Alto del Retiro

Overview

Alto del Retiro is a short climb that punches far above its distance. At just 3 km, it looks harmless on paper, but a 12.23% average gradient turns those kilometres into a sustained fight against gravity. You start at 934 m and top out at 1302 m, a net gain of 368 m packed into a span most riders would cover in a gentle warm-up elsewhere. The category-1 rating is earned entirely through steepness rather than length, and it will expose any weakness in your climbing rhythm within the first few minutes.

How the Gradient Unfolds

The defining feature here is that there is nowhere to hide. A 12.23% average over 3 km means the road rarely dips into anything you could call recovery terrain, and the 16.57% maximum tells you the steepest ramp sits more than four points above an already savage mean. Expect the pitch to swing between merely hard and genuinely brutal, with the gradient clawing toward that 16.57% peak on the sharpest sections. Because the total ascent of 338 m is slightly less than the net gain of 368 m, the profile is almost uniformly upward, without meaningful descents to break the effort. In practical terms: settle in, because the climb does not.

Pacing Notes

On a climb this steep and this short, the temptation is to attack from the base. Resist it. The smartest approach is to hold an effort just under your threshold and let the gradient do the damage to your rivals instead of to you. Anchor your pacing to your FTP: riding the lower ramps a touch below it banks the headroom you will need when the road tilts toward 16.57%. If you are unsure where that ceiling sits, run the numbers through the FTP estimator before you commit to a target. Over 3 km, a steady, slightly conservative first half almost always beats a hot start that unravels near the top.

Gearing

Gearing is where Alto del Retiro is won or lost. A 12.23% average sustained for 3 km, with pitches to 16.57%, demands a compact setup and a generous cassette. A 34×32 is the sensible baseline for strong climbers who can turn a bigger gear without grinding to a halt. But for most riders, and especially on the steepest ramps, a 34×34 gives you the extra spin needed to keep cadence up and your knees intact. If your bike accepts it, err toward the easier 34×34 here — the extra range costs you nothing on a climb with no flat sections to spin out on, and it buys real insurance against the 16.57% wall.

Summary

Alto del Retiro is a compact, uncompromising category-1 test: 3 km of near-constant climbing at 12.23%, spiking to 16.57%, lifting you 368 m from 934 m to 1302 m. Come with low gearing, disciplined pacing, and respect for how quickly a short climb can hurt.

Length: 3 km
Average gradient: 12.23%
Max gradient: 16.57%
Start: 934 m
Summit: 1302 m
Net gain: 368 m
Total ascent: 338 m
Category: 1