Nice ride in at 39F ( 4C). Yesterday, going home two teeth from hightest gear on the rear cassette broke off. Traffic was heavy in one area, and who knows why, but usually, I either hit that circle going up, or stop at the begining to yield to others, but with cars backed up into the circle I got stuck in the middle and I was still in high gear. The circle goes up hill at that point, and the cars took off a bit quicker than I anticipated, so I pushed down and knew right away what I did. I am on my MTB, which is a favorite for the rest of the week.