Col des Mines

Overview

Col des Mines is a hors catégorie (HC) climb, the hardest rating on the road, and it earns the label without any statistical padding. Over 22.4 km it averages 8.25%, dragging you from a start elevation of 470 m all the way to a 2320 m summit. That is 1850 m of net elevation gain, with a total ascent of 1817 m once the small undulations are accounted for. Nothing about the shape here offers an easy way in: this is a long, sustained, high-altitude ascent that rewards patience far more than power.

How the Gradient Unfolds

An 8.25% average across 22.4 km tells you most of the story before you turn a pedal. There is no gentle valley approach to hide behind and no false-flat middle to spin through — the climb simply keeps taking. The steepest recorded pitch is 14.59%, which is roughly 6.34% above the average, so the hardest ramps land well into double figures while the softer stretches still sit near the mean rather than dropping to recovery gradients.

Because start and summit are separated by 1850 m of net gain over 1817 m of measured ascent, the profile is overwhelmingly one-directional: you climb, and you keep climbing. The thin air of the final approach to 2320 m compounds the arithmetic, so effort that felt sustainable near 470 m grows heavier the higher you go.

Pacing Notes

Treat Col des Mines as a threshold-management exercise, not a series of attacks. On a climb this long, riding just above your sustainable ceiling for the first few kilometres will cost you far more time later than any early gains are worth. Anchor your effort to your FTP and aim to sit comfortably below it on the average sections, leaving headroom for the 14.59% ramps where your speed drops and torque demand spikes.

If you do not have a recent number to ride to, spend a few minutes with the FTP estimator before you commit — a realistic target turns a 22.4 km climb from a survival exercise into a controlled one. Meter the steep pitches, then settle straight back to your rhythm rather than trying to "make up" the slower metres.

Gearing

At 8.25% average with ramps to 14.59% over 22.4 km, gear low and gear early. A compact 34-tooth chainring paired with a wide cassette is the right foundation. A 34×32 will get most fit riders up the average gradient at a workable cadence, but on a climb this sustained — and this high, finishing at 2320 m — a 34×34 is the smarter insurance, giving you a spinning gear for the 14.59% sections when your legs are already deep into 1850 m of gain. If your bike can take a larger cassette still, there is no shame in it on an HC ascent.

Summary

Col des Mines is a genuine HC test: long, relentless, and high. Pace it to your threshold, gear generously, and respect the altitude, and its 1850 m of net gain becomes a climb to savour rather than merely endure.

Length: 22.4 km
Average gradient: 8.25%
Max gradient: 14.59%
Start: 470 m
Summit: 2320 m
Net gain: 1850 m
Total ascent: 1817 m
Category: HC