A query came into the website asking help on biking through the winter. Gary’s answer would seem to have value to a lot of our riders especially considering the time of year, so we’ve posted it for everyone’s convenience. Any readers who have their own suggestions or experiences are urged to leave them in the comments section. 
I highly recommend studded tires. When I was younger and more reckless, I used to ride in the winter without them, but would occasionally take a spill on ice. I feel much more confident with studs. The downsides are that the tires are heavy and have lots of rolling resistance  My ideal setup is to have one bike with studs (for days with freezing weather) and another without, for the warmer days. Studded tires are no better than knobbies on snow; what they’re really meant for is to deal with ice.
I would look for tires with carbide-tipped studs. A couple of companies (Innova and North45) make tires with steel studs, but those can wear down completely in a single season. The carbide studded tires cost more, but can last for several years (I’ve been using one pair for four years now).
Studded tires are expensive. In the past, I’ve been able to save money by ordering from www.starbike.com, a German online retailer. But you usually have to put together a very large order to avoid crushing shipping fees, and I have no idea if the exchange rate is still favorable. I think Towners carries studded tires locally, but I don’t know about other shops.
I’ve ridden several years with plain glasses, but started using goggles last year since my eyes water in temperatures below 15 degrees or so. I had to do some experimentation to find goggles that wouldn’t fog over. If you’ve had problems with fogging in the past, I would stay away from cheap goggles. I use a pair of Scott goggles with an anti-fog coating that seems to work well and that fits over my prescription glasses. They even have a tiny fan that turns on in high humidity conditions. (That might be overkill — it’s my understanding that the amount of moisture in one’s breathe is highly variable and you might not fog up in conditions that would bother me.)
Keeping my feet and hands warm is a big problem for me (but might not be for you). I use these Bar Mitts on my road bike:
But if you have a flat-bar bike, a good pair of mittens will work nearly as well. If not mittens (which interfere with dexterity), I would recommend “lobster gloves” like these:
If you use non-clipless pedals, I would recommend warm-weather boots in the coldest conditions. If you use clipless pedals, then you can buy winter cycling shoes (they tend to be quite expensive — $200 to $300) or neoprene overshoes. Some people cycle in the winter with clipless sandals and heavy socks, but I’ve never tried that.
You might also want to take a look at the icebike website:
The content hasn’t been updated in several years, but there is still some useful information there. Also, there’s a related icebike mailing list that is still active:
Hope that helps.