Alto del Mico

Overview

Alto del Mico is an hors-catégorie monster, the kind of ascent that rewrites your definition of a hard day. From the base at 992 m the road climbs 20.8 km to a summit sitting at 2542 m, a net gain of 1550 m across an average gradient of 7.45%. That combination — genuinely long, genuinely steep, and finishing well over 2500 m — is what earns it the HC label, the top rung above categories 1 through 4. There is no easy way up. The total ascent of 1549 m almost exactly matches the net gain, which tells you the climb barely relents once it starts: no descents to recover, no false valleys to coast through, just a continuous drag toward the sky.

How the Gradient Unfolds

A 7.45% average over 20.8 km is punishing on its own, but averages hide the teeth. With a maximum gradient of 28.4%, this climb has ramps that are nearly four times steeper than its mean. That gap between 7.45% and 28.4% is the story here: long stretches near the average are stitched together with savage pitches that force you out of any comfortable rhythm. Because net gain (1550 m) and total ascent (1549 m) sit within a metre of each other, you can assume the road climbs almost the entire way — every kilometre you tick off is a kilometre spent gaining altitude. Expect the steepest walls to arrive without warning, spiking the effort long before the 2542 m summit.

Pacing Notes

On a climb this long, discipline beats bravado. Your target power should sit around threshold, so know your FTP before you start and hold something in reserve for the max-gradient ramps, where the road briefly demands far more than 7.45%. Over 20.8 km, going even slightly too hard early will cost you dearly near the top, where thin air at 2542 m compounds the fatigue. If you are not certain of your numbers, run them through the FTP estimator first and set a ceiling you refuse to cross on the shallower sections. Let the pitches spike your effort briefly, then settle straight back to your steady number.

Gearing

Gear for the max, not the average. A 28.4% wall on tired legs will overwhelm anything built for rolling terrain, so bring a wide-range cassette. A compact 34-tooth chainring paired with a 34×32 low gear is the sensible baseline for the sustained 7.45% stretches, but on the steepest ramps most riders will be grateful for a 34×34. Given the 1550 m of climbing and the length, err toward the easier setup — spinning a low gear preserves your legs for the full 20.8 km far better than grinding a ratio that is a touch too tall.

Summary

Alto del Mico is a true HC test: long, steep, and high. Respect the 28.4% pitches, gear low, and pace to your threshold, and the 2542 m summit is within reach.

Length: 20.8 km
Average gradient: 7.45%
Max gradient: 28.4%
Start: 992 m
Summit: 2542 m
Net gain: 1550 m
Total ascent: 1549 m
Category: HC