A4059 from Penderyn north, joining the A470 up to Brecon.
Not a complex twisty road - its fast, smooth and has good visibility ahead as you go through the mountains and past lakes. On a quiet day, the whole A4059 can be done on the wrong side of the speed limit
Really great road as theres some cracking cambered corners that you can really plant the car into.
Just watch out for sheep
