Col du Passet

Overview

The Col du Passet is a genuine hors catégorie test, the kind of climb that demands respect long before you reach the steepest ramps. Over 18.5 km it averages 8.19%, a figure that rarely lets up and never invites complacency. From a start elevation of 461 m you grind all the way to a 1974 m summit, banking 1513 m of net elevation gain along the way. Factor in the rolling dips and false flats and the total ascent swells to 1576 m — proof that the profile is not a clean, uninterrupted staircase but a climb with texture. At HC, it sits at the very top of the difficulty scale, harder than any categorised climb below it.

How the Gradient Unfolds

An 8.19% average across nearly nineteen kilometres is punishing on its own, but the number that defines the Passet is its 24.06% maximum. A ramp that steep is close to walking-pace territory for most riders, and it means the climb is far from uniform. Expect long sustained stretches hovering around the average, punctuated by pitches that spike well into the teens and, at least once, into the low twenties. The gap between the 1513 m net gain and the 1576 m total ascent tells you there are short reprieves — brief descents or flatter shoulders — but each one only sets up the next wall. This is a climb best broken into mental segments rather than swallowed whole.

Pacing Notes

Discipline wins here. On a climb this long, going out hard on the lower slopes will cost you dearly before the summit. Anchor your effort to your FTP and aim to sit just below threshold on the sustained sections, saving matches for the double-digit ramps where power inevitably surges. The 24.06% pitch will spike your effort no matter how smoothly you ride, so accept the surge, stay seated where traction allows, and settle back down quickly afterward. If you are unsure of your numbers, run them through the FTP estimator before you commit to a target, then hold that ceiling patiently across all 18.5 km.

Gearing

Do not under-gear the Passet. With an 8.19% average sustained for so long and a 24.06% maximum lurking, most riders will want the widest range they can fit. A compact 34-tooth chainring paired with a wide cassette is the sensible baseline: a 34×32 will get many strong climbers over the top, but on the steepest ramps — and after more than 1500 m of climbing in the legs — a 34×34 gives you the extra breathing room to keep spinning rather than grinding to a stall. If your setup allows an even larger sprocket, you will not regret it on a climb that gains 1513 m.

Summary

The Col du Passet is a complete mountain: long, relentlessly steep, and topped off with a brutal maximum pitch. Pace it with humility, gear it generously, and the 1974 m summit is a reward worth every metre of the 1576 m you ascend to reach it.

Length: 18.5 km
Average gradient: 8.19%
Max gradient: 24.06%
Start: 461 m
Summit: 1974 m
Net gain: 1513 m
Total ascent: 1576 m
Category: HC