Before my ride today, I noticed my rear tire had deflated. That's the second rear flat in as many days. The first one: The rubber around the valve stem had separated. No sharp edges in the hole in the rim, as far as I can tell. The tube was a year old, and DBF suggested I try to be consistent in my use of the little nut thing that comes with them. Okay, one I can live with.

The second one...I found a hole in the tube. Only one, and I hadn't ridden over anything sharp. No corresponding holes in the tire. It was along a seam on the "inside" of the tube, so the only thing I can think of is that it was a bad tube and the seam split overnight.

Those used both my spares. I picked up some new ones on my way home from my ride...after having kept my fingers crossed the whole way.