Col de Bretolet (VS)

Overview

Col de Bretolet (VS) is a long, patient category-1 effort that rewards discipline over aggression. Over 23.7 km the road lifts you from 411 m at the base to 1718 m at the summit, a net elevation gain of 1307 m. The average gradient reads a moderate 5.52%, but that figure hides the character of the climb: with a total ascent of 1430 m against 1307 m of net gain, the profile clearly rolls and dips rather than climbing in one smooth line. Add the 26.8% maximum pitch and you have a climb that is far spikier than its average suggests.

How the Gradient Unfolds

The 5.52% average is a useful planning number, but it is not the number that will hurt you. The gap between the 1430 m of total ascent and the 1307 m of net gain means roughly 123 m of the day is spent regaining height you had already earned — false flats, brief descents, and undulations that break momentum across 23.7 km. Somewhere in that distance sits the 26.8% maximum ramp, a gradient nearly five times the average. On a climb this long, a single pitch that steep can spike your effort well past a sustainable level if you hit it carrying too much speed or too big a gear. Treat the averages as the backdrop and the steep sections as the moments that decide your day.

Pacing Notes

On a 23.7 km climb, pacing is everything. Anchor your effort to your FTP and hold a steady, repeatable power rather than chasing the terrain. A climb of this length is best ridden just under threshold on the sustained sections, leaving headroom to absorb the 26.8% ramp without blowing apart. If you do not know your threshold, run the numbers first with the FTP estimator so your target wattage matches the 1307 m you have to gain. The undulating profile tempts you to surge on the flatter parts — resist it, because every match burned early is one you will miss when the gradient bites.

Gearing

With a maximum gradient of 26.8% and 1430 m of total ascent, gear low and gear early. A compact 34-tooth chainring paired with at least a 32-tooth cassette sprocket — a 34×32 — is the sensible baseline for most riders on a climb of this length. If your legs favour a spinning cadence, or you expect fatigue to stack up across 23.7 km, size up to a 34×34 for extra insurance on the steepest pitch. The extra range costs you nothing on the gentler 5.52% stretches and buys you a survivable cadence when the road stands up.

Summary

Col de Bretolet (VS) is a long category-1 climb defined by its length and its spikes rather than its modest average. Pace it to your threshold, gear low for the steep ramp, and let the 23.7 km come to you.

Length: 23.7 km
Average gradient: 5.52%
Max gradient: 26.8%
Start: 411 m
Summit: 1718 m
Net gain: 1307 m
Total ascent: 1430 m
Category: 1