What a nasty uphill drag at the end. Christian Prudhomme must have been killing himself laughing when he came up with that one. An inspired choice of finish.
There's a story behind that.
The finish of stage 4 is the Mur de Bretagne, which is a lot steeper than most roads in France for the reasons outlined by Graham Robb in his excellent book 'The Discovery of France'.
Quote
"The chief engineer in the Limousin, Pierre Tresaguet, had insisted that a limit should be placed on [road] gradients. ... The old road east of Morlaix still includes a needless climb of 15 per cent (1 in 7) because the blundering military Governor of Brittany, the Duc d'Aiguillon, preferred straight lines to the more accommodating curve of the older road that runs alongside. Thanks in part to Tresaguet, it is unusual now to find a climb in excess of 8 per cent (1 in 12). This was thought to be the steepest gradient that a fully laden mule could manage. British mountain roads seem to rise in fits and starts like step pyramids. French mountain roads go much higher, but more steadily, and can comfortably be climbed for hours by a fully laden cyclist."
"To judge by the army handbook of 1884, it is fortunate that most road building was left to civil engineers:
Gradient on which troops can still march in good order: 25 per cent;
Gradient manageable by mounted horses and light carriages: 33 per cent;
Gradient manageable by mules: 50 per cent;
Escarpment that an infantryman can still cross by using his hands: 100 per cent (completely vertical)"