Park at the car park by Llanelltyd bridge and walk up to the ruins of Cymer Abbey. Just before the Abbey, there is a gate on your left which follows the river through a couple of gates and a stile (in the fence on your left after about half a mile).

You can follow it to the end and climb over the stile andĀ up a steep bank to end up on a quiet road which leadsĀ back to Llanelltyd.