Alto de Bustablao

Overview

Alto de Bustablao is a category 2 climb that stretches across 15.4 km, lifting you from a starting elevation of just 30 m to a summit at 670 m. On paper the numbers look gentle: an average gradient of 4.15% and a net elevation gain of 640 m. But averages lie on climbs like this one. With a max gradient of 15.79% lurking somewhere in the middle, Bustablao is a climb of contrasts — long stretches where you can find a rhythm, punctuated by ramps steep enough to blow that rhythm apart. It is the kind of ascent that rewards patience and punishes anyone who mistakes a low average for an easy day.

How the Gradient Unfolds

The gap between the 4.15% average and the 15.79% maximum tells you almost everything about the shape of this climb. Over 15.4 km, a steady 4.15% would be a pleasant tempo effort. Instead, that average is diluted by flatter, faster sections that let the gradient hide its teeth. The recorded total ascent of 626 m sits just below the 640 m net gain, which means there is very little false flat or descending — the road climbs almost the entire way, but unevenly. Expect the pitch to sag toward single digits in places, then rear up toward that 15.79% wall where the road bites hardest. Reading the climb correctly means saving something for those spikes rather than burning it on the shallower approaches.

Pacing Notes

Pace Bustablao off your sustainable power, not off the terrain in front of you. Because the climb averages 4.15% over 15.4 km, most of it should sit comfortably below your FTP — treat the flatter kilometers as recovery and hold power in reserve for the steep ramps. When the gradient jumps toward 15.79%, you will inevitably surge above threshold; the goal is to keep those surges short and controlled rather than letting them stack into a blowup. If you are unsure of your numbers, run them through the FTP estimator before you ride so you know exactly what ceiling you are working under across a 640 m climb.

Gearing

The 15.79% maximum is the number that dictates your setup. A compact chainring paired with a wide-range cassette is the sensible choice here. A 34×32 will get most fit riders over the steepest pitches, but on a 15.4 km climb where the legs are already 640 m of elevation into the effort, the extra insurance of a 34×34 is worth it. That lower ratio lets you keep the cadence spinning through the 15.79% ramps instead of grinding to a near-standstill. If in doubt, gear easier — you can always stay seated and comfortable, but you can't manufacture a bailout gear you didn't bring.

Summary

Alto de Bustablao is a deceptive category 2 test: forgiving on average, brutal in its spikes. Respect the 15.79% ramps, pace off your threshold across the full 15.4 km, and bring gearing you won't regret near the 670 m summit.

Length: 15.4 km
Average gradient: 4.15%
Max gradient: 15.79%
Start: 30 m
Summit: 670 m
Net gain: 640 m
Total ascent: 626 m
Category: 2