In reply to adventure_vulture:
Had this myself about 2 years ago. I was 'luckily' at a standstill and just moving off to cross a road. I ended up on the floor with a the couple of bruised ribs from the handlebar. Since I was at a junction when it happened I can draw some solace from the fact that I gave about 50 drivers and a tram fill of commuters a good laugh.
The bike was quite old, but not 'that' old. Put it down to bad luck, basically.
Bizarrely, I'd witnessed it happen to someone else who was cycling in front of me about 2 weeks previously.
I really do dread to think what would have happened if I'd been moving, at a busy bit of road.