Colla Piana

Overview

Colla Piana is a category HC climb in France, one of the hardest classifications on the road. It runs 11.5 km from a start elevation of 920 m to a summit at 2,197 m, delivering a net elevation gain of 1,277 m. At an average gradient of 11.08%, it sits well into the range where the climb stays relentless from bottom to top rather than easing off in stretches.

The headline figure to sit with is the gap between net gain and total ascent. You climb 1,277 m net, but the road actually piles up 1,741 m of ascent — 464 m of that is re-climbing after short descents and dips. That undulation means the climb is harder than the net number suggests: every metre lost to a downhill has to be paid back with interest, and the repeated changes in rhythm tax the legs more than a single steady drag would.

How the Gradient Unfolds

An 11.08% average is punishing, but averages flatten the story. On a climb with this much undulation, the mean hides both the recovery dips and the ramps that run far steeper than 11%. Expect the gradient to swing hard rather than hold a line.

• Short flatter or descending sections where the road gives back a little — use them, but they inflate the total ascent figure.
• Repeated short climbs stacked back to back, each demanding a fresh surge of effort.
• Steep ramps well above the average, where the gradient spikes into double digits and forces you out of any comfortable rhythm.

Pacing Notes

On an undulating HC climb, chasing an even speed will bury you — the steep ramps would force efforts you cannot recover from before the next one. Pace to effort instead. Anchor your climb to your sustainable power output and hold a target you can carry for the full 11.5 km, letting your speed rise on the dips and fall on the ramps.

If you do not know that number, run the FTP estimator before you go. With 1,741 m of total ascent to absorb, starting a few percent too hard on the lower slopes will cost you badly in the final kilometres.

Gearing

At over 11% average with steeper ramps stacked on top, gearing is not optional — it governs whether you ride or walk. Fit a compact or sub-compact chainset and a wide-range cassette. A 34×32 is the sensible minimum here; a 34×34 gives you more room to spin the steepest pitches and protect your knees. Check your setup before the ride, not at the trailhead — swapping a cassette in the car park is a bad way to start an HC climb.

Summary

• Length: 11.5 km
• Average gradient: 11.08%
• Net elevation gain: 1,277 m
• Total ascent: 1,741 m
• Category: HC

Colla Piana is a genuine HC test: steep on average, steeper in places, and made harder by 464 m of hidden re-climbing. Pace it to effort, gear it for the ramps, and respect the total ascent over the net figure.