Col du Chardonnet

Overview

The Col du Chardonnet is an hors catégorie climb that trades length for ferocity. At just 7.7 km it is short by HC standards, but the numbers tell the real story: an average gradient of 13.63% that hauls you from a start elevation of 489 m to a summit of 1533 m. That is a net elevation gain of 1044 m packed into under eight kilometres, with a total ascent of 1012 m once the road's brief undulations are accounted for. There is no easing-in, no valley approach folded into the average — this is a sustained double-digit wall from bottom to top.

How the Gradient Unfolds

An average of 13.63% is punishing, but averages hide the worst of it. With a maximum gradient of 25.08%, the Chardonnet holds ramps more than eleven points steeper than its own mean — pitches that approach a one-in-four incline. Because the climb is so short and so consistently steep, there are few genuine recovery stretches to reset your legs between efforts. Expect the gradient to sit stubbornly in the teens for long sections, punctuated by those savage 25.08% kicks. The 32-metre gap between the 1044 m net gain and the 1012 m total ascent suggests only the slightest respite exists across the whole 7.7 km — the road essentially points up the entire way.

Pacing Notes

On a climb this steep and this short, pacing is about survival, not negotiation. The temptation is to attack the lower slopes, but every over-effort on a 13.63% average compounds fast. Ride to your FTP and resist the urge to chase surges on the 25.08% ramps — let the gradient dictate cadence rather than fighting it with sheer power. If you do not know your threshold, run the numbers through the FTP estimator before you commit to a target. Because the full 1044 m of climbing arrives in one continuous block, plan to bleed a small buffer below threshold early so you have something left when the steepest pitches bite in the final kilometres.

Gearing

Do not under-gear this one. With a 13.63% average and pitches touching 25.08%, most riders will want the easiest cassette they can bolt on. A compact 34-tooth chainring paired with a 34×32 is the realistic minimum for a sustained assault at these gradients, and even strong climbers will be grateful for a 34×34 when the road tilts toward that 25.08% maximum. On a 7.7 km wall gaining 1044 m, the extra sprocket is the difference between spinning and grinding to a standstill — err toward the larger cog.

Summary

The Col du Chardonnet is a compact monster: 7.7 km of relentless, double-digit climbing that earns its hors catégorie badge through gradient rather than distance. Prepare your legs, your gearing, and your pacing before you start — this HC climb does not forgive.

Length: 7.7 km
Average gradient: 13.63%
Max gradient: 25.08%
Start: 489 m
Summit: 1533 m
Net gain: 1044 m
Total ascent: 1012 m
Category: HC