Passo di Bondione

Overview

Passo di Bondione is a hors catégorie climb that hides nothing. Over 12.4 km it averages a punishing 9.37%, dragging you from a 755 m start to a 1917 m summit. That is 1162 m of net elevation gain — but the road banks up 1651 m in total ascent, meaning there are pitches where you claw back the same metres you briefly gave away. There is no gentle valley approach here. From the moment the gradient bites, this is a sustained, high-percentage effort that demands respect from the first pedal stroke.

How the Gradient Unfolds

The single most important number is the average: 9.37% held across 12.4 km. On most climbs an average like that would be softened by flatter recovery stretches, but the gap between a 1162 m net gain and 1651 m of total ascent tells the real story. Roughly 489 m of extra climbing is buried in short dips and re-ascents, so the road rears back up harder than the average implies to compensate. Expect long ramps well above the 9.37% mean, punctuated by pinches that break your rhythm. There is nowhere to freewheel and recover — the shape of this climb is relentless from 755 m all the way to 1917 m.

Pacing Notes

Pace this like the HC monster it is. With a 9.37% average over 12.4 km, going into the red early is the classic mistake — the summit at 1917 m is a long way from the start. Anchor your effort to your FTP and hold a steady, sustainable power rather than chasing the steepest ramps. If you do not know your threshold, run the numbers through the FTP estimator before you attempt it, then ride the lower pitches slightly under threshold so you have something left when the road kicks back up. Banking those 1162 m of net gain is about consistency, not heroics.

Gearing

On a 12.4 km wall averaging 9.37%, gearing is not a luxury — it is survival. A compact 34-tooth chainring is the starting point. Pair it with at least a 34×32 for the steadier sections, but given that 1651 m of total ascent packed into 12.4 km, most riders will be far happier with a 34×34. The extra range keeps your cadence up on the ramps that punch above the average, protecting your legs across the full 1162 m of gain. If your bike accepts an even wider cassette, take it — nobody regrets an easier gear on an HC climb.

Summary

Passo di Bondione is a benchmark HC ascent: 12.4 km, 9.37% average, and no relief from 755 m to 1917 m. Respect the numbers, pace off your threshold, and gear low. Do that, and 1162 m of net climbing becomes a summit worth savouring.

Length: 12.4 km
Average gradient: 9.37%
Max gradient: n/a
Start: 755 m
Summit: 1917 m
Net gain: 1162 m
Total ascent: 1651 m
Category: HC