buffaloforwarded me this article today and I had to think about it because I think I do this unconsciously. Good info:

Winter riding presents additional challenges, a more cautious approach. Here in the mountains it often dictates shorter rides as we wait for the sun to get high enough to warm the roads a bit and clear the icy spots. Even so, with the sun staying low in the southern sky there are shadowy spots that never really warm during the day. When extended cold snaps come it's prudent to avoid the roads that have a lot of these and stick to the lower valley rides.   

Makes sense. Black ice can ruin your whole day. The only really cold weather mountain riding I can remember doing was way out West.

I used to do it quite frequently. Not so much anymore. Plug in gear makes year round riding much easier.

I read this article too. It was a piece of great information. I used to ride in winter but now it is serious to ride in the snow. Although there are great winter tires. If I ever ride in winter, I would go for Michelin.