Passo della Portula

Overview

Passo della Portula is a hors catégorie monster, the kind of climb that rewrites your idea of what "steep" means. Over 16.4 km it averages a brutal 10.44%, hauling you from a valley floor at 533 m up to a summit at 2245 m. That is a net elevation gain of 1712 m, with 1785 m of total ascent once you account for every rise and dip along the way. There is no easing into this one: an average above 10% sustained for well over an hour means the road almost never relents, and the 39.24% max gradient promises at least one moment that borders on the absurd.

How the Gradient Unfolds

The headline number to respect is the average: 10.44% is not a figure you meet on gentle roads. Because the mean sits this high across 16.4 km, the climb offers almost no true recovery. Where many long ascents hide flat false-flats that pull the average down, the small gap between net gain (1712 m) and total ascent (1785 m) — just 73 m of extra climbing from minor dips — tells you the profile is remarkably relentless and one-directional. The 39.24% max gradient is the sting in the tail of that arithmetic: a spike that far above the average means at least one ramp will force you out of the saddle or onto the rivet. Expect the pattern to be long, grinding slopes broken only by pitches that are even harder.

Pacing Notes

On a climb this steep and this long, discipline early is everything. The temptation on the lower slopes is to match the gradient with force; resist it. Your sustainable ceiling here should be anchored to your FTP — climbing 16.4 km at 10.44% will take most riders well past an hour, so aim to settle just below threshold and hold it. If you do not know your number, run the FTP estimator before you go, then budget your effort against that figure rather than against how you feel in the first kilometre. The 39.24% max ramp is where a blown pacing plan gets exposed: arrive there with matches to spare, not already redlined.

Gearing

Gear for the average, then gear again for the max. With a 10.44% mean over 16.4 km, a 34×32 is the sensible floor for strong climbers, but given the 39.24% spike and 1712 m of gain, most riders will be far happier on a 34×34 or an even wider ratio. The extra sprocket is not vanity — it is the difference between spinning through the steepest pitch and grinding to a track stand. If your setup allows anything easier than 34×34, take it here.

Summary

Passo della Portula is a pure HC test: long, unbroken, and savagely steep, with a maximum ramp that will be talked about long after the summit. Pace it against your FTP, gear low, and respect the average.

Length: 16.4 km
Average gradient: 10.44%
Max gradient: 39.24%
Start: 533 m
Summit: 2245 m
Net gain: 1712 m
Total ascent: 1785 m
Category: HC