I used to commute on a single speed but I found it too limiting in terms of speed on both ends. Climbing the bridge in the morning on a bad day was difficult and top speed was limited as well unless you want to pedal like a hummingbird. Then I had a Shimano 4-speed internal hub, that was perfect, until it broke So I'm back to regular gears. I just carry a small brush with me and wipe the drivetrain after each messy ride, then I have less cleaning to do later. I replace cables in Spring anyway, if Winter was messy, so that doesn't bug me.

Adam