Planned in the 1960s and built over the following decades, it is a district of roundabouts, cycle paths, office parks and lakes, sitting on the plateau west of the Chevreuse valley, and the people who live here are mostly commuters to Paris and La Défense.
The ride to this point has come out of the Chevreuse valley, so the contrast is sharp. Here the roads are wide, smooth and well signed, which makes them easy but not exciting, and the many roundabouts are best taken with care, especially in wet weather. But a short ride south brings you into old Trappes and the forested side valleys, where the lanes narrow and the villages have kept their stone churches and farms.
The most interesting thing nearby is natural. The Étang de Saint-Quentin, a large artificial lake on the town's edge, is a nature reserve for birds, with reedbeds that attract herons, grebes and, in winter, many wintering ducks. A cycle path runs round the water, and benches along the bank give you a good view. The national velodrome, built for track cycling and used in the 2024 Olympic Games, is also just beside the lake, and visitors can sometimes watch training sessions.
Versailles, with its famous palace and gardens, is only a few kilometres to the north-east, and it is easy to visit if you have time and energy. Fuel and food are no problem: the town has large stations and shopping centres, and many chain cafes and restaurants. A bakery in the old village of Voisins offers a sandwich and a coffee, and the lake is a pleasant place to eat it.
At the end of a dawn loop, this is a quiet and orderly place to finish, with a little nature and a hint of history to round off the morning.