What are difficulty points?

Every ascent on climbfinder has difficulty points. This number indicates how much effort it takes to to reach the top of a climb. With the difficulty points, climbs can therefore easily be compared with each other. If you want to brag, it can now only be done in climbing points!

Length and steepness together make a climb difficult
Length and steepness together make a climb difficult

Comparing climbs which each other is always a matter of discussion. Although almost nothing changes in the physical properties, the same ascent feels slightly different every time. Sometimes it's the wind, sometimes the shape of the day and almost always it's all in the head. For many cyclists, an ascent is as difficult as the last time he or she rode up. In addition to these subjective differences, a couple of crucial factors play a role in the difficulty of an ascent. The gradient, the length and the road surface are the most important factors.

Encyclopedia Cotacol

Our formula for calculating difficulty points is based on the legendary Encyclopedia Cotacol from the 1980s, in which all slopes in Belgium were compared. Two avid cyclists rode all over Belgium to make detailed elevation profiles of all ascents. They also came up with a sophisticated formula that calculated the difficulty over the entire course of an ascent. The Encyclopedia Cotacol has now become a standard work and the formula is widely used in other books and websites.

Steep sections are exponentially more difficult

The cotacol formula does not look at the average gradient of an ascent, but divides it into 100-meter sections. The formula then assigns each section difficulty points. By doing this, the approach takes into account the often erratic pattern of climbs. Steep sections get exponentially more points, because it becomes exponentially more difficult to ride 100 meters if it gets more steeper. For example, an smooth ascent scores relatively less climbing points than a climb with a steeper section, even if they have the same height difference.

Two short climbs with equal meters ascent have completely different difficulty points due to the structure
Two short climbs with equal meters ascent have completely different difficulty points due to the structure

Extreme accuracy

Nowadays thousands of recordings by bike computer (with altimeters) have been made of each climb in Europe. In addition, geographical data with extreme accuracy (LIDAR) is available. This makes it possible to apply the formula even better. For example, we can now cut climbs into pieces of just 25 meters, which makes the calculation even more accurate than was possible during the making of the Encyclopedia Cotacol.

Compare climbs

Not only does the formula work well on short climbs like you find in Belgium, difficulty points are also perfect for comparing climbs in the Alps. In fact, we love it so much, that we also use it to calculate the climb categories.

Although the number of difficulty points is perfect for comparing climbs in the same region, you could also perfectly compare the Alpe d'Huez with the super steep cobblestone climb Koppenberg. The number of climbing points indicates the total effort it takes to reach the top of a climb, where the total duration of the effort ensures that the Alpe d'Huez will get many more climbing points. However, there will be more people thinking of getting off the bike on the short steep section of the Koppenberg, but that one moment does not mean that it takes more effort to cycle the Koppenberg than the Alpe d'Huez.

Martijn

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Comments (2)

viz
1 Mo

Will you share the formula for calculating difficulty points? I would really like to know how you calculate it. Perhaps it would also be nice to make a calculator where people can enter the details of a climb and get back a difficulty score, i.e. it allows you to map the elevation for every 100 m and then it calculates the difficulty of the climb.
Would also be more helpful for you for people who submit new climbs if they do these calculations themselves.

Martijn
1 Mo

H Viz. The formula is quite easy. For each segment of the climb (for example each 100m, but it could be each 10m as well to make it more precise) you do: (gradient * gradient) * 0.1 . If the segment has cobbles the result is multiplied by 1.7.

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