Ok, I'm on this supported cross-country tour and I come across these two other people on the ride, one of whom has a flat. So the three of us try to fix it ... can't do it, every-time we pump it up it goes flat again. Now it turns out one of these guys had a Ph.D. in nuclear physics, one in EE, and mine is in statistics. So three Ph.D.s and we can't fix a flat and he had to wait for the SAG. How embarrassing. In our defense, it turns out the wheel had a defective rim that was causing the problem, but still.