I've been commuting to work almost every day (every work day, anyway) since I moved to San Francisco in December. I've taken the bus about 3 or 4 times, because of weather or whatever, but other than that I've done 5.5 miles each way every day on the bike.
What I wanted to mention is that my bike hasn't given me a single problem the whole time. I haven't done any maintenance at all, except to add some air to the tires once in a while... until yesterday. I was involved in a sort of panic stop that involved my skidding down the road (upright -- the bike was on its wheels and moving forward, it's just that the real wheel wasn't turning). Anyway, the stop turned out ok and I didn't hit anyone or anything, but I thought "wow, I wonder if I ruined my tire in that skid," so for the first time in months, I looked over my rear tire. This is what it looks like:
Those are three separate holes through the outer part of my tire, and I think only one (probably the biggest one) was caused by my skid yesterday. I've been riding around like that for probably weeks without even noticing. I'm almost surprised those tires still hold 110PSI of air.
Anyway, I bought some new tires today (Michelin Lithions) and I'll be installing them tonight. I hope they give me as long of a maintenance-free streak as the last ones.