Puerto de Izaña

Overview

Puerto de Izaña is a genuine hors catégorie (HC) climb, and the numbers tell you why before you turn a pedal. It runs 32.9 km from a start elevation of just 19 m all the way to a 2218 m summit — a net elevation gain of 2199 m, with 2213 m of total ascent when you count every dip and roller. That extra 14 m of climbing hidden inside the total ascent hints at a road that isn't perfectly uniform: there are places where you lose a little height and have to win it back.

At 6.69% average gradient over such an enormous distance, Izaña belongs to the category of climbs that are decided by patience rather than explosiveness. This is not a wall you attack; it is an effort you administer for well over an hour, often much longer.

How the Gradient Unfolds

The headline average of 6.69% is deceptively calm. The max gradient of 15.46% is more than double that, so the climb clearly hides ramps far steeper than the mean suggests. Starting almost at sea level (19 m) and finishing at 2218 m means the air thins noticeably toward the top, and the gradient's steepest pitches — approaching that 15.46% figure — will bite hardest exactly where you have least to give.

Because total ascent (2213 m) sits slightly above net gain (2199 m), expect the profile to undulate rather than climb in a single clean line. Those brief descents break your rhythm and force repeated re-accelerations, each one a small tax over 32.9 km.

Pacing Notes

On a climb this long, power discipline is everything. Anchor your effort to your FTP and resist the urge to chase the steep ramps near the 15.46% pitches — surges early cost you dearly across the remaining kilometres. If you don't know your threshold, run the numbers through the FTP estimator before you commit to a target.

A sensible plan is to ride the shallower sections steadily and simply survive the steepest ramps, letting your average settle near the climb's own 6.69%. With 2199 m of net gain ahead, banking energy early pays off long before the 2218 m summit.

Gearing

With 32.9 km at 6.69% and ramps touching 15.46%, gear low and gear early. A compact 34-tooth inner ring paired with a wide cassette is the smart baseline. A 34×32 will get most fit riders up the shallower gradients while spinning, but the steep pitches near 15.46% are where a 34×34 earns its place — that extra sprocket keeps your cadence alive when the road kicks up. Given the sheer 2199 m of climbing, err toward the easier 34×34 if you're unsure; you will not regret carrying one spare gear over 32.9 km.

Summary

Puerto de Izaña is a full HC test of endurance: 32.9 km of climbing from 19 m to 2218 m, averaging 6.69% with spikes to 15.46%. Pace it by threshold, gear it low, and treat the 2199 m of net gain as a slow burn rather than a sprint.

Length: 32.9 km
Average gradient: 6.69%
Max gradient: 15.46%
Start: 19 m
Summit: 2218 m
Net gain: 2199 m
Total ascent: 2213 m
Category: HC