I rode a route planned on Cycletravel. Route 322053.
On day two at 49-50 km between Pant y Colli and Penrheol (you can see these on OS maps) the route choose a path that went through two farm yards with closed gates and the path was made of fist sized rocks that I couldn't ride up or down.
The road surface seems to be correctly labelled on Open Streetmap