Passo della Portela

Overview

The Passo della Portela is a genuine hors catégorie (HC) monster, the hardest rung on the climbing ladder before you run out of categories entirely. Over 15.3 km it drags you from a valley floor at 197 m up to a summit of 1770 m, a net gain of 1573 m. The average gradient sits at a brutal 10.3%, and it steepens to a maximum of 15.64% where the road pinches hardest. This is not a climb you survive on fitness alone — it demands a plan, the right gears, and the discipline to hold something back for the top.

How the Gradient Unfolds

A 10.3% average across 15.3 km is relentless by any measure. There is very little relief written into these numbers: the total ascent of 1535 m is only 38 m shy of the 1573 m net gain, which tells you the road climbs almost continuously with barely any downhill or flat to break rhythm. In practice that means the double-digit average is not hiding a couple of savage walls stitched between rest sections — it is a sustained, grinding wall of a climb. The 15.64% maximum is the sharpest bite, likely on a switchback or an exposed pitch, but the story here is consistency: you will be leaning on the pedals from the 197 m base all the way to 1770 m.

Pacing Notes

On a climb this long and this steep, pacing is everything. Anchor your effort to your FTP rather than to how you feel in the first kilometre, because a 10.3% average will happily let you blow up early. If you do not know your number, run through the FTP estimator before you commit to this one. A sensible target for most riders is to sit just under threshold on the steadier stretches and let the effort creep only where the gradient forces it toward 15.64%. Resist surging out of every corner — with 1573 m of climbing ahead, every matched acceleration is energy you will beg for near the summit. Break the 15.3 km into thirds and reassess your legs at each mark.

Gearing

Do not under-gear this one. With a 10.3% average and ramps to 15.64%, a compact 34-tooth chainring paired with a wide cassette is the minimum sensible setup. A 34×32 is workable if you are strong and light, but for most riders on an HC climb of this length a 34×34 buys you the extra cadence to spin rather than grind through the steepest metres. If your groupset allows an even larger sprocket, use it — the goal is to keep your legs turning across all 1535 m of ascent, not to muscle a heavy gear and cook yourself before the top.

Summary

The Passo della Portela earns its HC label honestly: long, steep, and almost entirely uphill, with no soft numbers anywhere in its profile. Gear low, pace off your FTP, and treat the full 15.3 km with respect.

Length: 15.3 km
Average gradient: 10.3%
Max gradient: 15.64%
Start: 197 m
Summit: 1770 m
Net gain: 1573 m
Total ascent: 1535 m
Category: HC