Beneath the vineyards of Épernay lie roughly 110 kilometres of chalk galleries, cut into Belemnite limestone laid down when the Paris Basin was a warm sea. Those tunnels hold millions of bottles at a constant 10–12°C. The town above calls itself the capital of Champagne, and the claim is arithmetical rather than romantic. The Avenue de Champagne runs barely a kilometre, yet the cellars below it store more wine by value than any comparable street in France. UNESCO inscribed the Champagne hillsides, houses and cellars as World Heritage in 2015, naming the Coteaux, Maisons et Caves as a single cultural landscape. An epernay champagne bike tour reads that landscape from the outside in — riding the ridges that the galleries only imply. The route from Le Clos Corbier, 51160 Mareuil-sur-Ay, France sits at the hinge between two terroirs: the Montagne de Reims to the north, planted overwhelmingly to Pinot Noir, and the Côte des Blancs to the south, where Chardonnay dominates the chalk. Mareuil-sur-Aÿ itself is a Premier Cru village on the left bank of the Marne, a short ride from Aÿ, classified Grand Cru. The distinction is not decorative. It reflects a nineteenth-century pricing ladder, the échelle des crus, that graded villages by percentage and shaped who grew what. Riders on an Epernay champagne vineyard tour pass parcels still worked by hand because the slopes exceed the gradient a tractor can hold. Vollereaux, Aÿ, Cramant, Avize: the names on a cellar door correspond to soil, aspect and altitude before they correspond to a label. What makes the region legible by bicycle is scale. Villages sit three to five kilometres apart, linked by service tracks between rows. Electric assistance flattens the chalk climbs that once made the Côte des Blancs a walking landscape, which is why epernay champagne bike tour tours now reach cellars that coach itineraries skip. Riesling-thin soils, riddling racks, remuage, dosage, the second fermentation in bottle — the technical vocabulary of méthode traditionnelle is easier to absorb standing in a gallery than reading it later. Phylloxera reached the Marne in 1890 and the vineyards were replanted on American rootstock over three decades. Grower Champagne, bottled by the family that farms the fruit, has expanded since. The address at Mareuil-sur-Aÿ keeps free entry at 0 EUR; the excursions themselves are priced independently. Hours run 09:00–17:30 Wednesday through Sunday, with the site closed Monday and Tuesday. A morning arrival keeps riders inside the same rhythm the harvest has kept for four centuries.