Colle Carrel

Overview

Colle Carrel is one of those climbs whose numbers do the intimidating for you. Over just 9.9 km it averages 13.93%, a figure that sits far outside what most riders ever tackle for a sustained effort. From a start at 562 m it climbs to a summit of 1935 m, a net elevation gain of 1373 m packed into a distance many riders would consider a warm-up on flatter terrain. Rated HC — hors catégorie, the hardest classification above categories 1 through 4 — this is a climb defined by relentless steepness rather than length. The total ascent of 1340 m confirms there is almost no relief: the road simply points up and stays there.

How the Gradient Unfolds

The defining feature here is that the average and the difficulty are almost the same thing. A 13.93% mean over 9.9 km means there are no meaningful flat sections to recover on; even the "easier" stretches are climbing hard. The gradient peaks at a brutal 33.43%, a pitch steep enough that staying upright and keeping momentum becomes its own challenge. With the difference between the net gain of 1373 m and the total ascent of 1340 m being small, you can infer the road climbs almost continuously from bottom to top, without the descents or plateaus that break up longer passes. Expect the steepest ramps to force you out of any rhythm you've built, then dump you straight back onto another wall.

Pacing Notes

On a climb this steep, pacing is less about even splits and more about survival management. Your sustainable power on the day should sit around your FTP, but the 33.43% pitches will spike you well above it whether you like it or not — the trick is limiting how long you spend over threshold and recovering on the merely "hard" 13.93% sections. If you don't know your threshold, run the numbers through the FTP estimator before you commit, because getting your effort wrong early on a 9.9 km, 1373 m wall leaves nowhere to hide. Start conservatively; the summit at 1935 m is a long way up when the gradient never eases.

Gearing

Do not under-gear this climb. With a 13.93% average and ramps to 33.43%, a compact 34-tooth chainring paired with a wide cassette is the minimum sensible setup. A 34×32 is workable for strong climbers holding good cadence, but most riders will be far happier with a 34×34, and many would justifiably reach for even lower ratios given the 33.43% max. The extra range is not about comfort — it is about turning the pedals at all on the steepest pitches. Over 1373 m of near-continuous climbing, a bailout gear is the difference between riding and walking.

Summary

Colle Carrel is a short, savage HC climb where the gradient does all the work. Nearly 1400 m of ascent in under ten kilometres, with pitches that touch a third grade, make this a proper test of climbing strength and gear choice alike.

Length: 9.9 km
Average gradient: 13.93%
Max gradient: 33.43%
Start: 562 m
Summit: 1935 m
Net gain: 1373 m
Total ascent: 1340 m
Category: HC