It was my own fault really. A beautiful winter's day, sun dancing on the trees...
My and my buddy decide to try a new trail. We've both slickified our MTBs for the winter training (I'm a roadie, he's a commuter) but we think what the heck, it'll be more fun.
Anyway, we get to the trail and it's a great laugh. Mud everywhere and yet still managable: perfect balance for me.
We finish the trail and are riding home, probably about 5 miles from our house. I notice that my back end is transmitting every slight bump up to my arse, so I look down, and whaddayaknow, I got a slow puncture. Bugger. I ride on for a little while as it is still ridable at this point, but then I succombe to the fact that I'm gonna have to push.
When I get home, I decide to see what caused it. Couldn't see anything so I reinflated it to pinpoint the hole. Nothing. So I completely deflate it and pinch the tyre. Inside the casing is THE smallest piece of brown glass I've ever seen. It can't have measured 1mm x 1mm and it was sooooooooo thin that it was dangerously sharp. I reckon I picked it up when I rode through a park where some kids had been drinking and had thrown their empties on the floor.
So yeah, my own fault I guess. Man I hate under-age drinkers!!!