Alto de Silverio

Overview

Alto de Silverio is an hors catégorie monster, the kind of climb that earns its rank not through a single vicious wall but through relentless, sustained accumulation. Over 22.3 km it gains 1648 m of net elevation, dragging you from a start at 1730 m all the way to a summit at 3378 m. The average gradient of 7.39% sounds civil enough on paper, but stretched across 22.3 km it becomes a war of attrition. The total ascent of 1645 m — nearly identical to the net gain — tells you this is an honest climb: it points up and stays there, with almost nothing given back along the way.

How the Gradient Unfolds

The defining feature here is length married to steepness. A 7.39% average would be manageable over a few kilometres; over 22.3 km it is genuinely enormous. That average also hides the sting: the maximum gradient hits 22.18%, roughly three times the average, so somewhere in these 22.3 km the road rears up into a pitch that will have you out of the saddle and wrestling. Because the net gain (1648 m) and total ascent (1645 m) differ by only 3 m, there are effectively no descents or flat recovery zones to reset your legs. Every metre of the 1648 m climbed is metre you keep. Add the altitude — finishing at 3378 m — and the thinning air compounds every percent of gradient in the final kilometres.

Pacing Notes

Discipline is everything on a climb this long. Ride the first two-thirds well within yourself, targeting an effort you can hold at or just below your FTP — a 22.3 km effort is not the place to burn matches early. The 22.18% max gradient is the one spot where you may briefly exceed threshold; everywhere else, keep the power steady and let the climb come to you. Remember that the summit sits at 3378 m, where reduced oxygen will quietly clip your sustainable power, so bank a small buffer for the top. If you are unsure what wattage to hold across 22.3 km, run your numbers through the FTP estimator before you commit to a pace, then hold it honestly from the base at 1730 m.

Gearing

Gear for survival, not pride. With 1648 m of climbing at 7.39% and ramps touching 22.18%, most riders will want the deepest bailout ratio they can fit. A compact 34-tooth chainring paired with a 34×32 will cover the sustained sections, but on a climb this long — especially in thin air near 3378 m — a 34×34 gives you the extra spin that keeps cadence up and knees intact when the gradient bites. If your frame accepts it, favour the 34×34; the ability to sit and spin through the 22.18% pitch is worth far more than a slightly closer ratio spacing across 22.3 km.

Summary

Alto de Silverio is a true hors catégorie test: long, steep, high, and unrelenting from 1730 m to 3378 m. Pace it patiently, gear it generously, and respect the altitude, and its 1648 m of climbing becomes one of the great rewards in cycling.

Length: 22.3 km
Average gradient: 7.39%
Max gradient: 22.18%
Start: 1730 m
Summit: 3378 m
Net gain: 1648 m
Total ascent: 1645 m
Category: HC