Col du Glandon

The Climb at a Glance

The Col du Glandon is a Category 1 climb in the French Alps. Starting at 1,128 m elevation, it rises 1,097 m over just 7.9 km to its summit at 1,886 m. That 9.6% average gradient is not a number to skim past — it means the road is relentlessly steep across its entire length, with almost no flat or false-flat recovery built into the profile.

The 25.5% maximum gradient is an outlier worth planning around. A single ramp at that pitch can shatter a pace that felt comfortable seconds earlier.

How the Gradient Unfolds

With 1,097 m of total ascent compressed into 7.9 km, there is no gradual warm-up phase here. The climb engages hard from the lower slopes and rarely releases pressure.

• Lower third: Expect sustained double-digit gradients early. The road establishes its character immediately — this is not a climb that eases you in.
• Mid-section: The average holds firm across the middle kilometres. Any brief softening in pitch is short-lived and should be used to recover breathing, not to push power.
• Upper third: The steepest ramps, up to 25.5%, appear as the summit approaches. At this point, accumulated fatigue from 5–6 km of hard climbing makes the upper pitches disproportionately punishing. Legs that feel manageable at the base will be under serious stress here.

Pacing Notes

At 9.6% average over 7.9 km, the Col du Glandon sits in a range where most riders will be working at or above their functional threshold power if they're not disciplined about the opening kilometres.

Start conservatively. The gradient is high enough that any early surge will cost double later. Target a power output you can genuinely sustain for the full 7.9 km — not the pace that feels comfortable for the first two.

Treat the 25.5% ramp as a separate problem. When you hit the steepest section, reduce power output slightly and focus on cadence and form. Trying to power through at full effort on a 25% gradient is a reliable way to blow up before the summit.

Settle your cadence early. A higher cadence (80–90 rpm) will protect your legs across the sustained middle section better than grinding a big gear. Use whatever gearing gives you that range without forcing your knees.

Gear Selection

For a climb averaging 9.6% with ramps to 25.5%, compact or sub-compact chainring setups are not a luxury — they're practical. A 32t or 34t rear sprocket paired with a compact crankset gives most riders the low-end range to manage the steepest pitches without losing cadence entirely.

If you're on a standard double, know your lowest gear before you start and make peace with grinding at low cadence on the upper ramps. Pushing through a 25.5% pitch in a gear that's slightly too big will tax your knees and core as much as your legs.

What to Expect Overall

The Col du Glandon earns its Category 1 rating honestly. The combination of a high average gradient and extreme maximum pitch, with very little relief built into the 7.9 km profile, places it among the more demanding Alpine climbs by effort-per-kilometre. The 1,097 m of ascent is substantial for the distance involved.

Estimate your finish time using the FTP estimator before you go — it will help you set a realistic power target and avoid the most common mistake on climbs like this: going out too hard.