I am having too many of them. The rear 23 year old rim had taken too much braking during commuting. It thinned too much.
The RIM, not the rubber gave up. I had a blowout of epic proportions.
I was doing about five or six on good, clean, flat concrete (thank goodness) when it gave up.
Soon, I would have been doing 20 against the wind down a nice hill.
The blown rim metal caught in the brakes. It would have wrecked me out at 20 mph.
I could not walk it the 12 miles home.
This has not been a good year for my three bicycles.