Col du Bez

Overview

The Col du Bez is a Category 1 climb in France that covers 7.5 km from base to summit, gaining 927 metres of total ascent. Starting at 649 metres elevation, the road rises to a summit of 1,231 metres. That average gradient of 7.76% places it firmly in demanding territory — the kind of number that punishes riders who go out too hard in the opening kilometres.

What sets this climb apart from others in its category is the maximum recorded gradient of 45.39%. That figure is not a typo. At its steepest, the Col du Bez throws a ramp at riders that borders on unrideable for most people without specific preparation. Understanding where that spike sits — and managing your legs accordingly — is the central tactical challenge of this climb.

How the Gradient Unfolds

With a 7.5 km length and 927 metres of total ascent, the maths alone signals a climb that is consistently steep rather than gently rolling. At 7.76% average, you are never truly recovering. Expect long stretches in the 8–10% range broken by brief flatter sections, with the terrain building toward sections that ramp sharply above 15% before hitting that extreme upper ceiling.

The 45.39% maximum gradient represents a very short, very violent pitch. These wall-ramp sections — common in the French pre-Alps and massifs — often appear around tight hairpins or where the road cuts directly up a hillside rather than traversing. When the gradient spikes this aggressively, momentum is your enemy if you arrive in too big a gear, and your only friend if you carry just enough speed to stay upright.

Gradient Behaviour by Phase

• Lower slopes: The climb begins at 649 m. Early kilometres on Category 1 climbs of this profile tend to offer the most manageable gradients — use them to settle into a sustainable power output well below your threshold. See understanding FTP for climbers.
• Mid-section: Average gradient demands suggest the middle kilometres maintain or exceed the 7.76% mean. Do not mistake a brief easing as permission to accelerate.
• Upper section: This is where the maximum 45.39% pitch is most likely to appear. If your legs are already acidic, a ramp of this severity will force a dismount. Arrive here with reserves.

Pacing Notes

A 927 m total ascent over 7.5 km does not allow for a negative split in the way a longer, more variable climb might. Your best approach is to establish a power output you can sustain for the full duration and hold it, accepting that the steep ramps will briefly spike your heart rate and perceived effort.

For a climb of this category and length, a target somewhere in the 85–92% of FTP range is realistic for trained riders. If you do not yet have a current FTP figure, use the FTP estimator to set a working number before attempting a full effort here.

Gearing Recommendations

The 45.39% maximum gradient is the single most important number when selecting a gear setup. On a pitch of that severity, even a compact chainset (50/34) paired with an 11-28 cassette will leave many riders grinding or stopping. Consider:

• Compact chainset with a 32 or 34-tooth cassette as a minimum for riders who intend to ride the entire climb without stopping.
• Sub-compact or 1x setups with a wide-range cassette (40t or larger) give the best insurance against the wall sections.
• Cadence will collapse on the steepest pitches regardless of gearing — the priority is having a gear low enough that you are not forced to stand and rock on a gradient where traction is already marginal.

Summary

The Col du Bez is a serious Category 1 climb that earns its rating through sustained steepness and an extreme maximum gradient. Its 7.5 km length and 927 m of ascent are manageable for well-trained riders, but the 45.39% maximum pitch demands low gearing, disciplined early pacing, and legs that still have something left when the road turns savage. Treat the average gradient as your ceiling early on, not your floor.