Colle di Ciamporino

Overview

Colle di Ciamporino is a genuine hors catégorie (HC) test — the hardest rating a climb can carry, sitting above categories 1 through 4. Over 21.9 km it hauls you from a start elevation of 304 m up to a summit at 2290 m, a net elevation gain of 1986 m. The average gradient is a relentless 9.07%, and the road spikes to a savage 35.38% at its steepest. This is not a climb you ride into by accident; it is a long, sustained, high-mountain effort that rewards patience and punishes anyone who starts too hard.

How the Gradient Unfolds

The defining number here is the average: 9.07% held across 21.9 km. That is brutally consistent for a climb of this length, and it means there are few genuine recovery stretches to hide in. Total ascent measured along the road is 1949 m — slightly less than the 1986 m net gain, which tells you the profile climbs almost monotonically, with negligible descending or flat relief to break the rhythm. The 35.38% max gradient is the sting in the tail: even if it is a short pitch, a ramp that steep against an already-loaded set of legs can force a walk if you have misjudged your effort. Expect the climb to feel like one long wall broken by ramps that lean well beyond the average.

Pacing Notes

On a climb this long and steep, pacing is everything. Anchor your effort to your FTP and hold a sustainable percentage of it from the base — most riders target a fraction of threshold they can defend for the better part of an hour or more, because at 21.9 km and 9.07% you will be climbing for a long time. If you do not know your threshold, estimate it first with the FTP estimator. The steepest ramps toward the 35.38% max will drag your power spikes upward whether you like it or not, so bank a little headroom on the shallower sections rather than emptying the tank early. Ride the average, survive the ramps.

Gearing

Gear for the pitches, not the average. With sustained 9.07% grades and a 35.38% max, a compact 34-tooth chainring paired with a wide cassette is the sensible baseline. A 34×32 is the minimum most fit riders should bring; if you weigh more, ride at a steadier tempo, or simply want to spin the steepest ramps rather than grind them, step up to a 34×34 (or wider still). The extra range on the 34×34 buys you cadence when the road tilts past 20%, and on a 1986 m climb, protecting your legs early pays dividends near the 2290 m summit.

Summary

Colle di Ciamporino is an HC climb that earns its rating: long, high, and unrelentingly steep, topping out at 2290 m after 21.9 km of 9.07% averages and ramps to 35.38%. Bring low gears, a disciplined pacing plan, and respect for the altitude.

Length: 21.9 km
Average gradient: 9.07%
Max gradient: 35.38%
Start: 304 m
Summit: 2290 m
Net gain: 1986 m
Total ascent: 1949 m
Category: HC