Col du Chaussy

What to Expect on the Col du Chaussy

The Col du Chaussy earns its Hors Catégorie rating honestly. At 10.1 km with an average gradient of 10.33%, there is no easy lower section to warm up on — the climb attacks from the moment it starts at 500 m elevation and does not relent until the summit at 1,544 m. That 1,044 m of net elevation gain over such a short distance puts it among the most demanding gradients in French alpine cycling.

The total ascent figure of 1,588 m — slightly higher than the net gain — indicates the road does not simply rise in a straight line. There are brief undulations where the gradient momentarily backs off before snapping back harder, which makes pacing by feel alone a recipe for blowing up.

How the Gradient Unfolds

The 10.33% average is already severe by any measure, but the 36.47% maximum gradient is the number that defines the character of this climb. A pitch of that steepness is not a ramp you muscle through; it is a technical obstacle requiring complete commitment and precise weight distribution to maintain traction and forward momentum.

Riders should anticipate the following broad pattern:

• Lower slopes: Gradient pressure is relentless from the start. There is no gentle introductory kilometre.
• Mid-section: The road averages above 10% throughout, meaning any section that feels manageable is simply less extreme than what surrounds it.
• Upper section and maximum ramp: The 36.47% maximum pitch likely appears in the upper portion of the climb. Approaching it with reserves spent is not a viable strategy.

Pacing

With an average gradient above 10% and a maximum nearly 36.5%, pacing errors are punished severely. The correct approach is to treat your FTP as a hard ceiling, not a target. Riding at or above threshold early will guarantee a collapse on the steeper pitches above.

• Start well below threshold. On a climb this steep, the natural instinct is to push hard to maintain speed — resist it.
• Use perceived exertion and power data together. Speed becomes almost meaningless at extreme gradients.
• On the maximum-gradient sections, staying seated is often more efficient for traction, but standing may be necessary to generate enough torque if your gearing runs out. Pick your approach before you arrive at the ramp.
• If you are unsure where your threshold sits before attempting this climb, use the FTP estimator to set a sensible power target.

Gearing

Do not underestimate the gearing requirement. A 36.47% gradient at any reasonable cadence demands an extremely low gear ratio. On a standard road groupset, even a compact chainset with a 34-tooth inner ring and an 11-32 cassette will feel limiting on the steepest section. Consider:

• Road: 34/34 minimum; a 34/36 or wider-range cassette is advisable.
• Gravel/adventure: Standard gravel gearing handles this more comfortably, but the gradient will still demand your lowest available ratio.
• Spin out the gear smoothly rather than mashing. Grinding a big gear at low cadence on a 36% slope leads to loss of traction and accelerated fatigue.

Summary

The Col du Chaussy is not a climb to tackle on a whim. 10.1 km, 10.33% average, 36.47% maximum, and 1,044 m of elevation gain from 500 m to 1,544 m — every one of those numbers points to the same conclusion: prepare thoroughly, gear appropriately, and pace conservatively from the base. There is no room to negotiate with a gradient this steep.