Alto de Los Muertos

Overview

Alto de Los Muertos is an hors catégorie climb, the hardest rating in cycling, and the numbers explain why. Over 13 km it averages a brutal 11.76% gradient, dragging you from a start elevation of 1054 m up to a 2588 m summit. That is 1534 m of net elevation gain, with 1486 m of total ascent packed into a road that barely gives anything back. There is no long valley approach and no rolling false-flat to warm into — an 11.76% average across a full 13 km means the climbing starts almost immediately and refuses to stop.

For context, plenty of famous HC climbs sit closer to 8%. Los Muertos runs well beyond that for its entire length, and it tops out with a max gradient of 31.44% — a wall steep enough that momentum and gearing, not just fitness, decide whether you keep turning the pedals.

How the Gradient Unfolds

The shape here is defined by its relentlessness. With a net gain of 1534 m over 13 km and only 1486 m of total ascent, the difference between the two figures is small — just 48 m of descending or flattening across the whole climb. In plain terms, almost every metre you gain, you keep. There are no meaningful recovery sections to reset your legs.

The 11.76% average tells you what to expect on the "easy" stretches, and the 31.44% max marks the pitches that will spike your effort deep into the red. When a climb averages this high, the steep ramps are not brief anomalies — they are the character of the road. Expect to grind, not glide.

Pacing Notes

On a climb this steep and this long, pacing is survival. Your FTP is the single most useful number to know before you start, because at an 11.76% average you cannot coast through mistakes — go too hard early and the upper slopes toward 2588 m will end your day.

Aim to hold a steady, sustainable effort just under threshold on the average pitches, and accept short surges above it on the ramps toward 31.44% where staying upright demands power. If you do not know your threshold, run the numbers first with the FTP estimator and set a ceiling you can defend for the full 13 km. Thin air near the 2588 m summit compounds every watt, so bank effort early rather than spending it.

Gearing

Gear for the wall, not the average. At 11.76% sustained with pitches to 31.44%, most riders will want the lowest ratio they can fit. A compact 34-tooth chainring paired with a wide cassette is the baseline: 34×32 is the minimum many strong climbers should consider, and 34×34 gives you crucial extra room for the steepest ramps and the altitude near the top.

If your setup allows an even easier ratio, take it — spinning a low gear beats grinding to a standstill on a 31.44% pitch. There is no shame in the smallest cog you own here.

Summary

Alto de Los Muertos is an uncompromising HC climb: steep from the base, steeper at the top, and long enough that fitness, pacing and gearing all have to line up. Respect the 31.44% wall, gear low, and hold a disciplined effort to the summit.

Length: 13 km
Average gradient: 11.76%
Max gradient: 31.44%
Start: 1054 m
Summit: 2588 m
Net gain: 1534 m
Total ascent: 1486 m
Category: HC