I run a dedicated winter bike with a very simple set-up.
Rigid mountain bike with nokian studded tires, fenders and to make it even more simple it is a single speed coaster brake.
I don't have to worry about brake lines, pads freezing or gear issues, lines freezing etc.
In the Dakota's it can get sub zero temps with black ice, snow storms, hail you name it...
I also have a rack trunk with extra clothes, etc and run plenty of lights.
With my simple set-up I actually enjoy winter cycling. I am pedaling along while cars won't start, getting stuck and having trouble getting up hills.
My commute time does take twice as long but it is a good workout.