The return of the rainy season brings an extra hazard for bicycles: Sharp debris from the roadway may cling to the wet tire for a couple of revolutions, giving little bits more than one chance to cause trouble.
This morning at about 6.30am I picked up a piece of glass a little smaller than a paper match-head in my rear tire, and that was enough to bring the commute process to a near-standstill.
I should explain, though, it was a Continental Ultra Gator Skin tire, purchased in August 2007, and it had about 4700 miles on it, which ain't shabby but is also past the recommended usage time. (CUGSs are almost too good; I just about never get a flat, so I don't carry my patch kit with me like I should. Tsk.)