Alto de Los Giles

Overview

Alto de Los Giles is a short, uncompromising category 2 climb that trades length for relentless steepness. Over just 4.4 km it averages 8.71%, a figure that puts it firmly in the "no rest" bracket. You start at 1504 m and top out at 1883 m, so the road carries you 379 m higher over the course of the ascent. That combination — brief, brutal, and set at altitude — makes it a climb where the effort is concentrated rather than drawn out, and where a bad opening few minutes can cost you the whole thing.

How the Gradient Unfolds

The defining feature here is the gap between the average and the maximum. At 8.71% the mean gradient is already demanding, but the road ramps as steep as 12.49% at its worst pitch. That spread of nearly four points tells you the surface is not evenly loaded: there are stretches that sit close to the average and steeper ramps that spike well above it. With the net gain at 379 m and the total ascent measured at 359 m, the road climbs almost continuously — there is very little false-flat or downhill relief to reset your legs. Expect a wall-like feel where the steepest sections arrive as sharp punches rather than gradual builds, and where the average never lets up enough to let you truly recover in the saddle.

Pacing Notes

On a climb this short and steep, pacing is about restraint at the bottom. The temptation is to attack the opening ramps, but at 8.71% average for 4.4 km, going into the red early leaves nothing for the 12.49% pitches later. Ride it just under your threshold — your FTP is the number that matters most here, because a climb of this duration is essentially a sustained threshold effort with surges layered on top. If you do not know yours, run the numbers through the FTP estimator before you plan your target power. Aim to hold steady on the average sections and accept a brief effort above threshold on the steepest ramps, then settle back as soon as the gradient eases.

Gearing

Do not underestimate what 8.71% average with 12.49% spikes demands of your legs at altitude. For most riders a compact 34-tooth chainring paired with a wide cassette is the right call. A 34×32 will get many riders up cleanly if their threshold is strong and their cadence holds. But given the max pitch and the sustained steepness, a 34×34 is the safer, smarter choice — that extra sprocket protects your knees on the ramps and keeps your cadence in a workable range when the road bites hardest. If in doubt, gear low: spinning beats grinding on a wall like this.

Summary

Alto de Los Giles is a compact category 2 test that rewards patience early and grit late. Respect the opening, save something for the 12.49% ramps, and gear low enough to keep spinning.

Length: 4.4 km
Average gradient: 8.71%
Max gradient: 12.49%
Start: 1504 m
Summit: 1883 m
Net gain: 379 m
Total ascent: 359 m
Category: 2