm still warm (and alert and all that) from inside.
Last time I misjudged the temps going home (the sun went down and the temp. dropped by at least 5 C, plus there was some wind) and skipped one layer of wool on top I could feel the same thing after a while. I got sluggish, bored and just a bit apathetic. Not good.
Winter riding is much less about badassery and much more about bundle-uppery. - malkin
1995 Kona Cinder Cone commuterFrankenbike/Selle Italia SLR Lady Gel Flow
2008 white Nakamura Summit Custom mtb/Terry Falcon X
2000 Schwinn Fastback Comp road bike/Specialized Jett