Stunning: there's no other word for it. This rail trail up the Afan valley, smoothly surfaced and traffic-free, could be the finest of the Valleys' many cycle routes.
The Afan valley is particularly narrow and undeveloped, with an almost Swiss character in places. The gradient is gentle, the sort that you don't notice on the way up but enjoy on the way down.
It's 11 miles from Port Talbot to the head of the valley at Glyncorrwg, from where you can choose to climb for another two miles on a forestry track to meet NCN 47 down to Neath. But we'd suggest returning the same way you came, perhaps stopping for lunch at the Cymer Refreshment Rooms in the old railway station.