You can park on the grassy verge at SH920075. It is hard going over rough moorland from the path at SH920078 to the forest road at SH925093, but once there you can follow this to near the summit trig point. It is easier but longer to take the right hand track at Clegyrnant to the same forest road (you can cut the corner easily from SH929071 to SH932072), the route by which I returned. This forest road will be bikeable from its northern end on the A458 at SH954127 or its southern end from the minor road at SH951046.
(2 hours, 5.8 miles, 900’ of ascent)