Col de Bise

Overview

Col de Bise is one of those climbs that reads like a typo until you're on it. Over 11.5 km it averages 13.16%, a figure so steep it barely feels real when you say it out loud. Starting at 389 m and topping out at 1907 m, the road hauls you up 1518 m of net elevation, with 1463 m of total ascent packed into a relentless, unforgiving line. It carries the HC (hors catégorie) label — the hardest rating there is, beyond categories 1 through 4 — and it earns every letter of it.

How the Gradient Unfolds

The number that defines Col de Bise is its average: 13.16% sustained across the full 11.5 km. There is no long valley run-in inflating an easy start, and no flat plateau to hide the pain. A 13.16% average over that distance means very little of the climb offers relief — where most HC climbs give you 8 or 9%, this one simply does not let up.

The real teeth are in the max gradient of 27.36%. That is more than double the average, and ramps of that severity change how you ride entirely. On pitches approaching 27.36% you are no longer pacing so much as surviving each pedal stroke. Because the net gain (1518 m) exceeds the total ascent figure (1463 m), the profile is a near-continuous upward grind rather than a saw-tooth of ups and downs — you climb, and then you keep climbing.

Pacing Notes

On a climb this steep, discipline beats bravado every time. Your FTP is the anchor for the whole effort: at 13.16% average, small surges above threshold compound fast and can end your day well before the summit. If you don't have a current threshold figure, run the numbers through the FTP estimator before you plan your ride.

The tactic is to bank nothing early. Ride the opening kilometers slightly below what feels comfortable, because the 27.36% ramps will demand everything in reserve. Hold a steady percentage of threshold, let your cadence drop where it must, and treat the full 11.5 km as one long effort rather than a series of attacks. The summit at 1907 m rewards patience, not heroics.

Gearing

Do not under-gear this one. With a 13.16% average and pitches at 27.36%, most riders should treat a compact 34-tooth chainring as the starting point, not the fallback. Pair it with the widest cassette you can fit. A 34×32 is the bare minimum here, and honestly it will feel marginal on the steepest ramps. A 34×34 gives you the extra breathing room that keeps your cadence turning and your knees intact across all 11.5 km. If your bike accepts something even larger, use it — on Col de Bise there is no such thing as a gear that's too easy.

Summary

Col de Bise is a pure test of climbing: short in distance, savage in gradient, and merciless from bottom to top. Gear low, pace conservatively, and respect the 27.36% ramps. Do that, and the 1907 m summit is yours.

Length: 11.5 km
Average gradient: 13.16%
Max gradient: 27.36%
Start: 389 m
Summit: 1907 m
Net gain: 1518 m
Total ascent: 1463 m
Category: HC