I was about halfway into a 50 mile ride (out and back) and I flatted. Got enough air in the tire to get to a nearby gas station, where I sat down to figure out the extent of the problem. No holes that I could find, but it still wasn't holding air. Tried pumping it up more. BOOM. Exploded at base of valve stem. Changed tubes. Stupid mini pump broke the valve tip off that tube. I was out of tubes. I called a friend, and waited an hour for him to show up.