Col du Croix

Overview

Col du Croix is a hors catégorie climb, the hardest rung on the ladder above categories 1 through 4, and it earns the label the honest way. Over 16 km the road averages 8.84%, a figure that leaves almost nowhere to recover. You start at 389 m and top out at 1802 m, a net gain of 1413 m, with the cumulative ascent tallying 1379 m once the small dips and false flats are accounted for. This is not a climb you talk your way over. It is one you meter out, kilometre by kilometre, and respect from the first pedal stroke.

How the Gradient Unfolds

An 8.84% average across 16 km is punishing precisely because it is relentless rather than spiky. Sustain the mean and you are climbing at roughly the same effort for the better part of an hour. But the average hides the sting: the gradient spikes as high as 23.76%, nearly triple the mean. That maximum is where cadence collapses and where riders who spent too freely earlier pay in full. Expect the pitch to swing well above and below 8.84% in waves, so treat the average as a budget rather than a promise. The gap between the 1413 m net gain and the 1379 m total ascent tells you the ramps dominate and genuine respite is scarce.

Pacing Notes

The single biggest mistake on a climb like this is starting above your sustainable ceiling. Anchor your effort to your FTP and hold something in reserve for the 23.76% ramps, where power spikes regardless of intent. On the steepest pitches your speed drops so low that momentum stops helping you, so smooth, even torque beats surges. If you are unsure of your threshold, run the numbers through the FTP estimator before you commit to a target. For 16 km of near-continuous 8.84%, most riders are best served pacing just under threshold on the flatter sections and letting the pitch push them briefly over on the walls, then settling straight back.

Gearing

Gear for the maximum, not the average. At 23.76% even strong riders need a bailout ratio, so bring more range than you think. A 34×32 is the sensible floor here and will get most fit riders up the sustained 8.84% sections, but on the 23.76% ramps it can leave you grinding a cadence low enough to threaten traction and knees alike. If your legs are not race-fresh, a 34×34 buys you the extra spin that keeps the pedals turning through the worst of it. Given 16 km at this average with a summit at 1802 m, err toward the easier 34×34 — you will never regret the spare gear on an HC climb.

Summary

Col du Croix is a genuine HC test: long, steep, and unforgiving from 389 m to 1802 m. Pace it against your threshold, gear conservatively for the 23.76% walls, and treat the 8.84% average as a ceiling to sit just beneath. Do that and 1413 m of gain becomes an accomplishment rather than an ambush.

Length: 16 km
Average gradient: 8.84%
Max gradient: 23.76%
Start: 389 m
Summit: 1802 m
Net gain: 1413 m
Total ascent: 1379 m
Category: HC