Alto de la Siberia

Overview

Alto de la Siberia is a genuine hors catégorie (HC) climb, the hardest classification on the road. Over 20.7 km it drags you from a valley floor at 588 m up to a summit of 2353 m, a net elevation gain of 1765 m. The average gradient is a relentless 8.52%, and at its worst the road kicks up to a savage 33.39%. Total ascent along the way tallies 1753 m, meaning almost every metre of the climb points skyward with barely a false flat to break the rhythm. This is not a climb you survive on fitness alone; it demands respect, patience, and honest gearing.

How the Gradient Unfolds

The defining number here is the 8.52% average sustained across the full 20.7 km. That is a punishing figure to hold for such distance, and it means there is no long shallow runway to warm into. With a net gain of 1765 m over 20.7 km, the mountain rarely relents. The 33.39% max gradient is the sting in the tail: a wall far steeper than the average that will spike your effort well beyond threshold in an instant. Expect the climb to alternate between grinding sustained ramps in the 8–10% range and short, brutal pitches where the road rears up. Because total ascent (1753 m) sits so close to net gain (1765 m), you can trust that once you go up, you stay up.

Pacing Notes

On a climb this long, pacing is everything. Ride the first several kilometres well within yourself, treating your FTP as a ceiling rather than a target for the sustained sections. At 8.52% average over 20.7 km, you will be climbing for a long time, so aim to sit comfortably below threshold and save headroom for the steep pitches, where holding any cadence at all near 33.39% will drive your power far above where you want it. If you are unsure of your numbers, run them through the FTP estimator before you commit to a pace. The riders who blow up here are the ones who chase the early ramps; the riders who summit strong are the ones who treat the whole 1765 m of climbing as a single, measured effort.

Gearing

Gear for the worst pitch, not the average. With a 33.39% maximum and 20.7 km of sustained 8.52% work, this is a climb where compact gearing is the bare minimum. A 34×32 will get most fit riders up the sustained sections, but the steepest ramps will have you standing and straining. For the majority, a 34×34 is the smarter choice — that extra sprocket buys you a survivable cadence when the road hits its steepest, and over 1765 m of vertical it protects your legs for the summit. If your bike can take it, go easier still; nobody regrets a bailout gear on an HC climb.

Summary

Alto de la Siberia is a full HC test: long, steep, and unforgiving, with a wall near the top that punishes anyone who arrives already spent. Pace it honestly, gear it generously, and the 2353 m summit is yours.

Length: 20.7 km
Average gradient: 8.52%
Max gradient: 33.39%
Start: 588 m
Summit: 2353 m
Net gain: 1765 m
Total ascent: 1753 m
Category: HC