Somport

Overview

Somport is a hors catégorie (HC) climb, the hardest rung on the classification ladder above categories 1 through 4. The numbers explain why. Over 23.3 km the road climbs from 819 m at the base to a 2243 m summit, a net elevation gain of 1424 m at an average gradient of 6.11%. It is a long, high-altitude effort where the total ascent matches the net gain almost exactly, so once you start climbing you keep climbing. There is no rolling relief to hide in — this is a sustained haul that rewards patience over aggression.

How the Gradient Unfolds

A 6.11% average across 23.3 km sounds steady, and much of the climb is. But the 16.69% maximum tells you the road is not uniform. Expect long ramps sitting near the average, punctuated by steeper pinches where the gradient more than doubles. Because the climb gains 1424 m, the upper reaches sit well above 2000 m, where thinner air quietly shaves watts off your legs regardless of what the gradient reads. Treat the mid-section average as your baseline and the max as a warning: the steepest pitches will arrive when you are already deep into the effort, so keep something in reserve for them.

Pacing Notes

On a climb this long, pacing is everything. Anchor your effort to your FTP and hold a sustainable power well below threshold — a 23.3 km, 1424 m effort is measured in tens of minutes, not seconds, so riding it like a short climb guarantees a blow-up. If you do not know your threshold, run the numbers through the FTP estimator first, then set a target you can hold for the full duration. On the 16.69% pinches, let cadence drop and power spike briefly rather than surging early. The altitude near the 2243 m summit will make any over-pacing feel worse than the gradient alone would suggest, so err conservative in the opening kilometres.

Gearing

For an HC climb averaging 6.11% and topping out at 16.69%, gear low and gear with margin. A compact chainring is the sensible front end, and on the back you want plenty of range. A 34×32 will get most fit riders up the steady sections comfortably, but on the 16.69% ramps at altitude, near the top of a 1424 m ascent, a 34×34 gives you the extra bailout gear that keeps your cadence spinning instead of grinding to a stall. If your legs are fresh a 34×32 may be enough; if you are climbing this at the end of a long day, fit the 34×34 and thank yourself later.

Summary

Somport is a genuine HC test: 23.3 km of near-continuous climbing, a 6.11% average that hides 16.69% spikes, and a 1424 m gain that carries you to 2243 m of altitude. Pace it to your threshold, gear it low, and respect the length.

Length: 23.3 km
Average gradient: 6.11%
Max gradient: 16.69%
Start: 819 m
Summit: 2243 m
Net gain: 1424 m
Total ascent: 1424 m
Category: HC