Puerto de Erjos

Overview

Puerto de Erjos is an HC climb — hors catégorie, the hardest rung on the scale before the numbered categories 1 through 4. Over 14.6 km it lifts you from just 6 m near sea level all the way to a 1102 m summit, a net gain of 1096 m. The average gradient is a stiff 7.5%, and with a max pitch of 30.4% this is a climb that punishes any rider who arrives with the wrong plan. Starting almost at the waterline and finishing above 1100 m, it delivers the kind of uninterrupted vertical that defines the category.

How the Gradient Unfolds

The headline number is 7.5% averaged across 14.6 km, but averages hide the story. With a maximum of 30.4%, the road clearly contains ramps far steeper than the mean — spikes more than four times the average gradient. That gap between the 7.5% average and the 30.4% peak is the single most important thing to understand here. Total ascent is logged at 1086 m against a net gain of 1096 m, meaning the road climbs relentlessly with essentially no meaningful descending to recover on. Expect long, sustained pitches broken by short, savage kicks that force you well out of any comfortable rhythm.

Pacing Notes

On a climb this long, discipline beats ambition. Anchor your effort to your FTP and hold something in reserve for the ramps toward 30.4%. If you spend recklessly on the early slopes, the back half of 14.6 km will unravel you. A good approach is to ride the sustained 7.5% sections just under threshold, then absorb the steep spikes as brief over-threshold surges rather than trying to hold power steady through them. If you are unsure of your number, run the FTP estimator before you commit to a target, then translate that figure into a climbing power ceiling you can actually sustain for the roughly 14.6 km of effort ahead.

Gearing

Gear for the 30.4% max, not the 7.5% average — that is the mistake most riders make. A compact 34-tooth inner chainring is the sensible starting point. Paired with a 34×32, you have a low ratio that covers most of the sustained gradient, but the steepest pitches on this climb will still have you grinding. For most amateurs tackling an HC climb of this length with ramps this severe, a 34×34 is the smarter choice, giving you an extra sprocket of relief so you can spin rather than lurch through the worst of it. If your derailleur and cassette allow anything lower, take it — over 14.6 km and 1096 m of gain, a spare gear is never wasted.

Summary

Puerto de Erjos is a genuine HC effort: 14.6 km of near-constant climbing from 6 m to 1102 m, averaging 7.5% but hiding pitches up to 30.4%. Pace it to your threshold, gear low, and respect the length. Do that, and the 1096 m of net gain becomes a summit to savour rather than survive.

Length: 14.6 km
Average gradient: 7.5%
Max gradient: 30.4%
Start: 6 m
Summit: 1102 m
Net gain: 1096 m
Total ascent: 1086 m
Category: HC