Assuming you mean Valence in the Drôme (which sits right on the Rhône between Lyon and Avignon — a natural stop on your route), here's what's worth your time.
Valence bills itself as the gateway to the south of France, where the climate and pace start turning Provençal. The old town rewards a slow wander through cobbled streets and shaded squares. The standouts:
Historic center and monuments
- Maison des Têtes ("House of Heads") — a Renaissance mansion from around 1530, covered in carved human and animal heads, now housing a heritage interpretation center with exhibitions and guided tours.
- Cathédrale Saint-Apollinaire — one of the city's oldest monuments, with distinctive polychrome stonework.
- The Pendentif — an unusual sandstone funerary monument in the cathedral cloister, built in 1548 in the shape of a triumphal arch; one of the first monuments ever listed by France's historic-monuments commission.
Parks and riverside
- Parc Jouvet — the city's beloved landscaped park near the Champ de Mars, with lawns, fountains, and the Kiosque Peynet, a pavilion beloved by locals since 1942.
- The ViaRhôna cycle path runs right along the river — given your cycling bent, you could easily do a stretch of it (the section between La Roche-de-Glun and Le Pouzin is a nice one), on foot or by bike, through vineyards and villages.
Food and wine — this is where Valence really earns its reputation.
- The market on Place des Clercs (Thursday and Saturday mornings, 7:30–12:30) is full of Drôme produce: apricots, peaches, walnuts, and the local caillette.
- Maison Pic — Anne-Sophie Pic's three-Michelin-star restaurant, one of France's most celebrated. Worth knowing about even if you don't book; it's a landmark of French gastronomy.
Quick trips nearby
- Tain-l'Hermitage (~20 min north) — famous Rhône vineyards (Hermitage, Crozes-Hermitage) plus the Cité du Chocolat Valrhona.
- Crest (~30 min) — home to one of Europe's tallest medieval keeps, at the entrance to the Drôme pre-Alps.
- Château de Grignan and the International Shoe Museum in Romans are both within reach if you have more time.