The 12-km section linking Lamastre and Les Nonières follows the River Sumène as far as Saint-Prix, where it crosses the village and continues a few kilometres towards the Medieval village of Désaignes (classified a "village de caractère").
Along this section of the cycle path, the technical expertise involved in building the former rail track in particulary evident. Look out for some impressive retaining walls, bridges, viaducts and tunnels - the tunnel at Les Nonières in the longest one found along La Dolce Via, continuing for 320 metres ... with lighting ! The viaduct at Saint-Prix consists of five 12-metre arches plus a smaller arch that crosses above the road. Lamastre, a town well-known in the world of cinema, as several films, or parts of them at least, have been shot here (Les Cracks, The Judge and the Assassin, La Colline aux Mille Enfants, and The Children of the Marshland), it is also the terminus of the Mastrou, the legendary steam train. There’s no better way to explore the Doux Gorges.