This big loop is popular among local cyclists. You leave Oisans by Col d'Ornon to drop down to Valbonnais, then to the plateau of Matheysin. You will climb up to La Morte by a pretty route with little traffic.
Itinerary no. 11 of the “Cycling in Oisans” guide (Oisans Tourisme)
Departure / Arrival (loop): Bourg d’Oisans 720 m
Time: 5 h 30
Distance: 100 km
Highest point: 1380 m
Lowest point: 360 m
Total ascent: 2010 m
Max. gradient: 10%
Map: Michelin Local Map no. 333 Isère, Savoie
From Bourg d’Oisans, follow the D1091 towards Grenoble.
After the second kilometre turn left and follow the D526 towards Valbonnais - La Mure - Ornon. From the pass, go down to Valbonnais.
From Valbonnais, turn right and follow the D26 towards La Mure.
In Sievoz, turn right and cycle on the D114a towards La Morte (ski resort of Alpe du Grand Serre).
Then go to Séchilienne (be careful on the downhill slope) and turn right on the D1091 to come back to Bourg d’Oisans.
ALTERNATIVE ROUTE Via Laffrey
From Siévoz, ride to La Mure on the D26.
After La Mure, take the D115c. Cross through St Honoré, Fugières, Villard Saint Christophe and Cholonge before to go down to Laffrey.
After Laffrey, turn right on the D113 towards Saint Barthélémy de Séchilienne. Then go to Séchilienne (be careful on the downhill slope) and turn right on the D1091 to come back to Bourg d’Oisans.
Distance: 97 km
Time: 5 h
Total ascent: 1836 m