Originally Posted by 2manybikes
What was the temperature?
If the air temperature is below freezing, and if you are riding on a main road with some traffic. This happens....
I had a bike with new fenders and knobby tires. I hit the fender with my toe and pushed the fender into the tire, same result.
It was +7C. Terrible weather really. I've had a bunch of Presta valves seperate from the tube in cold weather though. One was while I was sitting in the LBS talking to the wrench. The bike had been sitting against the wall for about 45 minutes. We just looked at each other really surprised. It was quite cold that day.
I think you're on to something with the toe theory. I was wearing big boots today, and turning with one foot out of my rat trap. Didn't think of that.