Col de Grimone

What Kind of Climb Is Col de Grimone?

Col de Grimone sits in the Drôme département of southeastern France, a category 2 climb that earns its classification more through treachery than raw statistics. The headline numbers look manageable — 10 km, 5.07% average gradient, 954 m of total ascent — but averages flatter to deceive here. A maximum gradient of 24.6% confirms that somewhere on this road, the climb turns savage, and arriving at that ramp with no fuel left or the wrong gear is a costly mistake.

Gradient Profile: Bottom to Summit

The climb starts at 798 m and tops out at 1,305 m, so the vertical gain is steady but not relentless when spread across 10 km. At an honest average of 5.07%, most of the road sits in a range that a trained rider can sustain at a reasonable tempo.

The 24.6% maximum, however, represents a section that bears no resemblance to that average. Gradients in that range demand either a very low gear or a very short effort — ideally both. Without knowing the exact placement of the ramp, the safest approach is to treat the entire upper half of the climb conservatively, arriving at any steep pinch with power in reserve rather than already in the red.

Key Gradient Reference Points

• Start elevation: 798 m
• Summit elevation: 1,305 m
• Total ascent: 954 m
• Length: 10 km
• Average gradient: 5.07%
• Maximum gradient: 24.6%
• Category: 2

Pacing Notes

A 5% average over 10 km sits in a range where many riders are tempted to push hard from the base. Resist that. The 24.6% maximum means gradient variance is extreme, and variable-gradient climbs punish anyone who rides the flat or gentle sections above their sustainable threshold.

The practical approach is to pace the early and moderate sections at or just below your functional threshold power, keeping something back for the steep pitches. On ramps approaching 25%, momentum management matters — carry what speed you can into the base of the ramp, shift before cadence collapses, and grind through rather than surging.

If you want to estimate what effort is sustainable across 10 km of climbing, the FTP estimator can give you a power target to structure your effort around.

Gearing Recommendations

For a climb with a maximum gradient of 24.6%, a compact chainset (50/34) with an 11-32 or 11-34 cassette is the practical choice for most riders. Attempting a 24%-plus ramp on a standard 53/39 with a tight cassette puts you in a position where you either mash a gear that kills the legs or come to a stop.

• Compact + 32 or 34 sprocket: handles the steep pitches without blowing up the climb
• Standard chainset: workable only if you are a strong climber comfortable at low cadence on very steep grades
• 1x setups: viable with a wide-range cassette (40t or 42t), but confirm your range before committing to the descent on the other side

Bottom Line

Col de Grimone is a category 2 climb that rewards patience and punishes optimism. The 5.07% average suggests a steady grind; the 24.6% maximum guarantees at least one moment where the road stops cooperating. Treat it as an uneven climb, gear for the worst section, and pace the early kilometres with the steep ramp firmly in mind.