Col des Brosses

Overview

Col des Brosses is a Category 2 climb in France that earns its classification through sustained length rather than relentless steepness — at least on paper. The 9.9 km route rises 760 m from a start elevation of 287 m to a summit at 862 m, averaging 5.79% across the full distance. That average is workmanlike, but the maximum gradient of 19.02% signals that this climb is not uniformly paced. Somewhere on the road between base and summit, the terrain turns sharply upward and demands respect.

Gradient Profile

The average of 5.79% over 9.9 km places the bulk of the climb in a range that experienced riders can sustain at threshold for extended periods. However, the gap between that average and the 19.02% maximum is large — roughly 13 percentage points — which tells you the climb is not steady. Expect sections that feel almost rolling or false-flat, followed by concentrated ramps that push well into double-digit gradients.

The 19.02% maximum is steep enough to force most riders out of the saddle regardless of gearing. At that pitch, traction, weight distribution, and cadence management all become active concerns, not afterthoughts.

What to Expect Section by Section

• Lower slopes: Starting at 287 m, the early kilometres at an average consistent with the overall mean give legs time to settle. Resist any temptation to push hard here — the brutal ramps are ahead.
• Mid-climb: This is where irregular gradient behaviour typically concentrates. Sections easing off are followed by sharp spikes. Treat easier passages as active recovery, not an invitation to accelerate.
• Upper slopes approaching 862 m: Summit approaches on climbs with high max-gradient figures often hold their hardest ramps for the final kilometres. Keep something in reserve.

Pacing Notes

With 760 m of total ascent and a 5.79% average, Col des Brosses is well within the range where power-based pacing pays dividends. If you have an FTP reference, consider targeting 75–85% of that figure for the sustained sections, with a clear understanding that the 19.02% ramps will briefly spike your output regardless of intent. Fighting to hold a power number through a 19% wall is counterproductive — shift early, spin through it, and reset on the other side.

For pacing strategy built around your current fitness, use the FTP Estimator before planning your effort.

Gearing Recommendations

A 9.9 km climb with a near-19% maximum is not the place to rely on a standard road compact if your legs are already tired from a longer route. Practical guidance:

• Compact chainset (50/34) with an 11-32 or 11-34 cassette will handle the steep ramps without forcing a grinding cadence that wrecks the rest of your climb.
• Semi-compact (52/36) is viable for stronger riders who can maintain 70+ rpm on steep pitches, but leaves little margin.
• 1x drivetrains with a wide-range cassette (10-42 or 10-46) remove front-shifting complexity — useful when ramps arrive suddenly.

If you're unsure how gearing choices affect sustainable gradient, the gradient and gearing glossary offers useful context on the relationship between cadence, power, and sustainable effort.

Summary

Col des Brosses is a Category 2 climb that rewards patience and punishes early aggression. Its 5.79% average is manageable; its 19.02% maximum is not. Respect the spread between those two numbers, gear appropriately, and pace the first half conservatively enough that the upper ramps don't end your day early.