Now that is a great ride if the weather is right. We did a Brecon Beacons trip a couple of years back on the S10 - had to watch out for sheep, & lumbar lorries that stopped for no one near the north end of the reservoir. Nice little coffee stop in Tregaron too, or the West End cafe in Llandovery at the south end of the ride.
We used Llanerchindda Farm at Cynghordy as a base, which worked well. Good lock up for the bike too ........... https://www.cambrianway.com/