This week the Tour de France route changed when the organisers confirmed that stage 20 would ascend the Croix de Fer instead of the Galibier.
The rest of the sharp ascents and long mountain passes remain, and it is on this inclines that the 2015 yellow jersey will be likely decided.
Here we look at two climbs that could shake up the first week, and two more that could decide the general classification.
Mur de Huy
1.3km, 9.3% average gradient
Stage three will finish on the Mur de Huy, the sharp climb that is the culmination of the spring classic La Fleche Wallonne. This short, steep climb is suited to punchy classics riders like Michal Kwiatowski and Alejandro Valverde. The Spanish rider won here in the 2014 and 2015 editions of La Flèche Wallonne.
Mur de Bretagne
2.21km, 6.5% average gradient
Stage eight of the race will finish on the Mur de Bretagne, a short but tough climb in Brittany. This climb was last used as a stage finish in 2011 when Cadel Evans won on the day and went on to take the overall.
18km, 6.1% average gradient
This climb in the Rhone-Alpes is now best known because of Team Sky's internal leadership battle in 2012, when Chris Froome dropped his team leader, Bradley Wiggins, on the climb before being told by his directeur sportif to slow down. Coming on stage 19 of the 2015 race, its length and gradient favours a measured effort rather than an explosive finish.
13.8km, 8.1% average gradient
Now a regular feature since it first appeared in 1952, Alpe d'Huez has become an iconic part of the Tour. The penultimate day of the 2015 race will be a short stage ending on here as it did 2011, and is a crucial stage in which the Tour de France could be won or lost.
The mountain's trademark 21 hairpin bends have been the site of many classic Tour battles, including in 1986 when Greg LeMond and Bernard Hinault crossed the line together.
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