Col de l'Aiguillon

Overview

Col de l'Aiguillon is a Category 1 climb in France that earns its classification honestly. At 11.9 km long with 991 m of total ascent and an average gradient of 6.48%, it already sits firmly in the serious end of the grading scale. But the number that defines this climb is the maximum gradient: 26.87%. That figure is not a misprint, and it will shape every decision you make about gearing before you even roll to the start.

The climb begins at 509 m elevation and rises to a summit at 1282 m, a net gain that demands sustained power output over a long enough distance to deplete even well-conditioned riders if they go out too hard.

How the Gradient Unfolds

With a 6.48% average across 11.9 km, the expectation might be a manageable, rhythmic grind. Discard that expectation. The 26.87% maximum gradient signals that the road does not distribute its difficulty evenly. Somewhere on this climb — likely concentrated in one or more short, punishing ramp sections — the gradient spikes well beyond double the average. These sections can arrive with little warning and force riders who are already fatigued into the red zone at the worst possible moment.

The contrast between a 6.48% average and a 26.87% peak is roughly 4:1. That spread tells you the climb alternates between passages that allow partial recovery and walls that demand everything. Treat the shallower sections as active recovery, not an invitation to surge.

Pacing Strategy

The length alone — nearly 12 km — means this is a power-management climb, not a punchy effort. If you're familiar with your FTP, use it as your ceiling during the moderate sections. The steep ramps will force you above threshold regardless; burning matches on the runup to them is the most common mistake on climbs with this gradient profile.

Key pacing principles for Col de l'Aiguillon:

• Start conservatively. With 991 m of total ascent ahead, any time saved by going hard in the first third will be paid back with interest on the ramps.
• On ramps approaching or exceeding 20%, shift early. Standing out of the saddle on 26%+ grades is workable for a few seconds; it is not a substitute for a low enough gear ratio.
• Use every shallow passage to bring heart rate down and cadence back to a comfortable range before the next steep section.
• Don't fixate on average speed. On a climb with this gradient variance, speed fluctuates dramatically. Ride to perceived effort and power, not the number on your computer.

Gearing Notes

A 26.87% maximum gradient sets a hard floor on the gearing you need. Compact chainsets (50/34) with an 11-32 or 11-34 cassette are the practical minimum for most riders. If you're running a standard double, a 39-tooth inner ring becomes punishing on walls above 20%, particularly in the final third of an 11.9 km climb when fatigue has already accumulated. Riders on 1x drivetrains should verify their low gear carefully before committing to this ascent — a 40-tooth chainring with a 42-tooth cassette low end is a reasonable baseline.

If you're unsure how your current fitness translates to power output on sustained gradients, the FTP estimator can help you set realistic targets before heading out.

Bottom Line

Col de l'Aiguillon is a Category 1 climb that warrants that designation. The 11.9 km length and 991 m of ascent would make it a significant effort at a steady gradient. The 26.87% maximum turns it into a technical challenge as much as a fitness test. Arrive with appropriate gearing, a conservative opening pace, and no illusions about what the steep sections will ask of you.