I know how mine happened: I used to ride out from the back of my house in Georgetown and hop over a chain hung between two posts. Apparently that particular time I was going significantly faster than I usually did and didn't get the front wheel up in time The straight-armed impact was necessary because I was flying out into the street and there was a car coming. I could have tried to roll out of it, but I suspect the secondary injuries from getting run over by a Lexus SUV would have been worse than the broken bones...