This route is the wonderful Peregrine Path beside the River Wye, with a bit of rural road riding tacked onto the start.
An enjoyable country lane from urban Cwmbran leads to the characterful little town of Usk. Local campaigners have successfully lobbied for a new path to be created along a former railway here, so we’d expect this section to be replaced by a traffic-free path in due course – perhaps including the well-preserved Usk Tunnel! Usk itself has a lovely market square (complete with welcoming pubs) and a privately-owned tumbledown castle.
From Usk through Raglan the road has a bit too much fast traffic for our liking, and we'd suggest peeling off onto quieter lanes. Raglan itself has shops and pubs, though unfortunately the castle is marooned on the far side of the dual carriageway.
Near Dingestow, peace returns as far as Monmouth. The route through the town isn't yet open, intended to go via a corrugated old railway bridge over the Wye which you can walk - safely, but with some difficulty! Backstreets to the main Wye Bridge provide an easier alternative.
From here the popular Peregrine Path (firm, unsurfaced) leads to the charming riverside resort village of Symonds Yat and the Saracens Head pub. If the ferry is running you can cross here for the final leg to Goodrich Castle, or just continue on the same bank following the signs.