Passo di Laroussa

Overview

Passo di Laroussa is a genuine hors catégorie climb, and the numbers leave no room for doubt. Over 13.9 km the road averages 10.99%, hauling you from a start elevation of 930 m to a summit at 2457 m. That is 1527 m of net elevation gain, with 1477 m of total ascent — meaning almost the entire climb is spent going up, with barely a metre of respite. There is no rolling approach to hide in here: the gradient is the story from the first pedal stroke to the last.

A double-digit average across nearly 14 km puts Laroussa in rare company. Most riders will spend the better part of an hour on this wall, and the altitude gain into the 2457 m summit thins the air as you climb. This is a climb to be respected long before you reach the steepest ramps.

How the Gradient Unfolds

The defining feature of Laroussa is relentlessness. With a 10.99% average sustained over 13.9 km, there are no genuine recovery zones. The gap between the 1527 m net gain and the 1477 m of total ascent is only 50 m, which tells you almost none of the route trends downhill — you are effectively climbing every single kilometre.

Expect the effort to feel remarkably even in its severity. Where many long climbs alternate steep pitches with flatter breathers, Laroussa holds its punishing slope throughout. Break it into thirds and each one demands the same discipline: settle in, hold a rhythm, and refuse to over-commit early. The summit sits at 2457 m, so the final third also carries the thin-air penalty of altitude on top of the gradient.

Pacing Notes

On a climb this sustained, pacing is everything. A 10.99% average for the best part of an hour means your effort should sit close to a level you can hold to the top — going into the red on the lower slopes will cost you dearly near 2457 m. Anchor your effort to your FTP and aim to ride the climb at a steady, sustainable fraction of it rather than surging.

If you are unsure of your current threshold, run the numbers through the FTP estimator before you tackle Laroussa, then translate that into a target you can defend across all 13.9 km. Consistency beats heroics here: the rider who paces the first two-thirds conservatively will pass the one who blew up chasing an early gap.

Gearing

Do not undergear this climb. A 10.99% average over 13.9 km, topping out at 2457 m, punishes anyone carrying too tall a bottom gear. For most riders a compact chainring paired with a wide-range cassette is the sensible minimum — a 34×32 will get you up, but only just, and it leaves little in reserve when fatigue sets in on the upper slopes.

If you have the option, favour a 34×34. That extra sprocket lowers your minimum cadence-friendly gear and lets you spin rather than grind through the sustained pitch, protecting your legs for the full 1527 m of climbing. On a wall like Laroussa, more range is always the safer choice.

Summary

Passo di Laroussa is an uncompromising HC climb: nearly 14 km of double-digit gradient with no shelter and a high-altitude finish. Pace it honestly, gear it generously, and treat every kilometre with respect.

Length: 13.9 km
Average gradient: 10.99%
Max gradient: n/a
Start: 930 m
Summit: 2457 m
Net gain: 1527 m
Total ascent: 1477 m
Category: HC