Burst Tyre

BillB fair point. but I thought Mavic open-pros were fairly decent rims. its not like I'm having a catalogue of tyre failiures, I just want to know why this one went so It doesn't happen again for the same reason.

Yeah, they are. I was speaking more generally. My guess, like a lot of the preceding posters, is that it was the tube/tyre interface. Probably won't happen again for a long time.... fingers crossed.... ;-)