Alto del Parrejón

Overview

Alto del Parrejón is a long, deceptive Category 1 climb that trades brute steepness for sheer duration. Over 23.3 km it lifts you from 1019 m to a summit of 1988 m — a net gain of 969 m. The rolling profile means the road actually gives back a little height along the way, so the total ascent comes in slightly higher at 978 m. On paper the 4.15% average reads as gentle, almost a false flat. In reality that number is an average, and averages lie: a lone ramp hits 24.02%, a wall steep enough to stop an unprepared rider dead. This is a climb that rewards patience and punishes anyone who mistakes the mild headline gradient for an easy day.

How the Gradient Unfolds

Think of Parrejón as a long, gently tilted ribbon with one vicious kink in it. For most of the 23.3 km the grade sits close to the 4.15% average — the kind of slope you can hold in the saddle, breathing hard but never buried. Because the summit is 1988 m and the start is 1019 m, you gain 969 m of altitude, but the extra 9 m of total ascent over net gain tells you the road dips and recovers rather than climbing in a clean line. Those small descents are gifts and traps: they let you recover, but they also break rhythm and steal momentum before the next drag. The defining feature is that 24.02% maximum. It is nearly six times the average, so it will not sit quietly in the profile — it arrives as a genuine wall, likely short but brutal, demanding a hard gear change and a decisive effort.

Pacing Notes

On a climb this long, discipline beats bravado. Anchor your effort to your FTP and hold a steady, sustainable output across the shallow majority rather than surging. If you are not sure what wattage that means for you, run the numbers through the FTP estimator before you ride. The trap here is the modest 4.15% average tempting you to push too big a gear early; 23.3 km is plenty of time to blow up. Ride the flatter kilometres at or just below threshold, then leave a genuine reserve for the 24.02% ramp — a pitch that steep can spike you well over FTP for its duration no matter how conservatively you pace. Recover on the dips, stay seated where you can, and treat the wall as the one moment you are allowed to spend deep.

Gearing

Gear for the wall, not the average. The 4.15% mean is comfortable on almost any setup, but the 24.02% maximum is what dictates your cassette. On a compact 34-tooth chainring, a 34×32 will get most fit riders over the steep pitch, but at 24% you will be grinding hard and slow. If you have the option, a 34×34 buys precious extra torque and lets you keep a survivable cadence when the road rears up. Given the 23.3 km length, protecting your legs early matters as much as clearing the ramp, so err toward the easier 34×34 rather than muscling a bigger gear across 969 m of climbing.

Summary

Alto del Parrejón is a long-haul Category 1 climb defined by contrast: a mild 4.15% average masking a 24.02% wall, spread across 23.3 km and 969 m of net elevation gain to a high summit. Pace it patiently, gear for the steep, and respect the distance.

Length: 23.3 km
Average gradient: 4.15%
Max gradient: 24.02%
Start: 1019 m
Summit: 1988 m
Net gain: 969 m
Total ascent: 978 m
Category: 1