Col du Giétro

Overview

The Col du Giétro is a long-haul category-1 climb that trades brutality for endurance. Over its full 34.4 km it averages a modest-looking 4.35%, but that number hides a lot: this is a climb measured in hours, not minutes. From a valley start at 488 m it works its way up to a 1984 m summit, a net gain of 1496 m spread across more than a marathon's worth of road.

At this length, the Giétro is less a single wall than a sustained effort. The average gradient never feels punishing on its own, yet the sheer distance means fatigue is the real adversary. Add a 14.75% maximum pitch lurking somewhere in the profile, and you have a climb that rewards patience and punishes anyone who treats the early slopes like a warm-up sprint.

How the Gradient Unfolds

The headline figure is deceptive. A 4.35% average across 34.4 km implies long stretches of shallow gradient stitched together with steeper ramps. The gap between the 4.35% mean and the 14.75% maximum tells you the road is uneven: expect false flats and gentle drags interrupted by sharp kicks that spike well above threshold.

That 1496 m of net gain, against a total ascent of 1525 m, reveals something else: there are roughly 29 m of small descents or dips baked into the route. On a climb this long, those brief downhills are a gift for the legs but a trap for rhythm, since every metre lost has to be regained. Plan to ride the average, not the peaks.

Pacing Notes

On a climb of this duration, pacing is everything. Your FTP is the anchor: hold a sustainable percentage of it through the shallow sections and resist the urge to chase the steeper ramps. Over 34.4 km, minutes spent burning matches early cost you far more later.

If you are unsure of your threshold, run the numbers through the FTP estimator before you commit to a target. Aim to sit comfortably below threshold on the 4.35% stretches, then allow controlled surges over the 14.75% pitches — spinning, not grinding, through the worst of them. The 29 m of dips scattered across the total ascent are your chance to soft-pedal and recover.

Gearing

Length is the argument for easier gearing here. Even though 4.35% is manageable, holding it for 34.4 km with a 14.75% max means you want spinning gears in reserve. A compact 34-tooth chainring paired with a wide-range cassette is the right foundation.

A 34×32 is a sensible baseline for strong riders who can hold a steady tempo. But given the distance and the total ascent of 1525 m, most riders will thank themselves for a 34×34, which keeps cadence high on the steep ramps without forcing a slow, muscle-shredding grind. When in doubt on a climb this long, go easier.

Summary

The Col du Giétro is an endurance climb defined by its length rather than its slope. A patient rider who paces to FTP and gears for the long haul will summit strong; anyone who mistakes the gentle average for an easy day will be undone by the distance.

Length: 34.4 km
Average gradient: 4.35%
Max gradient: 14.75%
Start: 488 m
Summit: 1984 m
Net gain: 1496 m
Total ascent: 1525 m
Category: 1