Alto del Rosario

Overview

Alto del Rosario is a Category 1 climb that packs a full day's suffering into 9.1 km. From a start elevation of 977 m it grinds upward to a 1733 m summit, a net gain of 756 m with 736 m of total ascent along the way. The headline number is the average gradient: 8.34% sustained across the entire climb. That is not a figure padded by a steep ramp and a flat run-out — it is a wall that rarely relents, and the 18.86% max gradient tells you the road has teeth where you least want them.

For context on categories, a Category 1 sits just below HC (hors catégorie, the hardest), and above the softer 2, 3 and 4 designations. At 9.1 km and 8.34%, Rosario earns that ranking honestly.

How the Gradient Unfolds

The shape here is defined by consistency punctuated by cruelty. With net gain (756 m) sitting a touch above total ascent (736 m), you can read the climb as almost entirely upward — there is little to no respite descending in the middle to reset your legs. Every metre you gain, you keep.

An 8.34% average across 9.1 km means the road hovers in the high single digits for long stretches. The 18.86% max gradient — well over double the average — signals at least one section that ramps far above cruising pitch. Those spikes are where cadence collapses and the climb is won or lost. Treat the average as your baseline and assume the road will periodically demand far more.

Pacing Notes

On a climb this sustained, pacing discipline beats bravado. The 9.1 km distance is long enough that going into the red early will cost you dearly before the 1733 m summit. Anchor your effort to your FTP: on a Category 1 grind, most riders should sit just below threshold and reserve headroom for the pitches approaching 18.86%.

If you do not know your threshold, run the numbers through the FTP estimator before you tackle the climb. Knowing your sustainable power turns an 8.34% average from a guessing game into a manageable target — you meter your effort to the grade rather than react to it.

When the road spikes, let cadence drop and torque carry you, then settle back to rhythm as soon as it eases. Riding the surges smoothly across all 9.1 km is faster than repeated matches burned at each steep ramp.

Gearing

An 8.34% average with 18.86% spikes is squarely compact-crank territory. A 34-tooth inner ring is the sensible front. For the cassette, most riders will want a 34×32 as a floor — that keeps cadence civil across the sustained grade. If you climb at a lower cadence, run less fitness on the day, or simply want insurance for the 18.86% pitches, a 34×34 buys crucial extra room. Over 9.1 km of near-constant climbing, an easier gear you rarely need beats a hard gear that grinds you down before the 1733 m top.

Summary

Alto del Rosario is a genuine Category 1 test: 9.1 km of sustained 8.34% climbing with a savage 18.86% max, hauling you 756 m up to 1733 m. Pace it against your FTP, gear low, and respect the ramps.

Length: 9.1 km
Average gradient: 8.34%
Max gradient: 18.86%
Start: 977 m
Summit: 1733 m
Net gain: 756 m
Total ascent: 736 m
Category: 1