Col d'Arrémoulit

Overview

Col d'Arrémoulit is one of those climbs where the numbers alone tell you to be afraid. Over just 11 km the road averages 10.62%, a figure most riders associate with short, savage ramps — not a sustained mountain ascent that keeps going for the better part of an hour. You start at 1279 m and finish at 2451 m, a summit high enough that the thin air adds its own tax on top of the pitch. With a net elevation gain of 1172 m across those 11 km, this is a genuine hors catégorie effort: the hardest tier there is, above categories 1, 2, 3 and 4.

How the Gradient Unfolds

The headline here is relentlessness. A 10.62% average over 11 km means there is no long false-flat or valley section hiding in the profile to soften the arithmetic — the gradient stays high from bottom to top. Look closely at the two elevation figures and a small clue emerges: the net gain is 1172 m, but the total ascent measures 1087 m, a difference of 85 m. That gap tells you the profile isn't a perfectly clean staircase; there's a little give-and-take in the road. But 85 m spread across 11 km is a rounding error against the overall trend. Treat this climb as one long, near-uniform wall rather than a series of distinct steps, and you'll pace it correctly.

Pacing Notes

On a climb this steep and this long, pacing discipline is everything. A sustainable target is a fraction below your FTP — the power you can hold for roughly an hour. At an average of 10.62%, even a small surge above threshold torches your legs quickly, and there's no flat recovery to bail you out. If you don't already have a reliable threshold number, run the FTP estimator before you commit to a plan, then ride the first few kilometres deliberately conservatively. The 2451 m summit means the final stretch will feel harder than the same watts lower down; keep a little in reserve for the altitude.

Gearing

Do not under-gear this one. An average of 10.62% sustained for 11 km punishes anyone spinning out of climbing gears. A compact 34-tooth chainring paired with a 34×32 cassette is the sensible minimum, and most riders will be far happier with 34×34 to keep cadence up when the road bites. If your setup allows an even easier ratio than 34×34, use it — on an HC climb rising 1172 m, protecting your knees and your cadence matters more than pride.

Summary

Col d'Arrémoulit is a pure test of sustained climbing: no tricks, no relief, just 11 km of steep road to a high summit. Pace it below threshold, gear it generously, and respect the altitude at the top.

Length: 11 km
Average gradient: 10.62%
Max gradient: n/a
Start: 1279 m
Summit: 2451 m
Net gain: 1172 m
Total ascent: 1087 m
Category: HC