Collado de Lois

Overview

Collado de Lois is not a climb you ride into casually. Over just 6.2 km it averages a savage 13.79%, and the road bites all the way to a maximum of 34.38%. That is an average steeper than most riders ever see, sustained for the length of a serious effort. It is rated HC — hors catégorie, the hardest tier above categories 1 through 4 — and it earns that rating on gradient alone. From a start elevation of 688 m to a summit at 1544 m, you gain 856 m net over those 6.2 km. The total ascent registers at 836 m, meaning the road climbs almost relentlessly with barely a false flat to recover on.

How the Gradient Unfolds

The defining feature of Collado de Lois is that there is nowhere to hide. A 13.79% average across 6.2 km means the "easy" sections are still steep, and the hard sections are extraordinary. When a climb peaks at 34.38%, those ramps arrive as genuine walls — pitches where staying seated becomes impossible and momentum evaporates in a single pedal stroke. With 856 m of net gain and 836 m of total ascent, the near-total absence of descent tells the story: this is a continuous vertical grind rather than a rolling profile. Expect the gradient to swing well above and below its 13.79% mean, so read the road ahead and brace for the steepest kicks.

Pacing Notes

On a climb this steep, pacing is really power management. Your FTP sets the ceiling, but on ramps touching 34.38% you will spike far above it whether you like it or not — the goal is to limit how often and how long. Ride the shallower stretches conservatively so you hold a reserve for the walls, because a 13.79% average leaves no flat to recover. If you do not know your threshold, run the numbers through the FTP estimator before you attempt this, then plan an effort that keeps you out of the red on the lower slopes and lets you survive the pitches near the top of the 856 m gain.

Gearing

Gear as low as you reasonably can. On a 6.2 km climb averaging 13.79% with 34.38% ramps, standard compact gearing will not be enough for most riders. A 34×32 is the bare minimum here, and even strong climbers will be grinding through the steepest sections at very low cadence. A 34×34 is the smarter choice — that extra sprocket buys you cadence and spares your knees when the road rears up toward its maximum. If your setup allows an even easier ratio, use it; on Collado de Lois there is no such thing as too low a gear.

Summary

Collado de Lois compresses a full HC challenge into 6.2 km. It is short only on paper — a 13.79% average and a 34.38% max make it one of the most punishing walls you can point a bike at. Come with the lowest gearing you own, a clear pacing plan, and respect for every one of the 856 m it makes you climb.

Length: 6.2 km
Average gradient: 13.79%
Max gradient: 34.38%
Start: 688 m
Summit: 1544 m
Net gain: 856 m
Total ascent: 836 m
Category: HC