The mountainous 2019 edition of the Tour de France will favor the strongest climbers in the peloton. We look at the seven key stages that will decide the yellow jersey winner.

Stage 6: La Planche des Belles Filles (July 11)

On this first summit finish it looks likely some gaps will start to appear in the peloton. This is the race's fourth visit to the summit since 2012, but this time the Tour will go even higher: "The stage also races up a part that we had built up there so that the (publicity) caravan could turn around," says Tour director Christian Prudhomme. "That's an extra kilometre at an average gradient of 9.5%."

Stage 13: Pau - Pau time-trial (July 19)

As the only individual time-trial on the 2019 edition, this 27km loop around Pau is the specialists' only chance to make their mark, while the weaker riders against the clock could be tempted to put too much into it. "It's on rolling terrain with a seven percent gradient hill, not as tough as the one last year, though," says race planner Thierry Gouvenou.

Stage 14: Tarbes - Tourmalet (July 20)

The Tourmalet is the mountain most visited by the Tour de France and first featured in 1910. This year's ascent is on a comparatively short stage of 117km. The final ascent to the summit finish is 19km long at an average of 7.4 percent and was the scene of a classic struggle in the fog in 2010 where Andy Schleck just edged Alberto Contador.

Stage 15: Limoux - Foix Prat d'Albis (July 21)

The final Pyrenean stage will offer a sense of drama given it runs though the ancient ruins of Cathar strongholds and fascinating geological formations and hills so steep that tourists to the region are often seen pushing their cars. The Prat d'Albis, 11.8km at an average gradient of 6.9 %, is a leap into the unknown.

Stage 18: Embrun - Valloire (July 25)

With summits sitting at over 2000 metres in altitude, the great Alpine classics of Vars, Izoard and Galibier speak for themselves. This is the first time the Tour has visited all three mountain passes since 2011. The finish line comes after a very technical descent.

Stage 19: Saint-Jean-de-Maurienne - Tignes (July 26)

The peloton passes over the summit of the Col de L'Iseran, whose summit sits at an impressive 2770m altitude, at the 85km mark with 13km of climbing before a descent into a steep valley. The peloton will then swing past the Tignes dam and start a 7.5km climb before a final, flat kilometre rounds out the stage in the thin mountain air.

Stage 20: Albertville - Val Thorens (July 27)

This stage is as difficult for its descents as it is for the final climb to the summit, over a whopping 33.4km at an average gradient of 5.5 percent. This is the final showdown before a flight to Paris for the 21st stage. It featured once before on the Tour, on a stage won by the Colombian Nelson Rodriguez.