So if you're brave and or skilled, I suppose almost any bike would do. Some of you guys are pretty awesome and could do it on slicks, I'm sure. I, however, am not.
If there's snow/ice going on, I try to stick to my hybrid. It has tread (which makes me feel good psychologically) but is a BSO bike that's a little big for me. It has a relatively high center of gravity and I'm learning why rim brakes are less than ideal in the winter (works fine in the rain here, though).
I'd not given much thought to the idea of a winter bike outside of snow tyres and the occasional pro-29er guy who really likes the large tyres. While tinkering with the fiance's beach cruiser, though, I had a few thoughts. It dawned on me that her cruiser had a few features that would make it better for winter riding than my hybrid.
Here's my vision of a good "winter bike". Let me know if my reasoning isn't so great. These are in no particular order, and some are obviously more important than others:
1) Capable of taking snow tyres. This means some good clearance for cleats, and capable of taking a rim that seats commonly available studded tyres. The exact type doesn't really matter here so much.
2) Wide tyres, like cruisers. A wider tyre would allow for more studs, more contact surface and thus better traction. 1.75", 2", that kind of thing.
3) Relatively small tyres. 700c -> 29" seems to be pretty popular. However, most wider tyres also tend to have a smaller diameter (but not always!) - 26" seems like a good size. Shorter tyres allow for a higher bottom bracket without putting your bike's CoG as high, or somesuch wizardry.
4) Low CoG. The lower the center of gravity, the easier it is to control. Lower frames in general might yield less issue if you do fall.
5) Heavy frame. A heavier frame (as opposed to a lighter one) with a low CoG would be more liable to be easier to control. Puts more weight on the wheels.
6) Wider wheel base. This makes handling smoother and might prevent spills that shorter wheelbase, "twitchier" bikes may experience.
7) Step through frame. When you're dressed up and on questionable surfaces, a step through would be easier to operate. These also tend to be heavier and feature a lower CoG.
8) At least one non-rim brake. Ideal would be a front drum, but a rear coaster brake might be ok. Rim brakes really do have issues with ice. You shouldn't be traveling too fast in icy conditions, but you still need to stop. Having no rim brakes at all might be even better, as there'd be more room for ice to clear.
9) Hub gearing. I got to experience what icy snow was like in my derailleur. It's crappy.
10) Enclosed drive drain. This prevents mechanical issues due to ice getting in places it isn't welcome.
11) Upright or semi-upright posturing. I'd imagine it would spread your weight more evenly between the wheels, and would be better for visibility for all involved.
12) Good, grippy, well cleated pedals. I have some really grippy ones on my road bike, but basic ones on my hybrid. Found myself wishing I'd moved them over! Snow gets on your shoes, makes pedals slippery. Clips/clipless are probably a bad idea, as they slow how easily you can get out of the pedal if need be. Also, a clipless system doesn't appear to be a good choice for walking in snow, as who knows what that'll end up doing to the mechanism?
13) Fenders. Yes.
These are frame/mechanical stuff that would be ideal. Of course, there's the issue of lighting and other assorted visibility things. I thought about panniers on the way in the other day, for putting heavy things in like cars do with their beds/trunks. Bags of sand for them, for example, to increase traction. No idea if that's good for bikes, however.
So, have I got my head on straight?