Colletto

Overview

Colletto is a long, category 1 ascent that rewards patience over aggression. At 20.2 km with an average gradient of 5.15%, it never lets you settle into a rhythm you can coast through, yet it rarely tips into the truly desperate — with one glaring exception. You start at 589 m and finish at 1627 m, a net gain of 1038 m, with 1013 m of total ascent logged along the way. That distance places it firmly among the endurance climbs: the sort where your legs are fine at kilometre five and the question is whether your pacing was honest at kilometre fifteen.

How the Gradient Unfolds

The headline number, 5.15%, is deceptively mild for a climb of this length. Because the net gain (1038 m) sits above the total ascent (1013 m), the road climbs almost continuously — there is little in the way of false flat or descent to recover on. That matters more than the average suggests: 20.2 km of relentless, always-upward grade wears riders down slowly rather than dramatically.

The defining feature is the maximum gradient of 19.35%. A ramp nearly four times steeper than the average will not just hurt — it will force a decision. If you have burned your reserves smoothing over the earlier kilometres, that wall arrives like a bill you forgot you signed. Treat the average as a budget and the 19.35% pitch as the moment you cannot be overdrawn.

Pacing Notes

For a climb this long, the winning strategy is discipline. Ride the shallower opening slopes noticeably below your threshold — you should feel like you are leaving something on the table, because you are saving it for the steep pitch and the thin air near 1627 m. Anchor your effort to your FTP: on a 20.2 km climb, sustaining even a few percent above threshold is a trap that only reveals itself late. Aim to sit comfortably under it for the bulk of the ascent, then spend freely on the 19.35% ramp.

If you are unsure where your ceiling sits, run the numbers through the FTP estimator before you commit to a race pace. Knowing your sustainable wattage turns a guessing game into a plan.

Gearing

Gear for the wall, not the average. A climb that averages 5.15% but spikes to 19.35% punishes anyone who brings a cassette built for rolling terrain. A compact 34-tooth inner chainring paired with a 34×32 setup is the sensible baseline for most riders tackling Colletto, giving you a low enough ratio to spin the steady sections without grinding.

But for that 19.35% pitch — especially after 15-plus kilometres of climbing in your legs — a 34×34 is the smarter insurance. The extra tooth keeps your cadence alive when the road stands up, and preserving cadence over 20.2 km is what keeps the climb sustainable rather than survival.

Summary

Colletto is a genuine endurance test: 20.2 km of near-continuous climbing at 5.15%, defined by a single ferocious 19.35% pitch that demands you arrive with reserves intact. Pace it honestly, gear it generously, and the 1038 m of vertical becomes a rhythm rather than a reckoning.

Length: 20.2 km
Average gradient: 5.15%
Max gradient: 19.35%
Start: 589 m
Summit: 1627 m
Net gain: 1038 m
Total ascent: 1013 m
Category: 1