It starts inside the town and goes up at an easy 7% Markers show each of the 20km you are about to climb.
You get flat bits at 1,100m right through St Alban des Villards then pay for it with 10% chunks immediately after. Then the full high pass opens out, you can see where you have to go which is daunting.
Once on top you can see the Croix der Fer 2.5km further on. Riding to it is much easier with 5% max and spectacular views.
Cafe notes - Glandon has a bar 200m off the top. Croix de Fer has one right at the top.
Special mention to Christope who rode some of the way with me.