The Col du Glandon, between Savoie and Isère, owes part of its reputation to its immediate neighbour, the Col de la Croix de Fer, with which it shares most of its route: the two summits are climbed almost as one continuous ascent.
The profile from Allemont
From Allemont, expect about 26.6 km and 1,379 m of climbing, averaging a moderate 5.2% that masks steeper sections interspersed with flatter stretches. The road first skirts the Barrage du Verney dam before climbing in switchbacks through Le Rivier-d’Allemond, the last village before the final push into alpine pasture.
Getting the ride right
The length of the climb matters more than its moderate average gradient: it’s better to pace the effort over the full distance rather than aiming for a high tempo from the bottom. Riders in good form can carry on for an extra 2.5 km up to the Col de la Croix de Fer to double up.
When to go
June to September, as snow can linger late at this altitude early in the season. July-August remains the busiest period, particularly during Tour de France passages.
Good to know
Allemont, at the foot of the climb, offers a convenient starting point with direct access to Le Bourg-d’Oisans for combining the ride with other Oisans giants such as Alpe d’Huez or the Col de la Croix de Fer.
