Tires were Bontrager Race Lites. Very light tires indeed!

I had filled the tires to 120 psi (max pressure) just prior to the ride, so I'm sure the pressure was fine.

Dunno, there was a lot of glass on Dumbarton Bridge -- one of the ladies in our group got a flat. Perhaps a piece of glass/debris worked its way into the tire and caused the blowout....