Seen this feature a couple of times in the Tour. The views from the Lacets above Culoz inspired me to ride up on a beautiful September afternoon. Only one car came past in 90 minutes of climbing.
As has been stated up thread, the climb hits you almost immediately on leaving Culoz. My Garmin showed plenty of 14% ramps up to the Lacets at about 7 kms in, which afford spectacular views down the Rhone valley towards Aix les Bains.
After the hairpins, the road cuts through the forest with extended straight sections of up to 17%. The only reason this climb averages about 7% is that there are a couple of kms which afford some recovery.
The last 3 kms take you above the tree line, and if the cloud cover is absent, there are wonderful views towards Mont Blanc.
This is a superb climb. The shade afforded by the forest would be precious protection in hot weather. Blog item