Alto de La Cuche

Overview

Alto de La Cuche is a hors catégorie climb, the hardest rating on the books, and its numbers explain why. Over 12.5 km it averages 8.69%, dragging you from a start elevation of 1610 m to a summit at 2697 m. That is a net gain of 1087 m, with a total ascent of 1074 m once the small dips and recoveries are counted. This is not a climb of tricks or false flats — it is a long, high-altitude grind that asks the same hard question again and again for the better part of an hour.

How the Gradient Unfolds

The defining feature here is consistency. An 8.69% average across 12.5 km means there is almost nowhere to hide. The near-match between net gain (1087 m) and total ascent (1074 m) tells you the road climbs almost monotonically — you gain and keep nearly everything, with barely any downhill to give it back. The gradient does swing, though, peaking at 15.78%, so expect ramps that nearly double the average and force you well out of rhythm. Because the summit sits at 2697 m, the thinning air compounds every one of those steep pitches. What would be a manageable 8.69% at sea level bites noticeably harder as you climb toward the top.

Pacing Notes

On a climb this long and this steep, the winning move is discipline early. Settle into an effort you can hold for the full 12.5 km rather than chasing the first steep ramp. A sustainable target sits at or just under your FTP — the power you can hold for roughly an hour, which maps neatly onto this climb's duration. If you don't know yours, run the numbers through the FTP estimator before you go, then treat that figure as a ceiling for the flatter stretches and a reference for spikes toward 15.78%. Over-cook the first few kilometres and the altitude near 2697 m will collect the debt with interest. Keep effort even, breathe deliberately, and let the steep sections cost you cadence rather than blowing your ceiling.

Gearing

With a 8.69% average, ramps to 15.78%, and 1087 m to gain, gear low and never look back. For most riders a compact 34-tooth inner paired with a wide cassette is the right call. A 34×32 is the sensible floor and will get many riders up the steadier stretches, but on a climb that touches 15.78% at altitude, a 34×34 gives you the extra spin to keep cadence alive when the road kicks. If your legs or your day are in question, choose the 34×34 — the lighter gear costs you nothing on the average pitches and buys real insurance on the steep ones.

Summary

Alto de La Cuche is a true HC test: long, steep, and set high enough that the final kilometres feel harder than the gradient alone suggests. Respect the 12.5 km, gear generously, and pace to your ceiling from the bottom.

Length: 12.5 km
Average gradient: 8.69%
Max gradient: 15.78%
Start: 1610 m
Summit: 2697 m
Net gain: 1087 m
Total ascent: 1074 m
Category: HC