I've swum in the rivers round there (mostly in pools below the waterfalls), but haven't actually cycled in that area. When I lived just inside the Brecon Beacons national park I was only cycling a few times a year, and rarely more than 10 miles at a time.
By the time I got back into cycling (early in the Pandemic), we had moved down to Abercynon, and then down to the Vale of Glamorgan.
There were a few times, when we had visitors, we would take two cars, park one in Penderyn, the other in Port Yr Ogof car park, then walk the river path between them, past the waterfalls.