Collado de Llesba

Overview

Collado de Llesba is a genuine hors catégorie (HC) climb — the hardest rung on the categorisation ladder, above categories 1, 2, 3 and 4. Over 19.5 km it drags you from a valley floor at 377 m up to a summit at 1666 m, a net elevation gain of 1289 m. The average gradient of 6.62% sounds civil enough on paper, but averages hide the story on a climb this long. With ramps reaching 18.99%, Llesba is a climb that punishes anyone who treats the mean as the enemy. It is a full-hour effort or longer for most riders, and it rewards patience far more than aggression.

How the Gradient Unfolds

The gap between the 1289 m net gain and the 1273 m of total ascent is small, which tells you this is a relentlessly upward climb — there is very little false-flat or descending to recover on. You are climbing almost the entire 19.5 km. That said, a 6.62% average that spikes to 18.99% cannot be uniform. Expect the profile to breathe: stretches close to the average punctuated by sharp, muscular kicks well into the teens. The steepest pitches are where a mistimed effort will cost you, because there is no flat section afterwards to absorb the damage — the road simply keeps rising toward 1666 m.

Pacing Notes

Long HC climbs are won and lost on discipline. Anchor your effort to your sustainable power rather than to how the road feels in the first few kilometres. Riding just under your FTP for the shallower sections buys you the headroom to survive the 18.99% ramps without redlining. If you do not know your current threshold, estimate it first with the FTP estimator and pace from a real number, not a guess. On a 1289 m ascent the temptation to chase early is strong; resist it. Bank nothing in the first third that you cannot repay across the remaining distance to the top.

Gearing

With 19.5 km at 6.62% average and pitches to 18.99%, gear generously. A compact 34-tooth chainring paired with a 34×32 low is a sensible starting point for strong climbers, giving you a spin-able ratio on the sustained sections. But given how steep Llesba gets, most riders will be glad of a 34×34 for the double-digit ramps — that extra sprocket is the difference between grinding and stalling when the road tilts toward 18.99%. On a climb this long, a lower gear you rarely use costs nothing and saves everything.

Summary

Collado de Llesba is a complete HC climb: long, steep, and unrelenting from 377 m to 1666 m. Pace it to your threshold, gear for the worst ramps, and let the 19.5 km come to you.

Length: 19.5 km
Average gradient: 6.62%
Max gradient: 18.99%
Start: 377 m
Summit: 1666 m
Net gain: 1289 m
Total ascent: 1273 m
Category: HC