Snow and ice definitely will keep me from riding outdoors. One wipeout on a black ice covered bridge taught me a lesson on that!

Last year, I decided that it wasn't worth riding outside when it's really cold---say below 20-25 degrees. I ride for endurance, so I'm usually out for 90 minutes or longer. In those types of temps, even the best winter gear doesn't cut it when you're out for extended periods.

I will cut my mileage some when it gets into the 30s, however. Like Crankin, I'm now cross training more and expect to be doing more of other athletic activities that I enjoy when it's too miserable to ride outside. Winter ends and there will be plenty of comfortable riding on dry pavement come spring.