Alto de Rabona

Overview

Alto de Rabona is a genuine hors catégorie monster, the kind of climb that measures your day rather than merely inconveniencing it. It runs 42.5 km from base to summit, lifting you from a start elevation of 1984 m to a thin-aired 4072 m at the top. The headline average is a deceptively modest 4.91%, but that number hides a wild internal story: the maximum pitch bites at 27.23%, roughly five and a half times the average. Over the full ascent you gain 2088 m net, while your legs actually do 2441 m of total climbing — the extra 353 m coming from the dips and false flats that punctuate the route. This is an HC climb for good reason.

How the Gradient Unfolds

Do not trust the 4.91% average to describe any single kilometre of Rabona. With a maximum of 27.23% recorded on the climb, the profile is anything but uniform. That gap between the 2088 m net gain and the 2441 m of total ascent tells you the road is not a clean, one-way ramp — it rolls, sags, and rears back up, meaning some of your hardest efforts come after brief descents that offer no real rest. Expect long stretches sitting near the average punctuated by sharp ramps far steeper than 4.91%. The steepest sections are where a 42.5 km climb turns from an endurance test into a survival exercise, especially with the summit sitting at 4072 m where the air is measurably thinner.

Pacing Notes

Over 42.5 km, discipline beats bravado. Anchor your effort to your FTP and hold well below it on the long averaged sections so you have headroom for the ramps toward 27.23%. If you are unsure of your number, run the FTP estimator before you commit to a target. Remember that the summit at 4072 m means altitude will quietly shave power off your legs, so the wattage that feels easy at the 1984 m base will feel harder near the top. Pace the first two-thirds like an accountant; spend only on the steepest pitches where staying seated is not an option.

Gearing

An HC climb this long with pitches at 27.23% demands compact, forgiving gearing. A 34×32 is the sensible floor for strong riders, but on a climb that gains 2441 m of total ascent and touches 27.23%, most cyclists will be far happier with a 34×34. That extra sprocket buys you the cadence to spin the vicious ramps instead of grinding them, preserving your legs for the sheer 42.5 km length and the altitude at 4072 m. Fit the widest cassette your derailleur allows.

Summary

Alto de Rabona rewards patience, humility, and gearing chosen for survival rather than pride. Respect the 42.5 km distance, ration your effort against the 27.23% spikes, and let the thin air at 4072 m dictate a conservative pace.

Length: 42.5 km
Average gradient: 4.91%
Max gradient: 27.23%
Start: 1984 m
Summit: 4072 m
Net gain: 2088 m
Total ascent: 2441 m
Category: HC