Alto del Zar

Overview

Alto del Zar is a hors catégorie monster measured in scale rather than steepness. Across 33.5 km it climbs from 1136 m at the base to a lofty summit of 3034 m, a net gain of 1898 m and a total ascent of 1901 m once the small dips along the way are counted. The average gradient of 5.67% sounds humane on paper, but at this length the numbers add up mercilessly — you are climbing for well over an hour of pure elevation, and the final kilometres unfold above 3000 m where thin air taxes even seasoned climbers. This is a climb that rewards patience, discipline, and honest self-knowledge far more than raw power.

How the Gradient Unfolds

The 5.67% average hides real variety. With a maximum pitch of 19.4%, Alto del Zar clearly stacks gentle drags against savage ramps rather than holding a constant tilt. Expect long stretches near or below the average that let you settle into a rhythm, punctuated by sharp kicks that briefly quadruple the effort. The 3 m gap between the 1898 m net gain and the 1901 m total ascent tells you there are false flats and short descents woven in — small reliefs that break the climb into digestible blocks but also disrupt any steady cadence. Read the road ahead: keep something in reserve for the moments the gradient stabs toward 19.4%.

Pacing Notes

On a climb this long, pacing is everything. Anchor your effort to your FTP and aim to sit comfortably below it for the bulk of the 33.5 km, saving the burning matches for the steepest ramps. If you do not know your threshold, run the numbers through the FTP estimator before you commit — going out too hard here is a mistake you cannot claw back over the remaining distance. Factor in the altitude too: the top of the climb sits at 3034 m, and power that felt sustainable at 1136 m will feel harder as the air thins. Ride within yourself early and you will still be pedalling strongly when the summit finally appears.

Gearing

Length and altitude both argue for generous gearing. A compact 34-tooth front paired with a wide cassette is the sensible baseline: 34×32 will get most fit riders up the average slopes, but the 19.4% ramps — attacked with tired legs after hours of climbing — make a case for the extra relief of 34×34. If your bike and derailleur allow it, err toward the easier ratio; spinning a low gear preserves your muscles for the thin-air finale far better than grinding. On a climb of 33.5 km, there is no prize for over-geared heroics.

Summary

Alto del Zar is a genuine HC test — not for a single wall, but for the sheer accumulation of 1898 m of climbing across 33.5 km, finishing in the rarefied air above 3000 m. Pace it honestly, gear it generously, and respect the distance.

Length: 33.5 km
Average gradient: 5.67%
Max gradient: 19.4%
Start: 1136 m
Summit: 3034 m
Net gain: 1898 m
Total ascent: 1901 m
Category: HC