The signs on the road for bicycle tourism do not follow the former rail way between Feuillade (Charente) and Saint-Pardoux-la-Rivière (Dordogne). Instead of the road D75 following the river Bandiat, the official way needs a very good physical condition. You will go up, sometimes down and again up a lot of surprisingly steep hills and you will not see the shops and bars where to stop for a drink in Javerlhac and Nontron!
Locals always take the D 75 with their bicycle. The website of Flow Velo (if you want to contact them) here.
Here is a screenshot of the road. Blue F... Vélo between Feuillade and Saint-Martial-de-Valette, red the usual easyer road.