Collado de Maz

Overview

Collado de Maz is an hors catégorie (HC) climb, the hardest classification there is before a road runs out of ways to punish you. Over 15.5 km it lifts you from a start elevation of 331 m to a summit at 1729 m, a net gain of 1398 m with 1322 m of total ascent along the way. The number that defines it is the average gradient: 8.99% sustained for the full distance. That is not a figure with soft stretches hiding behind it — a near-9% average over 15.5 km means the road tilts up and stays there, relentlessly, from bottom to top.

How the Gradient Unfolds

An 8.99% average across 15.5 km tells you most of the story: this is a long, uniformly steep wall rather than a climb of contrasting acts. The distinguishing feature is the max gradient of 21.09%, a ramp more than twice the average and steep enough to force even strong riders out of the saddle. Because the net gain (1398 m) exceeds the total ascent (1322 m), there is effectively no false-flat relief or descending to recover on — every metre gained is a metre climbed. Expect the hardest ramps to arrive when your legs are already loaded, and treat any brief easing as a chance to breathe rather than a chance to accelerate.

Pacing Notes

On a climb this sustained, pacing is everything. Anchor your effort to your FTP and hold a steady power target rather than chasing the gradient. At 8.99% average over 15.5 km, going even slightly too hard in the opening kilometres will cost you far more than it earns — the deficit compounds all the way to 1729 m. Save headroom for the 21.09% max ramp, where power spikes are unavoidable, then settle straight back to your target. If you are not sure where your threshold sits, run the numbers through the FTP estimator before you commit to a plan. The goal is a flat, repeatable effort you can defend for the full 1398 m of climbing.

Gearing

Do not underestimate this one. With an 8.99% average and pitches to 21.09%, a compact 34-tooth chainring paired with a wide cassette is the sensible baseline. A 34×32 will get most fit riders up the sustained sections, but on the steepest ramps — and this deep into 1398 m of gain — a 34×34 gives you the extra low gear to keep cadence alive instead of grinding to a stall. If your bike accepts it, err toward the easier 34×34. Spinning a small gear at a survivable cadence beats mashing a big one and blowing up before the summit.

Summary

Collado de Maz earns its HC label honestly: 15.5 km of near-constant 8.99% climbing, a 21.09% sting, and 1398 m of net gain to a 1729 m summit. Pace it conservatively, gear it low, and respect the length.

Length: 15.5 km
Average gradient: 8.99%
Max gradient: 21.09%
Start: 331 m
Summit: 1729 m
Net gain: 1398 m
Total ascent: 1322 m
Category: HC