The last big challenge of the 99th Tour de France is an individual time trial that comes after 3,314.5 kilometres of competition. Baring disaster, we effectively know who the winner of the 2012 ‘maillot jaune' is going to be but there's many other tests taking place on the roads between Bonneval and Chartres and much of it relates to the future. Can the two Frenchmen in the top 10, Pierre Rolland and Thibaut Pinot – limit their losses in a discipline that they haven't excelled in before? Can Jurgen van den Broeck hold on to his fourth overall and eclipse what his fifth place from 2010? Will Cadel Evans actually be the best placed of the BMC team or will Tejay van Garderen win the white jersey by being better than last year's yellow jersey winner?
Another critical question will be answered in the 19th stage: is Bradley Wiggins really better than his super-domestique Christopher Froome? The rider in the yellow jersey won the first long time trial but can he win the second?
We'll have all the answers on Saturday evening. And then comes the parade to Paris.