Colle Birrone

Overview

Colle Birrone is a long, Category 1 haul that rewards patience over punch. At 28.9 km, it is one of those climbs where the distance itself is the difficulty: you start at 373 m and finish at 1766 m, a net gain of 1393 m earned over the better part of an hour or more in the saddle. The average gradient of 4.82% sounds gentle on paper, and for long stretches it is — but that number hides a maximum pitch of 16.91%, steep enough to force you out of the saddle and rethink your effort entirely. Total ascent across the climb is 1383 m, close to the net figure, which tells you this is an honest, steadily rising road rather than a rollercoaster of dips and false flats.

How the Gradient Unfolds

The math is worth understanding before you turn a pedal. A 4.82% average over 28.9 km is a moderate slope you could theoretically settle into and never leave. The problem is the 16.91% maximum — that is more than three times the average. On a climb this long, a single ramp that steep bleeds disproportionate energy, and because the average stays modest, the road must be shallower than 4.82% elsewhere to compensate. Expect a mix of comfortable, tempo-friendly gradients punctuated by sharper kicks that arrive when your legs are already deep into the 1393 m of climbing. Treat the shallow sections as recovery, not as an excuse to burn matches.

Pacing Notes

On a climb of 28.9 km, pacing is everything. The single biggest mistake is riding the early, shallow slopes too hard and arriving at the steepest 16.91% ramp already over your limit. Anchor your effort to your FTP: aim to sit just below threshold on the average gradient and hold something in reserve for the steep pitches, where your speed drops and time-in-effort climbs. If you do not know your threshold number, run it through the FTP estimator first, then set a power or heart-rate ceiling you can defend for the full ascent. With 1393 m to gain, discipline in the first third pays off in the last.

Gearing

Gear for the maximum, not the average. A 4.82% mean is spinnable on almost anything, but the 16.91% pitch is where undergearing wrecks a ride. For most riders a compact 34-tooth chainring paired with a 34×32 low gear is the sensible baseline, giving you a workable cadence on the steep sections without grinding. If you climb at a lower cadence, carry extra fatigue, or simply want insurance across 28.9 km of climbing, step up to a 34×34. On a climb this long, the wider gear costs you nothing on the flatter grades and saves your knees on the ramp.

Summary

Colle Birrone is a distance climb with a sting: long enough to test your endurance, steep enough in one place to test your gearing and your patience. Pace it to your threshold, respect the steep pitch, and let the shallow sections do the recovering for you.

Length: 28.9 km
Average gradient: 4.82%
Max gradient: 16.91%
Start: 373 m
Summit: 1766 m
Net gain: 1393 m
Total ascent: 1383 m
Category: 1