col de Bretaye

Overview

Col de Bretaye sits in Switzerland and earns its HC (hors catégorie) rating without any argument. It runs 16.6 km from a start elevation of 389 m to a summit at 1,807 m, delivering a net elevation gain of 1,418 m. That is a long, sustained effort at altitude, and the category tells you what the numbers confirm: this is a climb that outlasts most riders' patience before it outlasts their legs.

The headline figure is the net gain of 1,418 m, but the total ascent is 1,609 m. That 191 m gap is undulation — climbing you do that gets undone by short descents and false flats along the way. It matters because every one of those extra metres is real work that never shows up in the net figure. You climb, you give some back, you climb again. Plan your effort around 1,609 m of ascent, not 1,418 m, or you will be under-fuelled and under-paced by the top.

How the Gradient Unfolds

The 8.55% average is a useful summary and a poor guide. Averages get diluted by the flatter, undulating sections, which means the climbing pitches sit well above 8.55% to compensate. The steepest ramp hits 30.02% — a wall that no cadence-based pacing survives. Expect the gradient to swing hard rather than settle.

• Flatter and recovery sections where the false flats and short descents create that 191 m of extra ascent — use them, but don't relax the whole way
• Repeated short climbs that stack up between the recovery stretches, each one steeper than the average implies
• One brutal ramp at 30.02% that demands your lowest gear and an out-of-saddle grind

Pacing Notes

On a smooth climb you can hold even effort and let speed drift. Bretaye's undulation breaks that. Even-speed pacing here is a trap: matching your valley-floor speed on the 30% ramp would blow you apart. Ride even-effort instead — hold a steady sustainable power output and let your speed collapse on the ramps and recover on the flats. Know that number before you start; the FTP estimator will get you a working figure. On the recovery sections, resist the urge to push back to threshold — bank the rest for the next wall.

Gearing

A 30.02% pitch governs your entire setup. A standard chainset will leave you stalled and walking. Fit a compact (50/34) or sub-compact chainset paired with a wide-range cassette — 34×32 at the absolute minimum, 34×34 if you can run it, and lower still if your groupset allows. Check your setup before the ride, not at the trailhead. Confirm the rear derailleur clears the largest sprocket and the chain is long enough. Getting this wrong on a 16.6 km HC climb is a very long day.

Summary

• Length: 16.6 km
• Average gradient: 8.55%
• Maximum gradient: 30.02%
• Net elevation gain: 1,418 m
• Total ascent: 1,609 m
• Category: HC

Col de Bretaye is a long, undulating HC effort that rewards patience and punishes poor gearing. Ride it on even effort, gear for the 30% ramp, and account for all 1,609 m of climbing — not just the net.