The inland braid of the Celtic Trail is an uncompromising ride through South Wales, a fabulous - if sometimes tough - route taking in everything from mining railways to the remote Preseli Hills.
Start at Newport and head up the unexpectedly scenic old Crumlin Arm canal to Risca, a real "little Switzerland". Railway paths take you from valley to valley, the mining settlements hidden by fierce woodland.
Then after Abercynon the wilderness begins, a gravel ride before gravel was trendy. 25 miles of forestry tracks will challenge your stamina, but those with a yen for the off-road will need no convincing. The surface becomes beautiful tarmac at Neath, following the old canal towpath down to Briton Ferry, where you rejoin the main NCN 4 through Swansea.
After Llanelli, an exceptional rail-trail - almost Swiss in its lush, hillside scenery - leads on to Carmarthen and the remote lanes over the Preseli Hills (source of Stonehenge) to Fishguard and the Cardigan Bay.
This is not one for the beginner or the skinny-tyred road cyclist, but a route full of character.