Colle Vallonetto

Overview

Colle Vallonetto is a hors catégorie (HC) monster, the kind of climb that measures your day rather than punctuates it. It runs 27.6 km from a valley floor at 756 m up to a summit of 2555 m, a net gain of 1799 m. The average gradient of 6.52% sounds civil on paper, but sustained over nearly 28 kilometers it becomes an exercise in patience and self-management. This is a climb of scale: at just under an hour and a half of climbing for most riders, it demands respect long before the road tilts hardest.

How the Gradient Unfolds

Averages hide the story, and Vallonetto's 6.52% mean conceals a maximum pitch of 15.41% — more than double the average. That spread tells you the road is not metronomic. Expect stretches that sit comfortably under the average, offering rare recovery, offset by ramps that spike toward the 15.41% ceiling and force you out of rhythm. The total ascent of 1803 m slightly exceeds the 1799 m net gain, meaning there are small dips or false flats along the way where you briefly stop climbing before the wall resumes. Read the road ahead: the steepest sections are where riders who went out too hard come undone.

Pacing Notes

On a climb this long, pacing is everything. Anchor your effort to a power target rather than to how you feel in the first few kilometers, when fresh legs lie to you. A sustainable tempo just below your FTP is the goal for the long 6.52% grind, with the discipline to keep something in reserve for the 15.41% ramps. Surging on the steep pitches and then blowing up costs far more time than climbing them steadily. If you are unsure of your threshold, run the numbers through the FTP estimator before you commit to a target — nearly 28 kilometers of climbing is not the place to guess. Fuel early and often; at this duration, calories are as important as watts.

Gearing

Gear for the maximum, not the average. The 15.41% ramps late in a 27.6 km effort will overwhelm anything too tall, so bring a compact and a wide cassette. A 34×32 is the sensible baseline for strong climbers, giving you a manageable spin on the steeper pitches. If you weigh more, plan to ride the full distance at threshold, or simply want to protect your knees over a summit finish at 2555 m, step up to a 34×34. The extra range costs nothing on the shallow sections and buys you a survivable cadence when the road stands up. On an HC climb, undergearing is the most common and most punishing mistake.

Summary

Colle Vallonetto is a genuine HC test: long, high, and topped with pitches steep enough to break a poorly paced ride. Respect the distance, gear generously, and hold your power steady, and the summit at 2555 m rewards the discipline.

Length: 27.6 km
Average gradient: 6.52%
Max gradient: 15.41%
Start: 756 m
Summit: 2555 m
Net gain: 1799 m
Total ascent: 1803 m
Category: HC