Col du Piolet

Overview

Col du Piolet is a genuine hors catégorie effort, and its numbers make no apology for the classification. Over 28.1 km the road climbs from 753 m at the base to a 2470 m summit, delivering 1717 m of net elevation gain. The average gradient sits at 6.12%, a figure that sounds civilised until you register how long you hold it. This is a climb measured in tens of minutes, not a short punch — the sort of ascent where fitness, patience, and fuelling matter more than raw power. At 28.1 km it is among the longest paved climbs you can point a bike at, and the HC label is fully earned by duration as much as by steepness.

How the Gradient Unfolds

The 6.12% average hides real variation. Total ascent registers 1683 m against a net gain of 1717 m, which tells you the climb is very nearly monotonic — there is little to no descending or false-flat give-back along the way. In practical terms, you climb almost every metre you gain. The max gradient of 13.79% is more than double the average, so expect ramps that spike well past what your legs settle into. Between those pitches the road eases back toward the mean, but the relentlessness is the story: from 753 m to 2470 m, the mountain keeps taking. Treat the steep sections as isolated events to survive, not as the new normal, and let the gentler stretches restore your rhythm.

Pacing Notes

On a climb this long, pacing discipline is everything. Anchor your effort to your FTP and hold it steady rather than chasing the gradient. Going too hard on the early kilometres is the classic HC mistake — with 28.1 km ahead, a small overspend compounds badly. Aim to ride the 6.12% sections comfortably below threshold and reserve headroom for the 13.79% ramps, where you will unavoidably surge. If you do not know your threshold, run your recent data through the FTP estimator before you commit to a target. A well-judged effort here is one where your last kilometre near 2470 m feels like your first.

Gearing

Gear for the length, not just the average. With ramps hitting 13.79% after you have already been climbing for a long time, you want spinning room to protect your legs and pacing. A compact 34-tooth inner paired with a wide cassette is the sensible baseline: 34×32 will get most fit riders up the sustained 6.12% grades, but on a 1717 m ascent with double-digit pitches, 34×34 is the smarter insurance. The extra sprocket keeps your cadence up on the steepest metres and preserves your ability to pace rather than grind. If your setup allows anything easier still, no one summiting Piolet will judge you for it.

Summary

Col du Piolet is a long, steady, unrelenting HC climb: nearly no respite, a punishing 13.79% ceiling, and 1717 m of vertical to work through across 28.1 km. Pace it to your threshold, gear generously, and let the mountain come to you.

Length: 28.1 km
Average gradient: 6.12%
Max gradient: 13.79%
Start: 753 m
Summit: 2470 m
Net gain: 1717 m
Total ascent: 1683 m
Category: HC