A loop you can start from several places. It's the #5 loop in the Layon Espace VTT. It's rated as difficult but is pretty easy. Mud might be the most substantial obstacle. It's well marked and best taken in counter clockwise direction as suggested in guides. The loop can be expanded by joining other courses. I would recommend take loop#4 to make a longer day out. See http://www.layon.org/medias/document/22.pdf
It takes riders through some great vineyards.