Ovronnaz

Overview

Ovronnaz is a hors catégorie (HC) climb, the hardest classification there is, and the numbers explain why. Over just 8.1 km the road averages 11.03%, dragging you from a start elevation of 475 m up to a summit at 1363 m. That is 888 m of net elevation gain packed into a climb barely longer than eight kilometres — the kind of density that leaves no room to recover. There are no long false flats to hide in, no gentle run-in to warm the legs. From the moment the gradient bites, it stays bitten. If you have circled this one on a route, treat it with the respect an HC label demands: it will punish a bad pace far more than it rewards a brave one.

How the Gradient Unfolds

An 11.03% average is already severe, but averages flatten out the story. The headline is the 21.09% maximum gradient — nearly double the average — which tells you the climb hides ramps steep enough to slow you to a near-standstill. With total ascent measured at 858 m against 888 m of net gain, there is almost no descending or flattening anywhere on the route; the road simply goes up, and up steeply. Expect the profile to feel relentless rather than rhythmic: stretches around the average that already burn, punctuated by walls pushing toward that 21% ceiling. The gap between 11.03% and 21.09% is roughly ten percentage points, and every one of those points is a moment where cadence collapses and the effort spikes. Plan your energy around the spikes, not the average.

Pacing Notes

On a climb this steep and this short, discipline early is everything. Anchor your effort to your FTP and hold the first kilometres in check — the 21.09% ramps will demand surges no matter how smoothly you ride, so you want reserve in the tank for them rather than burning matches on the opening slopes. If you do not know your threshold, run the numbers through the FTP estimator before you commit to a target, because guessing wrong on an 8.1 km wall at 11.03% average is unforgiving. Aim to arrive at each steep pitch with something left, spin through it, then settle back to a sustainable rhythm on the sections nearer the average.

Gearing

Do not under-gear this one. With an 11.03% average and a 21.09% maximum, a compact 34-tooth chainring paired with a wide cassette is the minimum sensible setup. A 34×32 will get most fit riders up the sections around the average, but the ramps toward 21% are where it runs out of teeth — on those pitches you will be grinding a cadence that shreds the legs. If your bike accepts it, a 34×34 is the smarter choice for Ovronnaz, giving you a lower bailout gear to spin the steepest walls rather than muscle them. On an HC climb, easier gearing is not weakness; it is what keeps you turning the pedals to the summit.

Summary

Ovronnaz earns its HC status the honest way: short, savagely steep, and unrelenting from bottom to top. Gear low, pace conservatively, and save something for the 21.09% ramps.

Length: 8.1 km
Average gradient: 11.03%
Max gradient: 21.09%
Start: 475 m
Summit: 1363 m
Net gain: 888 m
Total ascent: 858 m
Category: HC