The start and end of this route are only 10 km apart, but it takes you 55 km to do it.
Fill up in St. Jean if you're getting low. The road climbs through trees high on the right side of a narrow (basalt?) gorge, through three (or so) unlit tunnels - two of which have bends in them, eventually opening out onto a high glaciated valley where there are a few ski resorts and fab scenery. The road surface used to be excellent all the way, probably because of the resorts in winter, but has deteriorated in recent years and can only be described as average now [2002]. From the ski resort of St.Sorlin d'Arves, there's a final steepish knee-down climb up through high moorland to the Col de la Croix de Fer [2062m]. A short drop to the 'saddle' where the road to the Col de Glandon turns off right. The surface is average, on the whole.