Collado Artaza

Overview

Collado Artaza is a long, serious category 1 climb that asks for patience before it asks for power. Over 17.5 km the road lifts from a start elevation of 733 m to a summit at 1828 m, a net elevation gain of 1095 m. The average gradient sits at 6.25%, which sounds moderate until you factor in the distance — this is the kind of effort where the clock, not any single ramp, decides how much it hurts. With a maximum gradient of 13.19% waiting somewhere along the way, there is enough variation to punish riders who treat the whole thing as one steady tempo.

How the Gradient Unfolds

The headline number is that 6.25% average, but the total ascent of 1076 m against a net gain of 1095 m tells you almost the entire climb is uphill with essentially no meaningful descending to break the rhythm. That is important: you rarely get a chance to freewheel and recover. Instead the pitch drifts above and below the average, and the standout figure is the 13.19% maximum. That is more than double the average, so the steepest section will feel like a wall relative to the surrounding grade. Expect long stretches near 6% that let you settle, punctuated by ramps that spike toward double digits. Riding the average blindly is a trap — the steep pitches will surge your effort well past what the 6.25% headline suggests.

Pacing Notes

At 17.5 km, this is a sustained-power test, so anchor your effort to your FTP rather than to how you feel in the opening kilometres. A climb this long rewards riders who start a touch conservatively and hold something in reserve for the 13.19% ramp. If you do not know your threshold precisely, run the FTP estimator first and set a target you can genuinely sustain for the full climb — roughly the time it takes to cover 17.5 km at your climbing pace. On the steepest pitch, let your effort rise briefly above threshold, then ease back to tempo once the grade relents rather than trying to hold the surge. Riding just under your ceiling on the shallow sections leaves headroom for the spikes, and with 1095 m of vertical to clear there is no shortcut around doing the work steadily.

Gearing

Gear for the maximum, not the average. A 13.19% ramp near the end of a 17.5 km climb, with 1095 m already in your legs, is exactly where an over-geared setup forces you to grind at low cadence. A compact 34-tooth inner ring paired with a 34×32 low gear is a sensible baseline for strong climbers who can sit and turn a steady tempo. If you prefer to spin, or you are pacing conservatively over the long haul, a 34×34 gives you that extra margin to keep cadence up on the 13.19% pitch without stalling. On a climb this length, the ability to keep the pedals moving smoothly matters more than raw gear ratio.

Summary

Collado Artaza is a genuine category 1 endurance climb: long, relentlessly uphill, and topped with a 13.19% sting that separates riders who paced well from those who did not. Gear conservatively, hold your threshold, and respect the distance.

Length: 17.5 km
Average gradient: 6.25%
Max gradient: 13.19%
Start: 733 m
Summit: 1828 m
Net gain: 1095 m
Total ascent: 1076 m
Category: 1