Eth Portilhon

Overview

Eth Portilhon is a category 2 climb that stretches 14 km from a base at 597 m to a summit at 1302 m. On paper the 5.05% average gradient reads as steady and manageable, and for long stretches it is. But that number hides the climb's real character: a 20.83% maximum pitch that turns one section into a genuine test of legs and composure. The net elevation gain is 705 m, with 697 m of total ascent logged along the way, so nearly every metre you climb is a metre you keep. This is a climb that rewards riders who can hold a rhythm and still find a gear when the road rears up.

How the Gradient Unfolds

Averaged across 14 km, 5.05% is a gradient most trained riders can sit and spin. The challenge is that the slope is not evenly spread. With a maximum of 20.83%, the climb clearly stacks its difficulty into one or more short, brutal ramps that sit far above the average. Expect long tempo sections in the 4 to 6% range that let you settle, punctuated by a sharp pitch that spikes toward that 20.83% wall. The gap between the 5.05% average and the 20.83% max is roughly 15.78 percentage points, and that spread is exactly where riders get caught out. Ride the mellow kilometres too hard and you will have nothing left when the gradient jumps.

Pacing Notes

Because the difficulty is front-loaded into steep ramps rather than a relentless wall, pacing here is about restraint. Treat the shallow kilometres as recovery, not opportunity. Aim to climb the sustained sections at or just below your FTP, leaving a reserve for the 20.83% pitch where power spikes are unavoidable. Over 14 km at 5.05% you will be climbing for a meaningful chunk of time, so a blow-up early is expensive. If you do not know your threshold yet, run the numbers through the FTP estimator before you plan your effort. On the steep ramp, shift early, stay seated as long as traction allows, and let cadence drop rather than surging into the red.

Gearing

The 5.05% average does not demand exotic gearing, but the 20.83% max absolutely does. On a ramp that steep, an undergeared setup forces you into a grinding, muscular effort that torches your legs and destroys your rhythm. A compact 34-tooth chainring is the sensible front choice. Pair it with at least a 34×32 to give yourself a bail-out gear for the mellow-to-moderate slopes. For most riders tackling the 20.83% pitch, though, a 34×34 is the smarter call, buying you enough cadence to spin rather than lurch over the steepest metres. If your cassette allows it, err toward the easier ratio; you will never regret spare gears on a wall like this.

Summary

Eth Portilhon packs its 14 km into a deceptive 5.05% average with a sting of 20.83% waiting in the middle. Pace the shallow sections with discipline, save a match for the steep ramp, and gear low enough to keep spinning. Manage those two things and the 705 m of net gain from 597 m to 1302 m becomes a satisfying category 2 conquest rather than a slog.

Length: 14 km
Average gradient: 5.05%
Max gradient: 20.83%
Start: 597 m
Summit: 1302 m
Net gain: 705 m
Total ascent: 697 m
Category: 2