Riding in winter is totally doable, definitely calls for proper clothes and and several extra notes for safety and maintenance. Check out those threads Dan linked, especially the "Winter Motorized Bicycling, tips and tricks". When the roads are clear and dry, there's not much difference other than clothes and being careful of frostbite. After or during storms is a different animal. Snow isn't so bad, but you just need to slow down. Straight lines are great, turning needs to be slowed, and you've got to keep a serious eye out for ice. If you've never had your front wheel go out from under you before on ice, it's a very special experience. It happens faster than you can believe. The other thing to remember, is that anywhere north where plows are operating, they pose a significant danger to you. They aren't expecting to see bikers out there in a storm or even on a dry day afterwards when small plow trucks are still cruising around with their plows on their trucks. As winter gets on and the snowbanks start crowding the roads, there's less room for everyone, and no one is expecting a bike to be on the road. It also gets dark much earlier, especially here in Maine being so far east in the time zone. For that reason and all the others, I'm not in a place where it's particularly safe for me to be commuting to and from work, but I go out for short fun rides during daylight hours. I mostly stick to my pedal bikes in winter just cause I need the excercise anyway!