Some folks bike here with "studded" tires on their bikes, but I don't trust that. On a car, the studs don't help in slushy snow, they only really help on certain kinds of ice. And doesn't it take a good bit of weight for the studs to "bite" into the ice? Still, the few cyclists I've seen out there in the snow seem to be doing all right. My doctor that I had an appointment with this morning said he'd biked to work (I came running in 10 minutes late with yak trax on my boots). He said you just need those tires, and the studs have to be not only in the centre tread but also up the sides a bit.