Alto de San Pablo

Overview

Alto de San Pablo is a genuine long-haul ascent: 21.8 km of climbing at a 6.03% average gradient, lifting you from a 775 m start to a 2089 m summit. That is 1314 m of net elevation gain, with 1425 m of total ascent once the minor dips along the way are counted. As a category-1 climb it sits just one rung below hors catégorie, and the length alone puts it in serious company — this is an effort measured in tens of minutes, not seconds. The steepest ramp bites at 13.7%, so while the average reads as steady, the climb has real teeth.

How the Gradient Unfolds

A 6.03% average over 21.8 km sounds uniform, but the gap between that mean and the 13.7% maximum tells the real story. The extra 111 m between the 1314 m net gain and the 1425 m total ascent means the road is not a single clean drag — there are short reliefs and false flats where the grade eases, followed by pitches that swing well above average to make up the difference. Expect to settle into a rhythm around the 6% baseline, then repeatedly stand or shift as the gradient jumps toward double digits. The final approach to 2089 m also means thinning air, so the same power costs you more the higher you climb.

Pacing Notes

On a climb this long, discipline beats bravado. Anchor your effort to your FTP and aim to ride the sustained 6.03% sections just below threshold, leaving headroom for the 13.7% spikes that would otherwise blow your effort apart. If you do not know your threshold number, run a quick estimate with the FTP estimator before you plan a target. A useful mental model: hold a steady wattage on the average grade, allow short over-threshold surges on the steep ramps, then recover on the brief easings that account for the extra 111 m of total ascent. Over 21.8 km, going out too hard in the first few kilometres is the single most common way to arrive at 2089 m in survival mode.

Gearing

With 21.8 km at 6.03% and pitches to 13.7% at altitude, gear for the worst ramps, not the average. A compact 34-tooth chainring is the sensible front end. Pair it with at least a 34×32 for most riders, and strongly consider a 34×34 if you are not a lightweight or you want to protect your legs across the full 1314 m of gain. The lower ratio keeps your cadence up on the 13.7% sections so you spin rather than grind — a decisive advantage when the climb keeps going long after your legs would prefer it stopped.

Summary

Alto de San Pablo rewards patience: pace to your threshold, gear low for the steep ramps, and let the numbers do the rest across all 21.8 km. A category-1 test that earns its stripes.

Length: 21.8 km
Average gradient: 6.03%
Max gradient: 13.7%
Start: 775 m
Summit: 2089 m
Net gain: 1314 m
Total ascent: 1425 m
Category: 1