here there is a lovely bike trail on the Left, following an old rail line along the mountain. At the cross roads, if you bear left there is a short dead end track that leads you to the Aberdare entrance of the rail tunnel (worth taking a look just to see the stone work!). Go back to the Junction and bear right to continue along the old railway tracks until it turns into a foot path and comes out on a tarmac road . Turn right down this road until you come to Cwmbach, Left at the T junction for 50 yards, then second Left up Cefn Pennar Road leading back up hill, Follow this about half a mile to a large house at the top of the road, then take the path on the Left up hill to the gate at the top, Follow this path Right around the mast on the top of the hill (at Ffynon Y Gog) and keep going past Cefn Pennar farm until you meet the road coming up from Cefn Pennar. Turn Left up this hill, and where the road ends continue along the stony track until you come to a gate leading into the forestry.