I finally gave up on commuting by bike regardless one day when there was a good 6 inches of very heavy wet snow. I was having to pedal hard to go DOWN hills, and I had to walk the bike up the hills. I got about 2 miles from home, said "what the F am I doing?" turned around and went home and drove.

These days I commute maybe 3 days a week in the winter. So far I've lucked out and I'm still riding the road bike, the roads are still dry.