Alto del Cármen

Overview

Alto del Cármen is a hors catégorie (HC) climb that demands respect from the first pedal stroke. Over 18.2 km it lifts you from a start elevation of 840 m to a summit of 2384 m — a net elevation gain of 1544 m. The average gradient sits at a punishing 8.47%, and it rarely lets up long enough for you to catch your breath. This is a long, sustained effort where patience matters more than raw power.

At nearly two vertical kilometers of climbing packed into a single ascent, the numbers alone explain the HC classification. There are harder categories than 1, 2, 3, and 4 — this is the top of that scale — and Alto del Cármen earns it through relentless length and steepness in combination.

How the Gradient Unfolds

The defining feature here is consistency at a brutal average. An 8.47% mean across 18.2 km means there is very little genuine recovery. Where lesser climbs offer flat interludes to spin the legs, this one keeps the pressure on.

The max gradient of 20.04% is the sting in the tail — or wherever it lands. A ramp more than twice the average will spike your heart rate and force you out of any comfortable rhythm. Expect the pitch to swing well above and below 8.47%, and plan your effort around surviving those double-digit ramps rather than the average.

Note that the total ascent of 1518 m is slightly less than the net elevation gain of 1544 m — a 26 m difference — which tells you the route is essentially all-up, with almost no descending to reset your legs.

Pacing Notes

Discipline wins this climb. With an 8.47% average over 18.2 km, going into the red early is the fastest way to blow apart before the summit. Anchor your effort to your FTP and hold a wattage you can sustain for the full duration — likely 30 to 60 minutes depending on your fitness.

If you don't know your threshold, run the numbers through the FTP estimator before you commit. On the 20.04% max ramp, allow yourself a brief surge above threshold, then settle back the moment the road eases. Treat every pitch above 8.47% as borrowed effort you'll have to repay.

Gearing

Do not under-gear this climb. With sustained 8.47% and a 20.04% max, most riders will want the widest ratios they can fit. A compact 34-tooth chainring paired with a 34×32 cassette is a sensible baseline for strong climbers, but the extra insurance of a 34×34 will keep your cadence alive on the steepest ramps and preserve your legs across the full 18.2 km.

If you can run 34×34, take it. On a climb of this length, spinning a lower gear at a higher cadence protects you from the muscular fatigue that ends efforts early. Grinding a heavy gear here is a recipe for cramping before 2384 m.

Summary

Alto del Cármen is a genuine HC test: long, steep, and unforgiving from 840 m all the way to 2384 m. Pace to your threshold, gear low, and respect the 20.04% ramp. Get those three right and the summit is yours.

Length: 18.2 km
Average gradient: 8.47%
Max gradient: 20.04%
Start: 840 m
Summit: 2384 m
Net gain: 1544 m
Total ascent: 1518 m
Category: HC