Puerto de Ondárroa

Overview

Puerto de Ondárroa is a category 4 climb that stretches 7.8 km and lifts you from just 6 m above sea level to a summit at 244 m. On paper the headline figure is gentle: the average gradient sits at 3.07%, which places this firmly in the "long but never brutal" bracket. The net elevation gain is 238 m, while the recorded total ascent is 221 m, a small gap that tells you the road doesn't simply point uphill the whole way. Instead, it rolls, dips, and recovers as it climbs. That combination makes Ondárroa an inviting effort for riders building toward steeper category 1 and HC efforts, and a genuinely rhythmic tempo climb for everyone else.

How the Gradient Unfolds

With 238 m of net gain spread across 7.8 km, the climb averages a shade over 3%, but averages hide the texture. The 7.87% maximum gradient is more than double the mean, so expect at least one meaningful pinch where the road bites back. Because total ascent (221 m) is slightly less than net gain (238 m), the profile is not perfectly monotonic — there are short flattening or descending sections that let you catch your breath and shift up. The smart way to read the shape: long stretches near or below the 3.07% average, punctuated by ramps climbing toward that 7.87% ceiling. Ride the easy parts with intent and treat the steep pinch as the one place you'll spend a match.

Pacing Notes

On a climb this length and gradient, pacing is about restraint, not heroics. Aim to hold a steady effort just under threshold on the shallow sections, saving headroom for the ramp toward 7.87%. Anchoring your effort to your FTP keeps you honest: on the flatter grades you can sit comfortably below it, then briefly push over it on the steep pinch without blowing up. If you don't know your number, run the numbers through the FTP estimator first, then set a target power you can sustain for the full 7.8 km. Because the average is only 3.07%, momentum matters — don't let your speed sag on the recovery sections, since carrying pace there costs far less than surging on the climbs.

Gearing

Ondárroa doesn't demand extreme gearing, but comfort pays over 7.8 km. A compact 34-tooth inner chainring paired with a wide-range cassette gives you plenty of options. For most riders a 34×32 low gear is more than enough to spin the 7.87% pinch without grinding, keeping cadence high and your legs fresh for the shallower kilometres. If you're carrying fatigue, riding loaded, or simply prefer to twiddle, a 34×34 adds a touch more relief on the steepest ramp and lets you stay seated throughout. Either way, the goal is a cadence you can hold steady rather than a gear you have to muscle.

Summary

Puerto de Ondárroa is a friendly, rhythmic category 4 climb: long enough to matter, shallow enough to enjoy, with a single steep pinch to keep you honest. Pace it steadily, carry momentum through the recoveries, and you'll crest the 244 m summit feeling strong.

Length: 7.8 km
Average gradient: 3.07%
Max gradient: 7.87%
Start: 6 m
Summit: 244 m
Net gain: 238 m
Total ascent: 221 m
Category: 4