Colle delle Miniere

Overview

Colle delle Miniere is an HC climb — hors catégorie, the hardest grade there is, above categories 1 through 4 — and the numbers explain why. Over 15.9 km the road climbs relentlessly at a 10.25% average gradient, hauling you from a start elevation of 1215 m to a summit at 2848 m. That is a net elevation gain of 1633 m, with 1656 m of total ascent once the minor undulations are added in. Almost every metre points uphill. This is not a climb with a runway; it starts hard and stays hard, finishing in genuinely thin air well above 2800 m.

How the Gradient Unfolds

A 10.25% average across 15.9 km is uncommon — most famous ascents sit several points lower — and the shape here is defined by how little relief there is. With total ascent (1656 m) sitting only 23 m above the net gain (1633 m), there are almost no descents or flat recovery breaks folded into the profile. The 23 m of "extra" climbing tells you the false-flats and dips are negligible; you are essentially climbing in one continuous direction for the full distance. The sting is the 38.7% max gradient, a wall so steep it dwarfs the already brutal average. Expect the road to lurch between merely severe and near-vertical, with the steepest pitches demanding you stay seated and grind rather than attack.

Pacing Notes

On a climb this long and this steep, pacing is everything. Ride the first few kilometres well below what feels sustainable — the 2848 m summit means thinning oxygen will quietly erode your power near the top, so the effort you hold at the base will feel harder as you climb. Anchor your pace to your FTP and hold just under it; the 10.25% average leaves no room to recover from a blow-up. If you do not know your threshold, run the numbers through the FTP estimator before you commit. When the gradient spikes toward 38.7%, accept that you will briefly exceed threshold — there is no gearing that erases a wall that steep — then settle back down the moment the pitch relents.

Gearing

Gear for survival, not pride. At a 10.25% average over 15.9 km, with ramps to 38.7%, you want the lowest gearing you can bolt on. A compact 34-tooth chainring paired with a 34×32 cassette is the sensible minimum for strong climbers, but on the steepest sections most riders will be grateful for a 34×34. If your bike accepts it, go lower still — a 38.7% ramp will punish anything taller. Fresh legs might spin 34×32 comfortably; deep into 1633 m of climbing, that same gear can feel impossibly stiff, which is exactly why the extra range of 34×34 earns its place.

Summary

Colle delle Miniere is an uncompromising HC test: long, viciously steep, and topping out in high-altitude air with no meaningful respite anywhere on its 15.9 km. Pace conservatively, gear low, and respect the walls.

Length: 15.9 km
Average gradient: 10.25%
Max gradient: 38.7%
Start: 1215 m
Summit: 2848 m
Net gain: 1633 m
Total ascent: 1656 m
Category: HC