The Min River comes down out of the Tibetan edge of Sichuan in a hurry, and the Chengdu plain below it would have flooded every year if a governor named Li Bing had not worked out how to tame it in the third century BC. His Dujiangyan scheme, begun around 256 BC, splits the river with a man-made island and a cut through the hillside, sending the surplus to the sea and the rest into canals that water the plain. It still works, more than two thousand years later, which is the real wonder of it, and it is the reason Sichuan became known as the land of abundance.
You walk out over suspension bridges and look down on the water as it boils and divides. The sound of the river is a constant, and the sight of anglers and old men on the quay gives the place an everyday feel that is easy to forget amid the tourist crowds. Mount Qingcheng, a few kilometres away, is a different thing, a wooded hill covered in Daoist temples, traditionally the birthplace of the Daoist religion in its organised form, with stone steps, tea houses and bamboo thickets.
Riding up from Chengdu you travel a fast, well-surfaced road across the plain, often busy with trucks, and then the country starts to lift. The road to the Wolong panda reserve, which this stop shares a ride with, climbs along the river into forested mountains, and it is still marked by the effects of the 2008 earthquake, with rebuilt bridges and tunnels and fresh retaining walls. Corners are more frequent as you climb, and rain, mist and rockfall are all real possibilities, so check conditions before you go.
Fill the tank down on the plain, because the towns up in the valleys are smaller and services thinner. Tianpeng, the nearest sizeable place, has what you need. Local food is Sichuan food at its best: hotpot, mapo tofu, and the tea of the Qingcheng hills, served in the old tea houses where nobody will hurry you.
Spring and autumn are the best times, because summers are hot and humid and winters are damp and grey. Tickets and entrance are in the usual Chinese pattern, with a lot of walking involved, so wear shoes rather than riding boots if you can.