Stage nineteen: Saturday July 21, Bonneval-Chartres, 53.5km

The deciding stage? If Wiggins and Evans remain closely matched after eighteen stages, this flat, individual test in the Beauce region of France will decide the winner of the 2012 Tour de France.

The inhabitants of Bonneval at the head of the canton of Eure-et-Loir, are used to the sight of cyclists, if not those competing in the Tour de France. Paris-Tours is a frequent visitor to this small town of 4,500 people, but Le Grande Boucle has been here only once, in 2004, when Stuart O’Grady led home a breakaway and Thomas Voeckler pulled on a yellow jersey for the first time.

Neither is expected to feature on the race’s return to Chartres, but Tony Martin, Fabian Cancellara, Dave Zabriskie and other time trial specialists will. Could Tejay Van Garderen seal a bid for the white jersey here?

Among the contenders for overall victory, Bradley Wiggins is arguably the finest against the clock. His track background (six Olympic medals are now almost a footnote to his career) and formidable form this season in the race of truth (time trial victories in the Volta ao Algarve, Paris-Nice, the Tour of Romandie, and the Criterium du Dauphine) will seal his victory if things have gone well in the mountains, or offer him a final card to play if plans have gone awry.