Alto del Perro

Overview

Alto del Perro is a long, honest Category 1 haul. Over 26.7 km it lifts you from 710 m to a summit of 2109 m, a net gain of 1399 m at an average gradient of 5.23%. That average is deceptively calm: the total ascent of 1512 m tells you the road never simply pins one grade and holds it. Instead it rolls, dips, and reloads, so the climbing you do adds up to more than the raw elevation difference. With a maximum pitch of 11.75%, there are moments where the friendly average evaporates entirely and you are left grinding a wall.

At this length, Alto del Perro is less a sprint effort and more an exercise in patience. You will be on the slope for the better part of an hour or more, so how you meter the first two-thirds decides how the summit feels.

How the Gradient Unfolds

The number to respect is the gap between average and maximum. A 5.23% mean paired with an 11.75% peak means the climb is not evenly graded — it hides steep punches inside long, moderate stretches. Because total ascent (1512 m) exceeds net gain (1399 m), the profile includes short descents or flatter reprieves that briefly hand back altitude, only to demand it again. Treat every easing as recovery, not as a signal the hard work is done. The steepest ramps toward 11.75% are where riders who went out too hard start to unravel; the shallower kilometres are where a disciplined rider quietly banks time.

Pacing Notes

On a climb this long, pace off your sustainable power, not your ego. A good target is riding just below your FTP so you have headroom left when the gradient spikes toward 11.75%. If you do not know your threshold, run the numbers through the FTP estimator before you commit to the climb.

Break the 26.7 km into thirds. Ride the first third comfortably under threshold, settle into a rhythm through the middle, and only spend matches on the steepest pitches near the top once you know the summit at 2109 m is within reach. The 1399 m of net gain is earned slowly — respect it early and the last kilometres reward you.

Gearing

For a 26.7 km climb averaging 5.23% with ramps to 11.75%, gearing generosity beats bravado. A compact 34-tooth inner chainring paired with a wide cassette is the sensible choice. A 34×32 gives most fit riders enough range to stay seated and spin through the moderate stretches. But given the 11.75% maximum and the sheer duration, dropping to a 34×34 is worth it — the extra sprocket keeps your cadence up when fatigue accumulates over 1399 m of climbing and the pitches steepen. Err toward the easier gear; you will never regret a spare cog on a climb this long.

Summary

Alto del Perro rewards patience: a long Category 1 effort where the modest 5.23% average masks steep ramps and a genuine 1399 m of altitude to conquer. Pace it low, gear it easy, and let the summit come to you.

Length: 26.7 km
Average gradient: 5.23%
Max gradient: 11.75%
Start: 710 m
Summit: 2109 m
Net gain: 1399 m
Total ascent: 1512 m
Category: 1