Big time gaps, crazy fans and unzipped jerseys are sure to accompany all who attempt to tackle the following climbs. And any cyclist who reaches the summit first will go down in cycling lore as one of the greats.
Alpe d'Huez1 of 6
Average gradient: 8.1%
A Tour staple, all cyclists who ride into Paris have to reach the summit of this infamous climb first. Alpe d'Huez contains a grueling 21 switchbacks and tops out at 10,930 feet. The numerous switchbacks make this climb cycling's biggest arena and rowdiest atmosphere, with gobs of spectators—usually numbering in the hundreds of thousands—lining the streets to cheer on the competitors.
Mount Ventoux2 of 6
Distance: 21.4 km
Average gradient: 7.6%
When cyclists break through the tree line at over a mile high, it spells nothing but misery to the climb's summit, as cyclists have to tackle not only the steep gradient but also extreme winds. Similar to Alpe d'Huez, this has become a favorite summit for stage finishes and the barren, moon-like landscape has become unmistakable to cycling fans.
Col du Tourmalet3 of 6
Average gradient: 7.3%
The Tour's most-used climb, the Col du Tourmalet contains the highest paved road in the Pyrenees and is a right of passage for any Tour de France rider. While the summit is rarely used for stage finishes, the 6,500-foot ascent is as brutal as any on the Tour. Perhaps the reason for the climb's frequency is due to its versatility; race organizers have used both the eastern and western sides of the mountain as ascents when deciding on a route.
Col du Galibier4 of 6
Average gradient: 5.5%
While not the steepest of climbs, the Col du Galibier wears cyclists down by its sheer length. A seemingly never-ending climb with long, straight roads it's usually part of a mammoth stage that also includes the Col du Telegraphe (when coming from the north) or the Col du Lauteret (when coming from the south). The climb's summit is also 8,678 feet above sea level, making it the second highest point on the Tour, behind Alpe d'Huez.
Col d'Aubisque5 of 6
Average gradient: 7.2%
In 1910, eventual Tour winner Octave Lapize famously called the race organizers assassins as he walked his bike up much of this steep climb. And, in 1926 a dozen cyclists secretly crested the Col d'Aubisque by bus. These instances contain everything you need to know about this climb, which is the second-most traversed in Tour history.