Alto del Buey

Overview

Alto del Buey is not a climb you talk yourself into on a whim. Over 10.7 km it averages a staggering 14.98% gradient, and that single number tells you almost everything you need to know: this is one of the steepest sustained ascents you will ever attempt on a bike. It carries the HC (hors catégorie) rating — the top of the scale, above categories 1 through 4 — and it earns it without any theatrics. There is no gentle preamble, no rolling false flat to hide behind. You start at 1585 m of elevation and finish at 3190 m, a net gain of 1605 m, with 1530 m of total ascent packed into those 10.7 kilometres.

How the Gradient Unfolds

The defining feature of Alto del Buey is relentlessness. A 14.98% average over 10.7 km means there is essentially nowhere to recover. On most long climbs the average is a blend of steep pitches and easier ramps; here the average is the road. Because net gain (1605 m) sits close to total ascent (1530 m), you can infer the climb almost never gives elevation back — it points up and stays up, with only the smallest of respites. Thin air compounds the difficulty: finishing at 3190 m means the final kilometres are ridden with meaningfully less oxygen than at the 1585 m start, so the same gradient that hurt early will hurt more late.

Pacing Notes

At this gradient, pacing is survival. The temptation is to attack the lower slopes while your legs are fresh, but 10.7 km of near-15% terrain will punish any early enthusiasm brutally. Anchor your effort to your FTP and hold a power ceiling you know you can sustain for the full duration, then subtract a little for the altitude you will hit near the 3190 m summit. If you do not have a reliable FTP figure, run the numbers through the FTP estimator before you commit to this one — going in blind on a climb this steep is how rides fall apart. Ride the whole thing as a single, even, disciplined effort. There is no reward for surges here, only for consistency across all 1605 m of vertical.

Gearing

Do not under-gear this climb. A 14.98% average sustained for 10.7 km will overwhelm the compact setups that handle most HC climbs comfortably. A 34×32 is the bare minimum I would suggest, and even strong climbers will be grinding at low cadence for long stretches with it. For most riders, a 34×34 is the smarter choice — that extra sprocket buys you cadence, protects your knees over a full hour-plus of climbing, and keeps you spinning rather than heaving. If your bike accepts it, err toward the easier ratio. On Alto del Buey, a gear too easy costs you nothing; a gear too hard can end your day.

Summary

Alto del Buey is a pure test of climbing: steep, long, high, and utterly unforgiving. Respect the 14.98% average, gear low, pace with discipline, and let the summit at 3190 m come to you.

Length: 10.7 km
Average gradient: 14.98%
Max gradient: n/a
Start: 1585 m
Summit: 3190 m
Net gain: 1605 m
Total ascent: 1530 m
Category: HC