All these routes have become a paradise for bikers, thanks to their splendid bends and the beauty of the surrounding countryside.
A highly dangerous construction process!
Tens of years of extreme hardship and dangerous work were necessary: impressive paths cut into the cliff sides, corbels projecting over the void, tunnels piercing the rock, and steep-sided trails at the bottom of the gorges.
Having left Grenoble, a stop at Sassenage is a must. There is the 17th-century castle and listed gardens to visit, as well as Les Cuves de Sassenage grotto, the realm of the Fairy Mélusine. Take the Vercors plateau road through the Furon gorges.
The first step is at Lans en Vercors, a traditionally-built village and headquarters of the Vercors Regional Natural Park.
Go on towards Autrans and Méaudre, famous Nordic ski resorts in the heart of the mountain range, to see numerous farms with slate gables and lanes lined with thackstone.
Then you travel through the Bourne gorges, an iconic way into the Vercors. A succession of tunnels, carved and corbelled, leads to Rencurel, then Choranche. Be sure to visit the Choranche caves.
Next step: Pont en Royans, a very picturesque village where the houses grip the rocks and seem to be hanging over the Bourne.
Get back onto the Vercors plateau via the Petits and Grands Goulets, vertiginous roads carved into the vertical cliff faces.
Once back up there you can visit Villard de Lans, a health resort in a conservation area since the 1920s. Today it is a family holiday resort which offers all manner of activities throughout the year.
Return to Lans en Vercors then St. Nizier du Moucherotte. This is the highest village in north Vercors. A memorial site awarded a Resistance medal, in 1968 it hosted the ski jumping event in the Grenoble Olympic Games (beware: access to ski jump is dangerous).
You come down into Grenoble by the D106, which gives an exceptional panoramic view over the city and its surrounding area.