In the Cantabrian mountains, Los Machucos lives up to its Spanish nickname ‘rampas inhumanas’ — a wall that alternates deceptive flat stretches with ramps above 25%, among the hardest ever tackled by the Vuelta a España.
A short but extreme ascent
From Bustablado, it’s 6.8 km for 625 m of elevation gain, averaging 9.2%, but that average hides a much harsher reality: sections at 15-20%, with peaks of 26-28% in places, broken up by brief flatter stretches.
A recent Vuelta a España feature
Los Machucos has only been used twice by the Vuelta a España: in 2017, when Alberto Contador won at the summit after Stefan Denifl’s disqualification, one of the last great victories of his career; and again in 2019, when a young Tadej Pogačar beat Primož Roglič on these extreme slopes.
How to approach the ride
An extra-wide-range cassette is essential here, more so than anywhere else on this list, along with well-maintained brakes for the technical descent that follows an equally steep profile.
When to climb it
May to October: this mountain road can stay tricky after rain, a factor that matters even more than usual on gradients this steep.
Good to know
The pass’s local name, Collau Espina, marks the high point at 921 m; despite the modest altitude, the difficulty of Los Machucos rivals climbs far higher, a reputation built on gradient alone.