Col du Frêne

Overview

Col du Frêne is a Category 1 climb in France, running 10.1 km from a valley start at 390 m to a summit at 1030 m. Over that distance it delivers 640 m of net elevation gain at an average gradient of 6.32%. On paper that reads as a steady, honest climb — long enough to matter, but not a wall.

The paper version is misleading. While the net gain is 640 m, the total ascent over the climb is 902 m. That 262 m difference is real climbing you do and then give back: the road undulates rather than rising cleanly. Every metre of descent inside the climb is a metre you have to re-earn, so the effort is higher than the net numbers suggest, and your rhythm gets broken repeatedly along the way.

How the Gradient Unfolds

The 6.32% average is a blend, not a constant. Because the profile undulates, that figure averages together brief descents, flat drags, and pitches well into the double digits. Riding to the average will leave you either over-cooked on the steep sections or coasting through the flat ones.

• Flatter and false-flat sections that let the average drop — use them to recover, not to attack.
• Short descents and dips where you briefly lose elevation, then have to climb back.
• Repeated punchy ramps that spike well above 6.32%.
• The steepest ramp hits 23.15% — a short, brutal pitch that demands your lowest gear and will punish a rider who arrives already redlined.

Pacing Notes

On an undulating climb like this, chase even effort, not even speed. Holding a constant pace forces huge power spikes on the steep ramps and wasted energy on the flats. Instead, hold a steady sustainable power output: ease slightly on the ramps, and keep pedalling with intent on the flatter sections rather than soft-pedalling.

Know your ceiling before you start. If you haven't tested recently, run the FTP estimator and set a target you can hold across all 10.1 km. Bank effort on the shallow parts; don't spend it there.

Gearing

The 23.15% maximum ramp governs your setup. That gradient is too steep to muscle over on standard road gearing without wrecking your legs. Run a compact (34-tooth) or sub-compact chainset paired with a wide-range cassette — a 34×32 or 34×34 gives you the low gear to spin the steepest pitch instead of grinding it. Check your chainset and cassette before the ride; the ramp is not the place to discover you're one gear short.

Summary

• Length: 10.1 km
• Average gradient: 6.32%
• Maximum gradient: 23.15%
• Net elevation gain: 640 m
• Total ascent: 902 m
• Category: 1

Col du Frêne rewards riders who respect its undulation. Pace to effort, gear for the 23.15% ramp, and treat the 902 m of total ascent — not the 640 m net — as the real cost of the day.