Col de Crête Sèche

Overview

Col de Crête Sèche is an hors catégorie climb — the hardest rating there is, sitting above categories 1 through 4 — and its numbers explain why. Over 25.7 km the road lifts you from 555 m at the base to a 2088 m summit, a net gain of 1533 m. The average gradient reads a relatively civil 5.96%, but averages lie on a climb this long: buried inside is a max pitch of 33.44%, a wall steep enough to stall all but the freshest legs. This is a full afternoon of climbing, not a quick effort, and it demands respect from the first pedal stroke.

How the Gradient Unfolds

At 25.7 km, Crête Sèche is defined by its length as much as its slope. A 5.96% average across that distance means long stretches of steady, grinding work rather than one sustained wall. But the gap between the 5.96% average and the 33.44% maximum tells the real story: the climb is uneven. For every gentle section that lets you breathe, there is a sharper ramp waiting to claw back the difference. The 33.44% pitch is an outlier — a brutal spike you must survive rather than race. Because total ascent (1512 m) sits just under the net gain (1533 m), the road climbs almost relentlessly upward with little relief, so plan your effort assuming you rarely get to coast.

Pacing Notes

On a climb this long, pacing is everything. Your goal is to hold an effort you can sustain for the full 25.7 km without blowing up on the steep ramps. Anchor your intensity to your FTP — riding steadily below threshold on the shallow sections buys you the headroom to survive the 33.44% spike without going deep into the red. If you do not know your threshold, run the numbers through the FTP estimator before you start, then ride the early kilometres conservatively. The riders who reach 2088 m in good shape are the ones who left something in reserve for the wall.

Gearing

With a max gradient of 33.44% and 1533 m of climbing to absorb, gear low and gear early. A compact 34-tooth chainring is the sensible front choice, but the cassette is where you win or lose the day. A 34×32 works for strong climbers who can turn a bigger gear on the shallower average of 5.96%, yet on the 33.44% ramp even that can feel geared out. If you have any doubt about your legs over 25.7 km, fit a 34×34 — the extra sprocket gives you a lifeline on the steepest pitches and keeps your cadence out of the danger zone. On an HC climb, spinning a low gear beats grinding to a standstill.

Summary

Col de Crête Sèche is a proper HC test: long, uneven, and topped by a wall that punishes anyone who arrives tired. Pace it off your threshold, gear low, and treat the 33.44% pitch as the crux to survive on the way to 2088 m.

Length: 25.7 km
Average gradient: 5.96%
Max gradient: 33.44%
Start: 555 m
Summit: 2088 m
Net gain: 1533 m
Total ascent: 1512 m
Category: HC