Col d'Arratille

Overview

The Col d'Arratille is short on paper and merciless in the legs. Over just 3.4 km it averages a savage 16.76%, lifting you from a start elevation of 1832 m to a summit of 2405 m. That is a net gain of 573 m, with a total ascent of 602 m once the minor undulations are counted. There is no easing-in stretch to hide behind here — the average alone is steeper than the ramps most riders dread on far longer climbs, and it earns its hors catégorie (HC) rating not through length but through sustained, unrelenting steepness at high altitude.

How the Gradient Unfolds

Think of this climb as a wall rather than a road. With a 16.76% average across the full 3.4 km, there is very little variation to break the rhythm — the gradient sits well into double digits from bottom to top. The gap between the 573 m net gain and the 602 m total ascent is small, just 29 m, which tells you the profile barely dips: almost every metre you climb, you keep. Starting already at 1832 m and topping out at 2405 m, the thinning air compounds the effort, so the perceived difficulty climbs faster than the numbers suggest as you approach the summit.

Pacing Notes

On a climb this steep and this short, pacing is about damage control, not negative splits. Your power will naturally spike simply to keep the wheels turning against 16.76%, so the goal is to hold an effort you can sustain to the top rather than blowing apart in the first kilometre. Anchor your effort to your FTP: riders will often be forced above threshold here just to maintain momentum, so know your ceiling before you commit. If you are unsure of your number, run the FTP estimator first and set a realistic target. With only 3.4 km to cover, a steady, slightly-over-threshold grind is usually faster and safer than surging — every acceleration on a 16.76% slope is expensive, and there is no flat to recover on.

Gearing

This is a climb where gearing decides whether you ride it or walk it. A 16.76% average sustained for 3.4 km at over 1832 m of altitude demands the easiest ratios most riders can fit. A compact 34-tooth chainring paired with a 34×32 low gear is the sensible minimum, and many riders will be far happier with 34×34 to keep cadence off the floor. If your bike accepts it, do not hesitate to go easier still — spinning a low gear will always beat grinding to a standstill on slopes this severe. Set your gearing for the steepest sustained section, not the average, and you will preserve your legs for the summit.

Summary

The Col d'Arratille is a pure test of climbing strength: short, savagely steep, and set high in the mountains. Respect the 16.76% average, gear low, and pace to your threshold — do that and its 573 m of vertical will feel earned rather than survived.

Length: 3.4 km
Average gradient: 16.76%
Max gradient: n/a
Start: 1832 m
Summit: 2405 m
Net gain: 573 m
Total ascent: 602 m
Category: HC