Alto del Viejo

Overview

Alto del Viejo is a category 1 climb that asks a real question of your legs. Over 12.9 km it gains 817 m of net elevation, lifting you from a start at 1730 m to a summit at 2547 m. The average gradient sits at 6.35%, which reads as steady on paper but hides a sharper reality: the steepest pitches touch 11.15%. With a total ascent of 788 m recorded across its rolling profile, this is a sustained mountain effort at altitude, not a short punch you can muscle over.

The headline numbers — nearly 13 km, a summit well above 2500 m, and a consistent mid-6% slope — put Alto del Viejo firmly in the territory where fitness, patience, and pacing matter more than raw power.

How the Gradient Unfolds

A 6.35% average across 12.9 km means there is nowhere to truly hide, but the climb is not uniform. The gap between the 6.35% average and the 11.15% maximum tells the story: expect the road to swing well above and below its mean. The steeper ramps, closer to 11.15%, are the moments that spike your heart rate and tempt you into the red. Between them, gentler sections offer just enough recovery to reset before the next kick.

Because net gain (817 m) slightly exceeds total ascent (788 m), the profile is almost entirely upward with minimal false-flat relief — you climb, and you keep climbing. Treat the whole ascent as one long block rather than a series of separate hills.

Pacing Notes

The smart way up Alto del Viejo is to anchor your effort to your FTP and refuse to chase the steep ramps. Over 12.9 km at 6.35%, most riders will spend 45 minutes or more on the climb, so an effort you can hold for the full duration is essential. Sitting just below threshold on the shallower sections buys you the headroom to absorb the 11.15% pitches without blowing apart.

If you are unsure of your threshold, run the numbers through the FTP estimator before you plan your target power. Remember that the summit sits at 2547 m, and thinner air at altitude will quietly trim the power you can sustain — pace conservatively early and you will have more to give in the final kilometres.

Gearing

For a 12.9 km climb averaging 6.35% with ramps to 11.15%, gear low and spin. A compact chainring paired with a wide cassette keeps your cadence up and your knees happy on the steep sections. A 34×32 is a sensible baseline for fit climbers, giving you enough range to stay seated on most of the gradient. But if you weigh more, ride at altitude fatigue, or simply want insurance for the 11.15% pitches, step up to a 34×34 — that extra sprocket is the difference between grinding and spinning when the road tilts hardest near 2547 m.

Summary

Alto del Viejo is a genuine mountain test: long enough to reward patience, steep enough to punish overconfidence, and high enough that altitude adds a final sting. Pace it to your threshold, gear down early, and let the numbers guide you to the top.

Length: 12.9 km
Average gradient: 6.35%
Max gradient: 11.15%
Start: 1730 m
Summit: 2547 m
Net gain: 817 m
Total ascent: 788 m
Category: 1