Originally Posted by
BobbyG
But in my opinion the dryness and apparent brittleness of the tube leads me to think it just let go.
This happened on my wife's bike, about a year and a half after she got it. My (heavier) kid was riding it on gravel and it blew out like that (under conditions I might expect a pinch-flat). I have no idea why it blew out like that. There was no evidence of any tire damage (and I have since put that tire on my bike, just in case).