Koblenz is a small Swiss town on the Rhine, and its job on this ride is simple: it is where you cross back. Across the river lies Waldshut, the German side, and the pair are connected by an old bridge that has seen centuries of toll collectors and, later, customs officers. Today the border is open and relaxed, but the habit remains of stopping here to sort out the practical things before the road home.
The setting is flatter and gentler than the Black Forest you have just left. The Rhine here is wide and green and moves with a quiet weight, and not far upstream the Aare joins it, bringing the waters of half of central Switzerland to the party; the rivers meet near Koblenz in a confluence that does not look like much from the road but is among the most important in the country. Downstream, the Klingnau reservoir is an internationally recognised bird reserve, where herons, ducks and, in winter, huge flocks of migrants gather on the shallows.
For riders the point is fuel. Waldshut-Tiengen, a town of twenty thousand, has everything, and Klingnau, a few minutes down the valley, has a pretty little old town with a medieval look. Switzerland requires a vignette to use its motorways, so if you plan to take the fast road home rather than the lanes, check that you have one.
The roads around Koblenz are mostly practical rather than thrilling: river roads, commuter lanes, the occasional slow farm vehicle. But the evening light on the Rhine can be lovely, and in the late afternoon the quiet water and the old bridge make a good pause before the final run home. Keep your passport or ID with you, because spot checks still happen.