National Cycle Network Route 4 (part) covers 196 km across three stages, starting at Mathern and finishing at Idole in south Wales. The route progresses generally westward, passing through places such as Caerphilly and Swansea along the way.
The first stage from Mathern to Caerphilly is 63.8 km with 317 m of climbing. It features two climbs: an early 3 km climb gaining 74 m with an average gradient of 2.4%, and a later 2 km climb gaining 66 m at 3.4% average. This stage passes through many towns including Chepstow, Newport, and Caerphilly.
Stage two covering 75 km between Caerphilly and Swansea involves more climbing with 534 m elevation gain. It includes four climbs, notably a 3.2 km ascent gaining 180 m averaging 5.7% with a maximum of 10.8%, and another near 2 km climb gaining 99 m at 5.3% average. The highest point reached in the tour is 237 m here. The route passes through towns such as Pontypridd, Port Talbot and ends in Swansea.
The final stage, Swansea to Idole, is 57.3 km with 245 m climbing, featuring a single climb of 3.6 km with 122 m gain at 3.4% average. The route goes through Llanelli and Pembrey among other places, concluding at Ferryside near Idole. Water or food stops number 38 on the first two stages but fewer on the third with 27.
No temperature or seasonal data is provided. The climbing is moderate overall with the middle stage having the most sustained and steepest ascents. The route remains within Great Britain throughout.
