The final mountain stage of the 2010 Tour de France was already designed to be incredibly challenging, with 3 high mountain passes in the Pyrenees, each one harder than the last. Add in the fact that the top two riders in the race were separated by only 8 seconds at the start of the day, and Stage 17 became one of the hardest rides the Tour has ever seen. Exactly how hard is that? Read on to find out!