Col d'Ugeon

Overview

The Col d'Ugeon is not a climb you ease into. Over 15.5 km it averages a brutal 10.85%, dragging you from a start elevation of 381 m all the way to a summit at 2058 m. That is 1677 m of net elevation gain, with 1661 m of total ascent packed into a road that almost never lets up. There is a reason it carries the HC label — hors catégorie, the "beyond category" rating reserved for the hardest climbs. At these numbers, the Col d'Ugeon sits firmly among the most punishing paved ascents you can point a bike at.

How the Gradient Unfolds

An average of 10.85% is already ferocious, but averages hide the real story. On a climb this steep, the gentle stretches are few and the ramps are relentless. The gradient peaks at 25.71% — a wall steep enough that traction, balance, and sheer leg strength all become limiting factors, not just aerobic fitness. Because the average sits so close to eleven percent across the full 15.5 km, there is little in the way of recovery. Where gentler climbs give you flatter shelves to spin and breathe, the Col d'Ugeon keeps the pressure on from the 381 m base to the 2058 m top. Expect the steepest sections to arrive without warning, and plan to have something in reserve for them.

Pacing Notes

On a climb averaging 10.85% for 15.5 km, pacing discipline is everything. Ride the lower slopes at or just below your FTP and you will still have matches to burn when the road tilts toward 25.71%. Go over threshold early and the sheer duration — you are climbing 1677 m — will find you out long before the summit. A good rule of thumb is to treat the first third as controlled, the middle as steady, and hold enough back that the steepest ramps do not force you off the bike.

If you are unsure of your threshold, use the FTP estimator to set realistic power targets before you commit to the lower ramps. Knowing your number turns a survival grind into a paced effort.

Gearing

Do not under-gear this one. With a 10.85% average and pitches to 25.71%, most riders will want the widest range they can fit. A 34×32 is the practical minimum for staying seated and spinning on the steady sections, but on a climb that hits 25.71%, a 34×34 gives you the extra rescue gear that keeps your cadence alive when the road stands up. If your frame and derailleur will accept even more range, take it — over 1677 m of climbing, protecting your knees and your cadence pays off long before the top.

Summary

The Col d'Ugeon is a genuine HC test: 15.5 km, an average of 10.85%, and ramps to 25.71% that demand both fitness and gearing. Pace it honestly, gear it generously, and respect the 1677 m of vertical between the 381 m base and the 2058 m summit.

Length: 15.5 km
Average gradient: 10.85%
Max gradient: 25.71%
Start: 381 m
Summit: 2058 m
Net gain: 1677 m
Total ascent: 1661 m
Category: HC