Colle Costapiana

Overview

Colle Costapiana is an hors catégorie climb, the hardest grade on the road, and its profile earns every letter of that HC label. Over 13.3 km it averages a relentless 9.62%, dragging you from a start elevation of 1030 m up to a summit at 2312 m. That is 1282 m of net elevation gain and 1257 m of total ascent, meaning there is almost no respite built into the road — what goes up simply keeps going up. This is a climb that begins already high in the mountains and finishes higher still, in thin air where sustained power gets harder to hold.

How the Gradient Unfolds

The defining number here is the average: 9.62% held across the full 13.3 km. Very few climbs stay that steep for that long, and there is little in the way of flat recovery to hide behind. The near-identical figures for net gain (1282 m) and total ascent (1257 m) confirm it — the road barely descends anywhere, so you are climbing almost the entire distance. Then there is the maximum: 23.24%. A ramp that steep is more than double the average, a wall that will spike your heart rate and force you out of any comfortable rhythm. Expect the gradient to pulse between merciless and savage rather than easing off.

Pacing Notes

On a climb this long and steep, discipline beats bravado. Anchor your effort to your FTP and hold a percentage you know you can sustain for the better part of an hour, because at 9.62% average over 13.3 km there is no coasting to recover a blown match. If you are unsure of your threshold number, run the FTP estimator before you commit to a target. The real danger is the 23.24% max ramp: resist the urge to power over it and instead let your cadence drop, spinning what you can rather than burying yourself. At a summit of 2312 m the altitude will quietly clip your ceiling, so pace conservatively early and keep something in reserve for the final, thinner-air kilometres.

Gearing

Gear this one generously. With a 9.62% average and pitches touching 23.24%, most riders will want the lowest ratio they can get. A compact 34-tooth chainring paired with a 34×32 cassette is the sensible baseline, and if your legs or your target power say otherwise, size up to 34×34 for extra margin on the steepest ramps. On a 13.3 km wall, easier gearing is not weakness — it lets you protect your cadence, spread the load, and keep your effort under threshold all the way to 2312 m.

Summary

Colle Costapiana is a genuine HC test: long, unbroken, and viciously steep from bottom to top, finishing in high mountain air. Respect the average, fear the max, and gear low.

Length: 13.3 km
Average gradient: 9.62%
Max gradient: 23.24%
Start: 1030 m
Summit: 2312 m
Net gain: 1282 m
Total ascent: 1257 m
Category: HC