Alto de Pasca

Overview

Alto de Pasca is a hors catégorie monster, the kind of climb that reshapes an entire ride around it. Over 42.7 km it lifts you from a start elevation of 1278 m to a summit at 3801 m — a net gain of 2523 m — while the road records a total ascent of 2510 m along the way. The average gradient of 5.91% sounds moderate on paper, but at this length even a "moderate" average adds up to an enormous amount of vertical work. This is an endurance climb first and a steepness climb second, and its HC rating is earned almost entirely by sheer scale.

How the Gradient Unfolds

The headline number is 5.91%, but a 42.7 km climb is never a single steady ramp. That average hides both easier valleys of false-flat and sharp pitches that spike toward the 19.68% maximum. Expect the gradient to breathe: long sustained sections in the mid-single digits punctuated by short, punchy ramps that force you out of rhythm. Because the total ascent (2510 m) sits just below the net gain (2523 m), the profile trends relentlessly upward with almost no descending relief — you climb nearly everything you gain. Thin air compounds the difficulty as you push past 3000 m toward the 3801 m summit, so those steep pitches feel steeper the higher you go.

Pacing Notes

At this length, pacing discipline decides everything. Ride the first two-thirds well within yourself and treat your FTP as a ceiling you rarely touch, not a target you chase. On a climb spanning over 40 km, even small surges compound into deep fatigue long before the summit. Aim to sit comfortably below threshold on the sustained sections and save any hard efforts for the ramps approaching 19.68%, where staying seated and spinning is often more efficient than grinding. If you're unsure of your numbers, run them through the FTP estimator before you go, then set a power or heart-rate cap you promise not to break in the opening hour.

Gearing

Gear for the steep pitches, not the average. With a maximum gradient of 19.68% arriving after you've already climbed thousands of metres, you want a bailout ratio that lets you keep a survivable cadence when your legs are empty. A compact 34-tooth chainring paired with a wide cassette is the sensible baseline: a 34×32 is the minimum many riders will want, and a 34×34 gives welcome extra margin on the harshest ramps and at altitude where every watt costs more. If your setup allows an even easier low gear, take it — nothing is lost by having a bailout you don't use, and plenty is lost by not having one.

Summary

Alto de Pasca is a true hors catégorie test defined by distance and altitude: 42.7 km of climbing that carries you 2523 m upward to a summit at 3801 m. Respect the length, pace conservatively, gear low, and let the average of 5.91% do the damage gradually rather than blowing yourself apart on the 19.68% ramps.

Length: 42.7 km
Average gradient: 5.91%
Max gradient: 19.68%
Start: 1278 m
Summit: 3801 m
Net gain: 2523 m
Total ascent: 2510 m
Category: HC