Colle Larissa

Overview

Colle Larissa is a hors catégorie (HC) climb, the hardest rung on the classification ladder, and its numbers explain why. Over 23.6 km the road lifts you from 344 m at the base to a 2580 m summit, a net gain of 2236 m at an average gradient of 9.46%. Very few paved climbs sustain a near-double-digit average across such a distance. This is not a climb that eases you in and rewards you at the end; it is a relentless, high-altitude effort that demands respect from the first pedal stroke.

How the Gradient Unfolds

The defining feature of Larissa is that its average of 9.46% is punishingly high for its 23.6 km length, so there is nowhere meaningful to recover. Total ascent measures 2228 m against a net gain of 2236 m, a difference of just 8 m — which tells you the road climbs almost continuously, with virtually no descending or flat respite to break the rhythm. The gradient peaks at 22.91%, more than double the average, so expect sharp ramps that force you out of any comfortable cadence. Between those spikes the road rarely relents below the average for long. Plan for a grind that gets harder as thinning air near the 2580 m summit compounds the sustained steepness.

Pacing Notes

On a climb this long and steep, pacing is everything. Ride the opening kilometres well within yourself — the average of 9.46% will feel deceptively manageable when fresh, but it accumulates. Anchor your effort to your FTP and aim to hold a sustainable percentage of it rather than chasing the wheel in front. If you are unsure of your threshold, run the numbers through the FTP estimator before you commit to a target power. Treat the 22.91% ramps as short surges to survive, not to attack; drop your cadence, stay seated where possible, and settle back into your target as soon as the gradient relaxes. With 2236 m of climbing ahead, discipline in the first third pays off in the final third.

Gearing

Do not under-gear this one. With a 9.46% average stretched over 23.6 km and pitches touching 22.91%, you want the widest range you can fit. A compact 34-tooth chainring paired with a 34×32 cassette is the sensible minimum for strong climbers, giving you a low bailout for the sustained middle section. For most riders, and for anyone carrying fatigue toward the 2580 m summit, step up to a 34×34 — that extra sprocket is the difference between spinning and grinding to a halt on the steepest ramps. When a climb gains 2236 m almost without pause, easier gearing is not a weakness; it is what keeps your cadence and your legs alive to the top.

Summary

Colle Larissa is one of the genuine giants: 23.6 km of near-continuous climbing at 9.46%, topping out at 2580 m after 2236 m of net ascent. Pace it patiently, gear it generously, and respect the altitude.

Length: 23.6 km
Average gradient: 9.46%
Max gradient: 22.91%
Start: 344 m
Summit: 2580 m
Net gain: 2236 m
Total ascent: 2228 m
Category: HC