Colle della Vecchia

Overview

Colle della Vecchia is one of those climbs that reads like a typo. Over 16.7 km it averages 12.66%, hauling you from 317 m at the base to a summit of 2434 m. That is a net gain of 2117 m, with a total ascent of 2075 m once the minor undulations are added in. The category is HC — hors catégorie, the hardest rating there is, sitting above the numbered 1, 2, 3 and 4 climbs. Numbers like these put it in rarefied company: a double-digit average sustained for the better part of an hour, punctuated by a max gradient of 35.44% that borders on the walkable.

How the Gradient Unfolds

The defining feature here is relentlessness. A 12.66% average across 16.7 km means there is almost no recovery — few climbs of this length hold their gradient so high for so long. The 2117 m of vertical gain confirms it: you are climbing roughly the height of a serious alpine pass, but doing it on a wall rather than a series of switchbacks. The 35.44% max is the spike you must survive rather than pace. On ramps that steep, forward momentum and traction matter more than power discipline, and even a brief lapse in cadence can stall you. Between those spikes, expect long stretches that never dip into anything you would call easy. The climb finishes near 2434 m, high enough that thinning air adds its own tax to the final kilometres.

Pacing Notes

Treat this as an effort measured in hours, not minutes. Your sustainable ceiling is your FTP, and on a climb averaging 12.66% you will spend most of the ascent flirting with it. Go out too hard on the lower slopes and the 35.44% ramps higher up will end your day. Settle into a rhythm you can hold for the full 16.7 km, and let the steepest pitches spike your power briefly rather than trying to smooth them out. If you are unsure of your number, run it through the FTP estimator before you commit — pacing an HC climb blind is a fast route to blowing up.

Gearing

Gear for survival. On sustained 12.66% slopes with a 35.44% max, standard road gearing is not enough. A compact 34-tooth chainring paired with a 34×32 cassette is the sensible floor, and many riders will want to go further to a 34×34 to keep cadence alive on the worst ramps. If your setup allows an even wider range, take it — spinning a low gear beats grinding to a standstill on a wall this steep. Fresh legs and a light bike help, but gearing is what keeps you turning the pedals when the road tilts toward 35%.

Summary

Colle della Vecchia is a genuine HC monster: long, unrelenting, and punishingly steep from bottom to top. Respect the average, fear the max, and gear low.

Length: 16.7 km
Average gradient: 12.66%
Max gradient: 35.44%
Start: 317 m
Summit: 2434 m
Net gain: 2117 m
Total ascent: 2075 m
Category: HC