90k biking and a flat tire

First time I made the half of the whole Ironman-Strecke. It goes two rounds so that I now know the whole course. The "hill" in the middle called "Pfannenstil" is really a huge piece of work. I was impressed. However, on the way back from Forch to Küssnacht I got a flat tire. Luckily not in a race and nothing happened, though I went quite fast downhill. "Pffffffffffffffffff", T-IM