The highest point (Foel Cwmcerwyn) is at the west end, just above Rosebush.
I’ve ridden the hills in a variety of ways over the years.
If you start at Rosebush then you have a bit of a slog, either through the (mostly felled) forest tracks or up the bridleway and cheeky path to the very top.
From there you’ve got big downs and steep, short ups all along to the east until you run out of bridleway near Crymych.
Turning round and riding back off road would be fairly shite, I’ve usually slogged back along the road to Rosebush. The bonus of finishing there is Tafarn Sinc and it’s lovely beer.
You could park at the east end and either road to Rosebush or off road it all the way before turning round. But you don’t end at the pub!
Or be really lazy and do a shuttle with 2 cars to avoid the slog.
It will be very, VERY wet up there. Whole wheel swallowing bogs in places.
It’s not the greatest ride in the UK but you won’t see many people and the views on a clear day are amazing. Gower, western Beacons, N Wales mountains and Ireland!
Enjoy!