This is a nice almost fully circular route starting by parking on a street just next to a bridleway that takes you up onto the common. The high point is not the trig point, but the grassy mound nearby. This route takes in the trig point and the true high point.
Foel Trawsnant is only 371m high, but this route has a decent amount of ascent although it is largely gentle. Views are quite broad and the open land is nicely grassed with decent tracks and paths throughout.
The bridleway is signposted from the main road, so head up the lane and through some semi-abandoned farm buildings, the gate is unlocked, and follow the path around and up.
Eventually you get to the end of the fences and you can take a left up a track and follow that around until you pick up a public footpath that then crosses with St Illtyd’s Walk, but you go over the stile and head straight to the trig point. Once at the trig point you can see that the true highpoint is not much further on.
You can head to that and then stroll through golden grass down to pick up another decent track that you can follow until you pick up the bridleway again, taking a right turn and follow it back to where you started. A nice walk and a decent hill with good views.