Saturday 20 July—Stage 20 of the Tour de France is 132.8 kilometres long, and the riders must conquer four mountain tops. The finish is situated at the Col de la Couillole, 15.7 kilometres long and averaging 7.1%.

The penultimate stage of Le Tour.The riders roll out in a northerly direction and enter the first climbs after 15 kilometres. The Col de Braus is a 10-kilometre effort at 6.6%.

Straight after the descent, the road goes back up again. The Col de Turini is the longest climb of the day, at 20.7 kilometres, and it leads to the highest point, 1,608 metres above sea level. The average gradient on the Turini is 5.7%.

The riders fly through the midway marker on the descent and return to the valley. In Roquebillière, the next climb begins at shallow gradients. This part of the Col de la Colmaine is not classified as a climb, but it does go up. Only the last 7.5 kilometres—at 7.1%—are KOM classified, but if you count from bottom to top, the Colmaine is roughly 20 kilometres long and averaging almost 5%.

Following the downhill to Saint-Sauveur-sur-Tinée, the finish climb kicks in. The Col de la Couillole is a 15.7-kilometre ascent with an average gradient of 7.1%.


Climbing Defined by the Number

You’re either going up, down or flat when you’re riding.

For every 100 feet, you go forward, you will also travel vertically for a certain number of feet.

You’ve got your grade if you put a percentage sign after that vertical distance.

For example, suppose you go up two feet as you go forward 100 feet. That’s a 2% grade. Suppose you climb eight feet as you go forward 100 feet. That’s an 8% gradient.

If you want to determine the status of climbs by the numbers, we can look at the classification system used in most professional races.  That would mean climbs are classified as 4, 3, 2, 1 (and Hors Categorie or “HC” in the Tour de France.)  This determination is made by a combination of length in kilometres and average gradient, with the position of the climb in the route and the degree of road surface being lesser determinants.  See below:

  • Category 4 – the lowest category, climbs of 200-500 feet (70-150m). Length is usually less than 2 miles (3km)
  • Category 3 – climbs of 500-1600 feet (150-500m), between 2 and 3 miles (3km and 4.5km) in length.
  • Category 2 – climbs of 1600-2700 feet (500-800m), between 3 and 6 miles (4.5km and 10km) in length.
  • Category 1 – climbs of 2700-5000 feet (800-1500m), between 6 and 12 miles (10km and 20km) in length.
  • Hors Category (HC) – the hardest climbs of 5000+ feet (1500m+). Usually more than 12 miles (20km) in length

As for gradients, typically, the average gradient has to be above 4% to classify a climb.  Hors Category (HC) generally climbs on average of>10% or has an extreme length at a slightly lesser grade.

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