I have ridden this route twice in 2003 and 2004 thinking it was my own secret! Now the secret is out, go and ride it. It is a mix of very fast, open bends and much tighter and technical bends towards Nyons - take care, a mistake here with the rock walls of the gorge would be nasty. Knocks spots off the old classic and crowded alpine routes.
Because it goes from nowhere important to nowhere important carries little traffic but is superb. Serres end lovely long fast bends and the Nyons end drops through a gorge (beware on blind bends) but the road is wide. Stop for a drink in Rosans or Nyons.
Sisteron has an amazing rock formation overlooking the town, good place to eat and also has tyre fitters who do bike tyres.
D994/94 across from Serres to Nyons beautiful flowing road through a valley, fast open corners, highly recommended. Ideal road to tie in with run up or down the route Napoleon