Collado de las Víboras

Overview

Collado de las Víboras is a category 1 climb that stretches 14.2 km and averages 6.71%. From a start elevation of 731 m it works steadily upward to a 1682 m summit, a net gain of 951 m. That length combined with a mid-6% average is exactly the profile that earns a climb its category 1 rating: long enough to hurt, steep enough to matter, and just short of the hors catégorie tier reserved for the truly monstrous ascents.

The numbers tell a clear story. With a total ascent of 928 m against a net gain of 951 m, the road climbs almost relentlessly. There is very little false-flat or descending to give the legs a break, so nearly every metre you gain is metre you have to earn under power.

How the Gradient Unfolds

Average gradient is a blunt instrument. The 6.71% mean sits comfortably in the range most trained riders can sustain, but the 10.55% maximum is the figure that reshapes your effort. When a climb tops out nearly 4% above its average, those steep pitches are not evenly distributed comfort — they are spikes that force your cadence down and your heart rate up.

Expect the gradient to breathe. Sections near or below the 6.71% average will feel like the "rhythm" part of the climb, while the pitches approaching 10.55% demand a deliberate shift of effort. Over 14.2 km, managing the swing between those two states is the whole game.

Pacing Notes

The right target for a climb this long is your sustainable threshold, not a heroic surge. Pace the bulk of the 14.2 km at an intensity you can hold, using your FTP as the anchor. If you do not have a current threshold figure, run the numbers through the FTP estimator before you plan the climb.

Ride the average-gradient sections a touch conservatively so you keep something in reserve for the 10.55% ramps. On those steep pitches, let your effort rise briefly above threshold rather than blowing your cadence apart trying to hold a fixed wattage. Over 951 m of climbing, small pacing errors compound — go out too hard in the first few kilometres and the back half of the climb will collect the debt with interest.

Gearing

For a 14.2 km effort at 6.71% average with ramps to 10.55%, gearing generously is the smart move. A compact 34-tooth inner chainring paired with a 34×32 low gear covers most riders comfortably on the average-gradient stretches and gives you a fighting cadence on the steep sections.

If you climb at lower cadence, carry extra weight, or simply want insurance for the 10.55% pitches near a 1682 m summit where the air is thinner, step up to 34×34. The wider ratio costs you nothing on the shallower ramps and buys real relief when the road kicks up.

Summary

Collado de las Víboras is a genuine category 1 test: 14.2 km, 6.71% average, and 951 m of net gain to a 1682 m summit, with pitches touching 10.55%. Pace it to threshold, gear it generously, and respect the length as much as the slope.

Length: 14.2 km
Average gradient: 6.71%
Max gradient: 10.55%
Start: 731 m
Summit: 1682 m
Net gain: 951 m
Total ascent: 928 m
Category: 1