Col des Portes du Soleil

Overview

The Col des Portes du Soleil is a hors catégorie (HC) climb, the hardest rung on the classification ladder above categories 1 through 4. Over 19.4 km it lifts you from a valley floor at 413 m to a summit of 1953 m — a net gain of 1540 m, with 1522 m of total ascent once the small dips are counted. The average gradient sits at a punishing 7.92%, and at its steepest the road pitches to 25.51%. This is a long, sustained effort with a genuine sting: nearly twenty kilometres where you rarely get to coast, capped by ramps steep enough to force you out of the saddle whether you want to be there or not.

How the Gradient Unfolds

An average of 7.92% across 19.4 km tells you the climb almost never relents. But averages hide the character. The gap between the 7.92% mean and the 25.51% maximum is enormous — more than 17 percentage points — which means the road is not uniform. Expect long stretches close to the average punctuated by sharp, lung-emptying pitches where the gradient more than triples. With 1522 m of total ascent against 1540 m of net gain, the profile is overwhelmingly one-directional: only a small amount of that 1540 m is given back and reclaimed. In practice, you climb, and you keep climbing, all the way to 1953 m.

Pacing Notes

On a climb this long, discipline early pays dividends late. The single biggest mistake is treating the opening kilometres like the 25.51% ramps — you cannot. Anchor your effort to your sustainable threshold. Riding just below your FTP for the bulk of the 19.4 km, then allowing brief surges above it only on the steepest pitches, is the classic HC strategy. If you do not know your number, the FTP estimator will get you a working figure to plan around. Budget for an effort measured in tens of minutes, not seconds, and keep something in reserve for the max-gradient sections — they will spike your power involuntarily, so leave headroom.

Gearing

With 1540 m to gain and pitches touching 25.51%, gear low and gear again. A compact 34-tooth inner chainring is the sensible baseline. Paired with a 34×32, most fit riders can spin a respectable cadence across the 7.92% average, but the 25.51% ramps will still bite hard. For the extra insurance — and on a 19.4 km HC climb the insurance is worth it — step up to a 34×34, which gives you a 1:1 ratio and a meaningful cushion on the steepest sections. If your legs are fresh you may barely touch the lowest sprocket; if they are not, you will be grateful it is there.

Summary

The Col des Portes du Soleil is a proper HC test: long, relentless, and topped by ramps that redline your effort. Pace it below threshold, gear low, and respect the full 1540 m to the summit.

Length: 19.4 km
Average gradient: 7.92%
Max gradient: 25.51%
Start: 413 m
Summit: 1953 m
Net gain: 1540 m
Total ascent: 1522 m
Category: HC