This makes use of the Taff Trail to take you away from Talybont. The Brinore Tramway takes you a short way up into the forest before you descend to the shore of Talybont Reservoir. Crossing over the dam wall you make your way to the other side of the valley and some very hilly riding in Talybont forest and its surroundings. Apart from the climbs, you are rewarded with some fine descents, ranging from fast fire roads to rocky and slippery sunken roads.
More information can be found here: http://www.mtbbreconbeacons.co.uk/english_pages/hubs.htm