As two riders touched, a massive, high-speed pile-up ensued. To give you an idea of the speed involved, last year's stage four winner had and average speed of 40.5 kph.

That crash was captured by racer Jérémy Roy, who miraculously managed to avoid the crush - in his own words - "don't ask me how I did it."

Here's what it looked like from the spectator's view.

Ooof.