Col des Charbonniers

Overview

Col des Charbonniers is a Category 1 climb in France, running 7.8 km from a valley floor at 445 m to a summit at 1131 m. Over that distance it delivers 686 m of net elevation gain at an average gradient of 8.8%. That combination — under 8 km long but nearly 700 m of vertical — puts it firmly in the "short but severe" bracket, where there is little room to hide and the clock rewards riders who commit early.

The number worth flagging is the gap between net gain and total ascent. You climb 686 m net, but the road actually forces 811 m of ascent — 125 m of extra climbing swallowed by dips and false flats along the way. That undulation means the effort is spikier than the 8.8% average suggests: every metre you coast down, you pay back on the next ramp. Treat the total ascent, not the net gain, as the real workload.

How the Gradient Unfolds

An 8.8% average on an undulating road is misleading. The dips that create the 125 m of extra ascent drag the mean down, which means the climbing sections between them are steeper than 8.8% — often meaningfully so. Expect the gradient to swing rather than hold steady.

• Short flatter or gently descending sections that offer brief recovery, then hand the elevation straight back
• Repeated stacked ramps rather than one continuous wall, so the climb reads as several efforts in sequence
• The steepest pitch punching well into double digits, demanding a hard change of pace and your lowest gear

Pacing Notes

On a smooth climb you can hold a single sustainable power output and let speed take care of itself. Charbonniers does not allow that. Because the grade constantly breaks and re-forms, even-effort pacing beats even-speed pacing: hold a steady power target and accept that your speed will surge on the shallow bits and collapse on the ramps. Chasing a fixed speed here will send you into the red on every steep pitch and leave nothing for the next one.

Set your target before you start. Use the FTP estimator to fix a realistic ceiling, then ride the climb a notch under it so the repeated ramps do not stack fatigue faster than you can clear it.

Gearing

Gearing is governed by the steepest ramp, not the average. On a climb this steep and this spiky, run a compact or sub-compact chainset paired with a wide-range cassette — think 34×32 or 34×34 — so you keep a spinnable cadence when the grade jumps. Grinding a big gear over these ramps will cook your legs long before the summit. Check your chainset and cassette before the ride; the day of the climb is the wrong time to discover you are over-geared.

Summary

• Length: 7.8 km
• Average gradient: 8.8%
• Maximum gradient: 24.14%
• Net elevation gain: 686 m
• Total ascent: 811 m
• Category: 1

Col des Charbonniers is a compact Category 1 test that climbs harder than its length or average gradient advertises. Respect the total ascent, pace to a steady power target, gear low, and it becomes a climb you can ride well rather than merely survive.