Passo dei Gatòn

Overview

Passo dei Gatòn is one of those climbs that leaves no room for negotiation. Over 16.9 km it averages 9.29%, dragging you from a valley floor at 62 m up to a summit of 1634 m. That is 1572 m of net elevation gain, with 1581 m of total ascent once the handful of flatter recoveries are accounted for. There is barely daylight between those two figures, which tells you almost everything: this road climbs, and then it keeps climbing, with next to nothing given back.

The classification is HC — hors catégorie, the hardest rung on the ladder above categories 1 through 4. On paper a sub-10% average over nearly 17 km already earns that label comfortably. In the legs, it earns it several times over.

How the Gradient Unfolds

The defining feature here is consistency of punishment. A 9.29% average across 16.9 km is not built from a savage wall followed by easy spinning; the near-identical net gain (1572 m) and total ascent (1581 m) prove that the climb almost never flattens or descends. You gain roughly 93 metres of altitude for every kilometre ridden, start to finish.

Think of the profile as a long, tilted ramp rather than a staircase. From 62 m the road tips up early and holds a punishing pitch through the middle third, where fatigue starts stacking. The final kilometres toward 1634 m offer no reprieve — with only 9 m separating total ascent from net gain, there is essentially no rolling terrain to hide in. Whatever gradient you are riding at the bottom is close to the gradient you will still be riding near the top.

Pacing Notes

On a climb this uniform, pacing is everything. Pick an effort you can genuinely sustain for the full duration, because there are no flat sections to recover on and no descents to soft-pedal. A good rule of thumb is to settle just below your threshold and hold it — riders who go out hard on the lower slopes pay for it dearly across the back half.

Your FTP is the number that matters most here. Knowing it lets you translate a target percentage into a power ceiling you can defend for 16.9 km. If you are unsure where yours sits, run the numbers through the FTP estimator before you commit to a plan. Aim to arrive at the steepest sustained stretches with something in reserve rather than clawing back time you never had.

Gearing

Do not under-gear this one. A 9.29% average sustained for the better part of an hour will expose any compromise in your cassette. A compact chainset paired with a 34×32 is the sensible minimum for strong climbers, but for most riders — and anyone carrying fatigue or extra weight — a 34×34 is the smarter call. That extra sprocket buys you a lower cadence floor precisely where the road refuses to ease, letting you spin rather than grind toward 1634 m. When in doubt on an HC climb like this, take the easier gear.

Summary

Passo dei Gatòn is a pure, unrelenting HC ascent: long, steep, and almost entirely without let-up. Respect the average, gear low, and pace it from the first metre.

Length: 16.9 km
Average gradient: 9.29%
Max gradient: n/a
Start: 62 m
Summit: 1634 m
Net gain: 1572 m
Total ascent: 1581 m
Category: HC