Col du Grand Cucheron

Overview

Col du Grand Cucheron is a Category 1 climb in France, running 20 km from a valley start at 289 m to a summit at 1227 m. Over that distance it delivers a net elevation gain of 938 m at an average gradient of 4.7%. On paper that average reads as a steady tempo climb, but the number flattens out a profile that is anything but uniform.

The clearest signal is the gap between the net gain and the total ascent. You climb 938 m net, but the route racks up 1493 m of total ascent — 555 m of that is climbing you do more than once, giving it back on descents and false flats before earning it again. That undulation means the effort is lumpier than a 4.7% average suggests: you spend real energy on pitches that don't show up in the net figure, and momentum is repeatedly broken.

How the Gradient Unfolds

The 4.7% average is a blend, not a description. With 555 m of undulation folded in, long stretches sit well below average — even downhill — which mathematically forces other sections far above it. The single steepest ramp bites at 24.91%, a wall that has nothing to do with the tempo feel of the average.

• Flatter and recovery sections, including descents, that pull the average down and let you reset
• Repeated short climbs stacked through the middle, the source of the extra ascent
• A steepest ramp touching 24.91% that demands you're already in your easiest gear

Pacing Notes

On an undulating climb like this, even-speed pacing is a trap: holding a fixed pace over the 24.91% ramp would spike you far past threshold, while the descents waste it. Pace to even effort instead. Anchor your ceiling to your sustainable power output and let speed float — slow and steady over the steep pitches, roll the descents without chasing watts. If you don't know your ceiling, set it with the FTP estimator before you commit to a number on the road.

Gearing

Your gearing is governed by the steepest gradient, not the average. A 24.91% ramp will overwhelm a standard road setup. Run a compact or sub-compact chainset with a wide-range cassette — something like 34×32 or 34×34 — so you can spin the steepest section instead of grinding it and blowing up. Check your chainset and cassette before the ride; the summit is a poor place to discover you're over-geared.

Summary

• Length: 20 km
• Average gradient: 4.7%
• Maximum gradient: 24.91%
• Net elevation gain: 938 m
• Total ascent: 1493 m
• Category: 1

Col du Grand Cucheron is a Category 1 climb that rewards discipline over ambition. Respect the undulation, pace to effort, and gear for the steepest ramp — do that, and the 938 m come without a blow-up.