Col de Ciaulonch

Overview

The Col de Ciaulonch is a long, patient category-1 climb that asks for endurance far more than raw explosiveness. Over 25.9 km it lifts you from a valley floor at 721 m to a summit at 2101 m, a net gain of 1380 m. That is a climb you settle into rather than attack — the kind of ascent where the clock, not any single ramp, is the real opponent.

The headline average of 5.32% sounds forgiving, and in isolation it is. But an average is a story about the whole, and 25.9 km is a very long story. Sustained for the better part of an hour or more, that gradient adds up to a serious 1374 m of total ascent, with a peak pitch of 16.1% waiting somewhere along the way to remind you the number on the sign is only the mean.

How the Gradient Unfolds

The gap between the 5.32% average and the 16.1% maximum tells you almost everything about the climb's character. This is not a wall — it is a rolling, uneven ascent where easier stretches are paid back by steeper ones. Because net gain (1380 m) sits just above total ascent (1374 m), the road climbs almost relentlessly upward with very little descending in between; nearly every metre you gain, you keep.

Expect long shallow drags interrupted by short, sharp kicks toward that 16.1% figure. Those spikes are where riders who went out too hard start to unravel. Read the road ahead: on a climb this length, an unnecessary surge over a steep pinch is energy you cannot refund across the remaining kilometres.

Pacing Notes

On a 25.9 km climb, pacing is the whole game. Ride the shallow sections at a steady, sustainable effort — ideally just below your FTP — and let the gradient, not your ego, dictate your power. When the road tilts toward 16.1%, absorb it smoothly rather than spiking hard; a brief over-effort here is fine, but hold your average close to threshold and no higher.

If you do not know your threshold, estimate it first with the FTP estimator so you have a real number to anchor to. Then budget your effort across the full 1380 m of climbing. The riders who finish strongest treat the first two-thirds as a controlled tempo and save any surplus for the final push to 2101 m.

Gearing

For a climb of this length and pitch, err generously on gearing. A compact chainring paired with a wide cassette is the sensible baseline: a 34×32 will carry most fit riders through the sustained sections and let you spin rather than grind. But because the gradient bites to 16.1% and you may hit those ramps with tired legs deep into 25.9 km, a 34×34 gives you a genuine bailout gear. If your bike accepts it, fit the 34×34 — the extra range costs nothing on the flatter stretches and saves your knees on the steep ones.

Summary

The Col de Ciaulonch rewards discipline: pace the 5.32% average, respect the 16.1% ramps, and gear low enough to keep spinning all the way to 2101 m. Get those three things right and the climb becomes a rhythm rather than a fight.

Length: 25.9 km
Average gradient: 5.32%
Max gradient: 16.1%
Start: 721 m
Summit: 2101 m
Net gain: 1380 m
Total ascent: 1374 m
Category: 1