Col de Grosse Pierre

Overview

The Col de Grosse Pierre sits in France as a Category 3 climb — modest on paper, deceptive in practice. Eight kilometres from base to summit, 684 metres of total ascent, and an average gradient of 4.97% suggest something manageable. The 17.7% maximum gradient tells a different story. This is a climb that rewards patience and punishes riders who treat the average as a reliable guide to effort.

How the Numbers Stack Up

• Length: 8 km
• Total ascent: 684 m
• Average gradient: 4.97%
• Maximum gradient: 17.7%
• Category: 3
• Start elevation: 569 m
• Summit elevation: 964 m

The gap between average (4.97%) and maximum (17.7%) is the critical detail. A difference of nearly 13 percentage points means the road is not evenly pitched. Somewhere on those 8 km there is at least one ramp that is more than three times as steep as the mean gradient. Riders who pace off the average will be caught badly out of position when that ramp arrives.

How the Gradient Unfolds

With a 684-metre total ascent across 8 km, the climb averages close to 85 metres of vertical gain per kilometre — consistent with the ~5% mean. The presence of a 17.7% maximum implies concentrated hard sections bookended by shallower stretches. Expect the lower slopes to feel comfortable, possibly even inviting you to push harder than is wise. The steeper pitches tend to cluster in the middle or upper third of climbs with this profile shape, though the exact location of the maximum ramp is something to scout before racing.

The start elevation of 569 m means altitude is not a significant physiological factor. Oxygen availability at the summit (964 m) remains close to sea level norms, so breathing difficulty from thin air should not feature in your pacing calculation.

Pacing Strategy

For a Category 3 effort, most trained riders will complete this in a single sustained effort rather than treating it as a time-trial interval. The key is not to let the early shallow gradients pull you above your sustainable power.

Recommended approach:

• Establish a power target based on your FTP before the climb. Given the average gradient and category, an effort in the 75–85% FTP range suits the lower and flatter sections.
• Identify the steep ramp(s) in advance if possible. When the gradient spikes toward 17.7%, allow power to rise naturally rather than forcing a dig — the steepness will do the work of slowing you anyway.
• Do not accelerate on shallow sections to compensate for slow progress on steep ones. Distribute effort, not speed.
• If you are racing, conserve enough to push the final kilometre toward the summit at 964 m.

Use the FTP estimator to confirm your current threshold power before dialling in targets.

Gearing Notes

The 17.7% maximum gradient is the governing factor for gearing selection. On a climb with a near-5% average you might be tempted to run a standard or mid-compact setup, but the maximum ramp demands adequate low gearing.

• A compact chainset (50/34 or 46/30) paired with an 11-32 or 11-34 cassette is appropriate for most riders.
• Heavier riders or those with a lower FTP relative to body weight should lean toward the larger cassette.
• At 17.7% there is no benefit in grinding a big gear — cadence collapse accelerates fatigue in the hip flexors and lower back far faster than the aerobic cost of spinning a lower ratio.

Summary

The Col de Grosse Pierre cycling climb is a Category 3 that earns its grade through irregularity rather than sustained brutality. Eight kilometres, 684 metres of gain, and a maximum ramp of 17.7% make it the kind of climb that exposes riders who rely on feel alone. Discipline early, correct gearing, and a clear power target will see you over the summit at 964 m with something left.