Colle Scarassan

Overview

Colle Scarassan is a hors catégorie climb, the hardest rating on the scale that runs HC, 1, 2, 3, 4. It covers 17.8 km at an average gradient of 6.7%, lifting you from a start elevation of just 36 m to a summit at 1231 m. That works out to 1195 m of net elevation gain, with 1199 m of total ascent once the minor undulations are added in. The headline number, though, is the maximum gradient: 28.03%. A wall that steep on a climb already this long is what pushes Scarassan firmly into HC territory. This is not a climb you survive on fitness alone — it demands respect from the first pedal stroke.

How the Gradient Unfolds

The 6.7% average is honest but misleading, as averages always are on a climb with a 28.03% pitch buried in it. Over 17.8 km you gain 1195 m of height, so the mean tells you the effort is sustained rather than punchy. But the gap between 6.7% average and 28.03% maximum — more than 21 percentage points — signals a climb of uneven character. Expect stretches that sit near or below the average, giving your legs a fleeting chance to recover, broken by ramps that spike far beyond anything you can pace steadily. The final 1195 m of vertical is earned unevenly, and the steepest sections will decide how your ride is remembered.

Pacing Notes

On a climb this long, discipline beats bravado. Anchor your effort to your FTP and hold something in reserve for the ramps toward 28.03%, where power alone won't save you — cadence and momentum will. If you don't know your threshold yet, run the numbers through the FTP estimator before you commit to a pacing plan. Aim to ride the shallower sections a touch below threshold so you have headroom when the gradient bites. Nearly 18 km of climbing punishes anyone who goes out hot in the opening kilometres; the smart move is to treat the first two-thirds as setup for the brutal pitches that define the top.

Gearing

With a maximum gradient of 28.03% and 17.8 km of climbing to grind through, gear low and gear again. A compact 34-tooth chainring paired with a wide cassette is the minimum sensible setup here. A 34×32 will get most fit riders up the sustained 6.7% sections, but on the ramps toward 28% you will wish for more. If your derailleur allows it, run a 34×34 — that extra sprocket is the difference between spinning and stalling when the road stands up. Over 1195 m of net gain, protecting your knees and cadence matters more than pride.

Summary

Colle Scarassan is a long, uneven HC climb that rewards patience and punishes the impatient. Pace to your threshold, gear low, and save your matches for the 28.03% ramps.

Length: 17.8 km
Average gradient: 6.7%
Max gradient: 28.03%
Start: 36 m
Summit: 1231 m
Net gain: 1195 m
Total ascent: 1199 m
Category: HC