High above the village of Abergynolwyn, in a side valley where the sheep outnumber everyone, the spoil heaps of Bryneglwys tell you that this quiet corner of southern Snowdonia was once an industrial place. Slate was cut here through the second half of the nineteenth century and into the twentieth, and the whole reason the little Talyllyn Railway exists is to carry it down the valley to the coast at Tywyn. The quarry finally closed just after the Second World War, and the railway, which should have died with it, was taken over by volunteers in 1951 and became the first preserved railway in the world. You can still walk up from the old incline at Nant Gwernol into the quarry workings, past roofless barracks and wheel pits, with streams running through all of it.
The riding around here is gentle in speed and big in scenery. The B4405 from Tywyn follows the Dysynni and then the Fathew valley up to Tal-y-llyn lake, a long ribbon of water under the steep southern face of Cadair Idris. The road is narrow, the stone walls are close and the sheep consider the tarmac theirs, so it rewards a calm pace rather than heroics. Beyond the lake you join the A487 and climb to the junction at Cross Foxes, then drop either to Dolgellau or south towards Machynlleth, and that stretch has real corners and real views. Off the main roads the lanes become single track with passing places and grass up the middle.
Near the mouth of the valley sit the ruins of Castell y Bere, built by Llywelyn the Great in the thirteenth century to guard this approach, and it is worth the short detour for the setting alone, on a rocky knoll with the Dysynni flats below. Further down, Craig yr Aderyn, Bird Rock, is one of the odd places in Britain where cormorants nest inland, a reminder that the sea once reached much further up this valley.
There is nothing at the quarry itself, so think ahead. Tywyn and Machynlleth both have fuel and shops, Barmouth too, and Aberystwyth is the nearest proper town if you need more. Abergynolwyn has a café and a pub, and the station at Tywyn has tea rooms for railway people. Pack waterproofs whatever the forecast says: Cadair Idris makes its own weather, and it usually makes rain.