Alto del Buitre

Overview

Alto del Buitre is a hors catégorie climb that measures 33.7 km from base to summit, gaining a net 1976 m as the road lifts from 1549 m to 3525 m. On paper the 5.87% average gradient looks approachable, but two details reset that expectation immediately: the sheer distance, and the fact that the summit sits well above 3500 m, where thin air taxes even well-trained legs. Add a total ascent of 2034 m — more than the net gain, meaning the road dips and recovers along the way — and you have one of the longest sustained efforts you can attempt on a bike.

How the Gradient Unfolds

The 5.87% average is a headline number that hides real variety. Because total ascent (2034 m) exceeds net gain (1976 m), the profile is not a clean, uniform ramp: there are 58 m of descending or false-flat stretches folded into the climb, brief releases that break the rhythm and force you to re-accelerate on a road that is otherwise always pointing up. The defining feature is the 19.39% maximum gradient — a wall more than three times the average. Ramps that steep on a climb this long are punishing precisely because they arrive when you are already deep into a 33.7 km effort. Treat the average as a planning figure, not a promise; the climb is a sequence of steady grades punctuated by sharp pitches and short reprieves.

Pacing Notes

Over 33.7 km, discipline wins. Anchor your effort to a percentage of your FTP rather than to how you feel in the opening kilometres — early enthusiasm is the classic way to blow up before the summit. A sustainable tempo just under threshold is the target for a climb of this duration, backing off further as you approach 3525 m and altitude starts to bite. Reserve headroom for the 19.39% ramps: let your effort spike briefly there, then settle back rather than chasing a steady power number through them. The false-flat sections are your friends — soft-pedal and recover. If you do not know your threshold, estimate it first with the FTP estimator so your pacing targets are grounded in real numbers.

Gearing

Gear for the steep ramps, not the average. On a 5.87% climb most riders spin comfortably, but the 19.39% pitches at over 3000 m of altitude are where an under-geared setup ends the day. A compact 34-tooth chainring paired with a wide cassette is the sensible baseline. A 34×32 will get many fit riders up the walls, but on a climb this long, with fatigue and thin air stacking up, a 34×34 gives you the extra margin to keep a cadence rather than grinding. If your bike accepts it, err toward the easier ratio — spare gears you do not use cost nothing, while gears you wish you had cost the summit.

Summary

Alto del Buitre is a genuine high-altitude test: long, cold, and topping out above 3500 m. Respect the distance, gear low, pace to your threshold, and the 5.87% average becomes a companion rather than an enemy.

Length: 33.7 km
Average gradient: 5.87%
Max gradient: 19.39%
Start: 1549 m
Summit: 3525 m
Net gain: 1976 m
Total ascent: 2034 m
Category: HC