Collada de Lletó

Overview

Collada de Lletó is a Category 1 climb that packs serious punishment into a compact 9.4 km. From a start elevation of 684 m it rises to a summit of 1536 m, a net gain of 852 m, and it does so at an average gradient of 9.07% — a number that already puts it among the genuinely hard ascents. The category tells you plenty: on a scale where HC is the hardest, then 1, 2, 3 and 4, a Cat-1 rating means this is a climb that decides races and shreds legs. There is nowhere to hide here. Nearly every kilometre asks for real output, and a max gradient of 23.56% guarantees at least one section that turns your ride into a survival exercise.

How the Gradient Unfolds

The shape of Collada de Lletó is defined by its relentlessness. With a 9.07% average sustained across 9.4 km, this is not a climb with a lazy false-flat lead-in that lets you build momentum. Expect the road to bite early and stay steep. The headline hazard is the 23.56% max gradient — a wall that dwarfs the average by more than fourteen points. Sections that steep are short by necessity, but they wreck your rhythm and force you out of the saddle whether you planned to stand or not. Between those spikes the grade rarely relaxes below the demanding range implied by that 9.07% mean. The gap between total ascent (819 m) and net gain (852 m) is small, which tells you the road climbs almost continuously rather than rolling up and down — you gain height with nearly every pedal stroke.

Pacing Notes

The mistake on a climb like this is going out hard and blowing before the top. Anchor your effort to your FTP and hold a sustainable percentage of it, letting the steepest ramps — especially anything approaching that 23.56% pitch — pull you briefly over threshold rather than trying to smooth them out by pushing early. On a 9.07% average you will be near or above threshold more often than you'd like, so bank patience in the opening kilometres. If you don't know your current threshold number, estimate it first with the FTP estimator and set a realistic power ceiling before you start. Ride the first third conservatively, then reassess with the summit's 1536 m in reach.

Gearing

Do not undergear this climb. With a sustained 9.07% and ramps to 23.56%, a compact chainset with a wide-range cassette is the right call. A 34×32 is the sensible minimum for strong climbers, and even they will be grateful for it on the steepest pitches. Most riders should go further and fit a 34×34 to keep cadence alive when the road kicks toward the max gradient. The extra sprocket is cheap insurance against grinding to a walking pace over 9.4 km of climbing.

Summary

Collada de Lletó is a short, savage Category 1 test — steep from the base, punctuated by a leg-breaking wall, and unforgiving all the way to the top. Come with the right gears and a disciplined pacing plan and you'll reach the summit intact.

Length: 9.4 km
Average gradient: 9.07%
Max gradient: 23.56%
Start: 684 m
Summit: 1536 m
Net gain: 852 m
Total ascent: 819 m
Category: 1