I have moved away from the area so wouldn’t know the exact current local trail situation but…
… climbing either from around Wyllie partly on road or up 2 mile climb off road on to the Sirhowy Valley side of things gives lots on nice steep singletrack/ rocky descents back down in to Crosskeys.
Or, you could take some of the rocky descents in to Bedwas/ Trethomas which then open up tons of stuff south of Caerphilly/ Ridegeway/ Wenault/ Whips/ Castle Coch/ singletrack of Machen etc etc etc.
A lot of those are marked bridleways so it is not really giving away any secret local knowledge and not too hard to find with the option of disappearing down some unmarked singletrack for even more fun.
There must be tons North and East of Cwm Carn too towards Mr. Loco so it is just a case of getting in touch with a LBS and getting a map or GPS or joining one of their group rides. There aren’t many boggy farm tracks round those parts!