Col de la Corne

Overview

The Col de la Corne is a long, honest mountain climb that rewards patience over punch. Over 19.1 km it lifts you from 810 m at the base to a 2030 m summit, a net elevation gain of 1220 m at an average gradient of 6.38%. That places it firmly in category 1 — one rung below the fearsome hors catégorie tier, but harder than any 2, 3 or 4 you will find. The total ascent of 1253 m is slightly more than the net figure, telling you the road does not rise in one clean line; there are small dips and flatter shelves woven into the overall trend upward.

This is not a wall you sprint at. It is a sustained effort measured in tens of minutes, and its difficulty comes from duration as much as steepness. Nearly two vertical kilometres of thin mountain air wait at the top.

How the Gradient Unfolds

A 6.38% average across 19.1 km is deceptive because averages hide texture. The gap between the 1253 m total ascent and the 1220 m net gain — 33 m of extra climbing — means some sections briefly ease or even tip downhill before resuming the fight. Expect stretches noticeably steeper than 6.38% to balance those softer shelves.

Treat the climb as a long, rolling ramp rather than a constant incline. Where the road flattens, resist the urge to surge; where it steepens above the average, hold your effort steady rather than chasing a fixed speed. The summit sits at 2030 m, so the closing kilometres also thin the air, quietly taxing your legs even where the gradient itself relents.

Pacing Notes

On a climb this long, pacing is everything. Anchor your effort to a percentage of your FTP rather than to speed or feel, because feel drifts as fatigue and altitude accumulate. For a sustained category 1 effort near 19.1 km, riding just under threshold keeps you clear of the red until the final push.

If you do not know your threshold number, run your recent data through the FTP estimator before you tackle the Corne. Then hold your chosen zone from the very first ramp — the biggest mistake here is starting too hard on the lower slopes and paying for it across the remaining vertical metres.

Gearing

With 1220 m of net gain stacked into a 6.38% average, you want a bailout gear ready before you need it. A compact chainring paired with a wide cassette is the sensible baseline. A 34×32 will carry most strong riders through the steeper-than-average pitches without forcing you out of the saddle, but on a climb topping out at 2030 m, where late fatigue bites hard, a 34×34 buys you priceless extra cadence.

If you are choosing between them, err toward the 34×34. The Corne is long enough that spinning a lighter gear at a comfortable cadence will beat grinding a heavier one over 19.1 km every time.

Summary

The Col de la Corne is a patient climber's mountain: 19.1 km of steady 6.38% gradient, no gimmicks, just a long haul from 810 m to a 2030 m summit. Pace it to your threshold, gear it generously, and let the numbers do the work.

Length: 19.1 km
Average gradient: 6.38%
Max gradient: n/a
Start: 810 m
Summit: 2030 m
Net gain: 1220 m
Total ascent: 1253 m
Category: 1