Puerto de San Lorenzo

Overview

Puerto de San Lorenzo is a Hors Catégorie (HC) climb in Spain. It runs 8.6 km from a start elevation of 495 m to a summit at 1342 m, for a net elevation gain of 847 m. At an average gradient of 9.84%, this is a short climb by HC standards but a relentlessly steep one — there is very little of it that lets you sit up.

The number that reframes the effort is total ascent: 1421 m of climbing packed into a route that only lifts you 847 m net. That 574 m gap means the road is not a clean ramp — it undulates, giving back nearly 574 m of descent that you then have to reclaim. Every metre you lose on a dip is a metre you pay for again. Treat the 847 m net figure as the accounting summary and the 1421 m total as the real workload your legs will feel.

How the Gradient Unfolds

A 9.84% average on an undulating profile is deceptive: the descents and flatter links drag the mean down, which means the climbing pitches sit well above 9.84%. Where the road goes up, it goes up hard. The recovery you get is real, but it is bought back immediately by the next ramp.

• Short flatter or descending sections that briefly drop the gradient and let you spin
• Repeated pitches well steeper than the 9.84% average, since the mean is diluted by those recoveries
• Little rhythm — expect to change cadence and effort constantly rather than settling in
• The steepest ramps demanding out-of-saddle efforts on the day

Pacing Notes

On a smooth climb you would ride even effort and let speed float. Here, with 1421 m of total ascent against 847 m net, even-speed pacing is a trap: holding a target speed on the steep pitches would spike you far above your sustainable power output and leave nothing for the next ramp. Pace by effort, not by the clock or the display speed.

Anchor your steep-section effort to a hard but repeatable ceiling, then actively soft-pedal the flatter and descending links to recover — don't hammer them. Know your ceiling before you start; run the numbers through the FTP estimator so you're pacing against a real figure, not a guess.

Gearing

Gearing is governed by the steepest pitches, not the average, and on this climb those pitches are severe. A compact (34-tooth inner) or sub-compact chainset paired with a wide-range cassette is the right call — think 34×32 or 34×34 to keep a turnable cadence when the road kicks up. Undergearing here means grinding at low cadence on the worst ramps, which burns matches fast. Check your chainset and cassette before the ride; you do not want to discover you're a couple of teeth short partway up an HC wall.

Summary

• Length: 8.6 km
• Average gradient: 9.84%
• Net elevation gain: 847 m
• Total ascent: 1421 m
• Category: HC

Puerto de San Lorenzo is short but uncompromising: an HC climb that averages nearly 10% and, thanks to 574 m of hidden descent, makes you climb 1421 m to gain 847. Pace by effort, gear low, and respect the undulation.