Portella Blanca d'Andorra

Overview

Portella Blanca d'Andorra is a long-haul category-1 climb that trades ferocity for sheer duration. Over 27.4 km the road lifts you from a start elevation of 1272 m to a summit of 2471 m, a net gain of 1199 m at an average gradient of 4.37%. That average sounds gentle, and in isolation it is — but sustained for the better part of an hour and a half, at altitude, on a road that keeps climbing well past the point where most efforts would flatten out, it becomes a genuinely hard day. This is a diesel climb: one that rewards patience, steady output, and a willingness to keep the pressure on long after the initial excitement has worn off.

How the Gradient Unfolds

The single most important number here is the gap between net gain and total ascent. You climb 1199 m net, but the total ascent is 2330 m — meaning roughly 1131 m of climbing gets given back and re-earned across dips, false flats, and shallow descents along the way. In other words, the 4.37% average badly undersells the pitches you'll actually ride. The climbing is front-loaded and back-loaded rather than uniform: expect stretches noticeably steeper than the average, punctuated by rolling sections and brief descents that break your rhythm. On a climb this long, those interruptions are a double-edged sword — they offer recovery, but they also force you to repeatedly rebuild momentum from a standstill of effort.

Pacing Notes

The winning strategy on a 27.4 km climb is discipline. Anchor your effort to your FTP and resist the temptation to chase the steep early ramps — you have 1199 m of net gain to spend, and burning matches in the first third leaves nothing for the high-altitude finish near 2471 m, where thinner air quietly taxes every watt. Aim to ride the steady sections just under threshold and use the rolling dips as genuine recovery rather than acceleration zones. If you don't know your threshold number, run it through the FTP estimator before you go, then set a power or heart-rate ceiling you can hold for well over an hour. The riders who suffer least here are the ones who feel almost too comfortable in the opening 10 km.

Gearing

With 2330 m of total ascent to grind through and a summit at 2471 m, gear for endurance, not heroics. A compact 34-tooth chainring paired with a wide-range cassette is the sensible baseline. A 34×32 will carry most fit riders through the steeper-than-average pitches while keeping cadence high enough to protect the legs. If you're carrying fatigue, riding at altitude for the first time, or simply prefer to spin, step up to a 34×34 — that extra sprocket is cheap insurance on a climb where the difficulty is measured in time, not in a single wall. Preserving a smooth, high cadence is the surest way to arrive at the top with something left.

Summary

Portella Blanca d'Andorra is a category-1 test of stamina: long, high, and deceptively rolling, where the honest 2330 m of total ascent matters far more than the modest 4.37% average. Pace it patiently, gear it generously, and let the mountain reveal itself over all 27.4 km.

Length: 27.4 km
Average gradient: 4.37%
Max gradient: n/a
Start: 1272 m
Summit: 2471 m
Net gain: 1199 m
Total ascent: 2330 m
Category: 1