This was published recently...
http://www.bbc.co.uk/sport/0/cycling/30507188
So it was 47mph crash, just hit something on the road (which had looked clear) whilst reaching for something to eat...
At that moment, I relaxed, I looked ahead, saw the road was clear and reached back into my pocket to get something to eat. That's when I hit something in the road, my bike jumped and I lost control.
The problem wasn't the pain from my tibia, it was the thought that I was in great form but couldn't carry on.
When I think I was going 77kmph at the time and I only broke my tibia, well, on balance, that's good. Maybe I lost the Tour, but I didn't lose my life.
My takeaway would be that at that kind of speed you just can't see far enough ahead to let go of the controls.