Col du Grapillon

Overview

Col du Grapillon is an HC (hors catégorie) climb in France, rising over 12.6 km from a start elevation of 510 m to a summit at 1,532 m. That gives a net elevation gain of 1,022 m at an average gradient of 8.08% — enough sustained pitch to put this firmly in the top tier of categorized ascents. It is a long, serious effort, the kind that rewards a rider who knows their numbers going in.

The headline figure to watch is not the net gain but the total ascent of 1,829 m. Subtract the net gain and you are left with 807 m of extra climbing that does not show up in the point-to-point elevation change. That gap means the road undulates: it climbs, gives some of it back, then climbs again. Every metre you descend mid-climb is a metre you re-earn, so the actual work is meaningfully harder than the 8.08% average suggests.

How the Gradient Unfolds

An 8.08% average is a blend, not a constant. On a climb with 807 m of hidden ascent, that average is pulled down by descending and flatter stretches and propped up by ramps far steeper than the mean. The steepest recorded pitch hits 34.52% — a wall you cannot ride at tempo. Plan for the profile to swing rather than settle.

• Recovery breaks where the road flattens or drops, letting you spin and eat
• Repeated short climbs that stack up to the 1,829 m total ascent
• A brutal maximum ramp of 34.52% that demands your lowest gear and a standing effort

Pacing Notes

On an undulating climb like this, chase even effort, not even speed. Your pace will look ragged — fast on the flatter recovery bands, crawling on the ramps — but your power and heart rate should stay in a controllable window. Anchor that window to your sustainable power output and hold below it on the mid-climb dips so you have headroom left for the 34.52% wall. Overcooking the early ramps is the classic Grapillon mistake. If you do not know your threshold, run the FTP estimator before you plan pacing bands.

Gearing

The 34.52% maximum gradient dictates your setup, full stop. No amount of fitness saves you if the gear is too tall — you will grind to a halt. Run a compact or sub-compact chainset and pair it with a wide-range cassette, something like a 34×32 or 34×34 at minimum. On the steepest pitches you want cadence, not muscle. Check your drivetrain and confirm your smallest gear before the ride, not at the base of the wall.

Summary

• Length: 12.6 km
• Average gradient: 8.08%
• Maximum gradient: 34.52%
• Net elevation gain: 1,022 m
• Total ascent: 1,829 m
• Category: HC

Col du Grapillon is harder than its average implies. Respect the 807 m of hidden climbing, gear for the wall, and pace to effort — do that, and the summit at 1,532 m is yours.