Last summer I had a blow out on a front Michelin tube / PR3 that had been mounted on Fulcrum Race 3 wheels for weeks. It was about 20 miles into a ride; 100 PSI when I started, temperature 85 - 90 degrees, flat smooth pavement, at about 21 mph.

It sounded like a gunshot, which wasn't too funny since I was on the MUP in South Chicago - people around me actually ducked to the ground. There was a ragged hole about 4" long by about 1/4 of the circumference of the tube at what I think had been against the side of the tire. The tube was literally shredded, with little flakes of rubber falling out of the tire when I removed them from the rim. The tire was fine.

I really don't think that it was a pinch flat from the tire slowly going down or I would have had a heck of a time keeping that pace before it went. I never could figure out a violent failure like that. I've never one like it before or since, but I think about it to this day when on fast descents.

Do any of the bike gurus have a suggestion as to the cause on that one?