About 20 km west of Paris, the state-owned forests of Saint-Germain-en-Laye and Marly form two large neighbouring woodlands, linked by the Plaine de la Jonction. Managed by the ONF (Office national des forêts, the French national forestry office) and served by train, they give Paris-region mountain bikers a vast network of forest tracks, ideal for beginners or for piling up the miles without leaving the Paris area.

Saint-Germain-en-Laye forest

Tucked into a loop of the Seine between Le Pecq and Poissy, the Saint-Germain forest covers 3,532 hectares, all within the municipality of Saint-Germain-en-Laye. It is the third-largest forest in the Île-de-France region, after Fontainebleau and Rambouillet. A former royal forest, it is criss-crossed by long straight rides and star-shaped crossroads, largely closed to cars, under a canopy of oak, beech, hornbeam and sweet chestnut. In its northern half the soils are often sandy.

Marly forest

Between Saint-Germain-en-Laye and Versailles, the Marly forest (around 1,750 hectares, including the Bois de Louveciennes) sits on an elongated hill cut by small valleys, so the terrain is noticeably hillier than at Saint-Germain. Mostly oak and sweet chestnut, it has some fifty ponds. From the Croix Saint-Michel, the view stretches across western Paris.

The waymarked cycle routes

The Saint Germain Boucles de Seine conurbation (the "Agglo", the local group of municipalities) and the ONF have laid out nine waymarked cycle routes, 71 km in all: seven in the Saint-Germain forest and two in the Marly forest. The network combines loops, town-to-town crossings, family circuits, a more sporting route, a section of the Paris–London cycle route and a loop linking three stations (Achères-Ville, Achères-Grand-Cormier and Saint-Germain-en-Laye). Around 300 marker posts and 15 signboards guide riders. The surface remains natural (gravel). Route maps and an interactive map are available on the Agglo's website.

The rules

These busy forests are shared with walkers and horse riders. ONF Île-de-France Ouest applies the following rules:

  • Stay on the roads and tracks provided. Riding inside the forest compartments (off the tracks) is prohibited by the French Forest Code, as is riding on roads closed to public traffic. In peri-urban forests, the ONF restricts bikes to tracks more than 2.50 m wide and to waymarked routes.
  • Follow the signs and the closures of fragile or protected areas.
  • No freeriding and no trails cut off the existing paths: this is prohibited in state forests and can lead to a fine.
  • Walkers have priority. Slow down and get off your bike if needed.
  • Hunting. From September to March, some sectors are hunted. Access is then prohibited and marked by "chasse en cours" (hunt in progress) signs.

Who is it for?

  • Families and beginners: the family loops and the wide rides of the Saint-Germain forest.
  • Cross-country and e-MTB: the sporting route, the station-to-station crossings and the Marly valleys for a little climbing.
  • Enduro and downhill: this is not the terrain for it. Narrow paths off the routes and man-made trails are prohibited.

Practical information

  • By train from Paris: the RER A runs from central Paris to Saint-Germain-en-Laye (the end of the line) in around 30 minutes; Achères-Ville and Achères-Grand-Cormier stations are linked to the forest by a waymarked route. For Marly, take Transilien line L from Paris Saint-Lazare to Saint-Nom-la-Bretèche–Forêt de Marly.
  • From the airport: from Paris-Charles de Gaulle, take the RER B to Châtelet–Les Halles and change there for the RER A to Saint-Germain-en-Laye.
  • Before you go: check the hunting calendar published by the ONF, updated during the season.
  • Forestry work: logging operations can temporarily close tracks. Follow the signs on site.

For other rides and events in the département, see Mountain biking in Yvelines. For a larger, rockier forest, see also our guide to the Forest of Fontainebleau.

Useful links