I started commuting on a $300 GT Timberline, and when I bought my Kona Jake the following year I decided to keep the Timberline as my winter bike so I could keep my Jake nice and clean. Then I took up cyclocross racing, wherein after 45 minutes my "nice, shiny, clean bike" ends up looking like this:



(No, that's not a Beef Gravy Brown Cross Check.)

So I kind of lost the "nice bike" excuse. Still, I've found that winter riding does create more frequent times when extensive maintenance is required (overhauling hubs, headset and bottom bracket), and even doing the work myself that often takes the bike out of action for a couple of days. So I still need a second bike.

One thing I've found, however, is that if your "nice" bike is significantly more pleasant to ride than your "winter" bike then you are likely to start hating to ride the winter bike (even if it was fine before) and the "n+1" syndrome becomes acute. My GT Timberline didn't stay long. Ideally, every bike you own needs to be the most fun bike to ride in whatever conditions you use it for. So if you're going to have a winter bike, look for something that's more fun to ride in winter than your fair-weather bike. Alternatively, you can get a nice bike that is fun to ride in all conditions and can handle winter duty and keep a beater for maintenance days. This is yet another reason to buy a cyclocross bike.