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Routes
Mountain biking trails
France
Ile-de-France
Palaiseau
Les Ulis

Vallée de la Mérantaise – Montjay Tunnel loop from Les Ulis

Routes
Mountain biking trails
France
Ile-de-France
Palaiseau
Les Ulis

Vallée de la Mérantaise – Montjay Tunnel loop from Les Ulis

Hard

3.7

(3)

14

riders

Vallée de la Mérantaise – Montjay Tunnel loop from Les Ulis

02:27

29.4km

530m

Mountain biking

Hard mountain bike ride. Good fitness required. Advanced riding skills necessary. Some portions of the route may require you to push your bike. The starting point of the route is accessible with public transport.

Last updated: June 18, 2026

Tips

Includes a segment in which cycling is not permitted

After 18.1 km for 200 m

Waypoints

A

Start point

Bus stop

Get Directions

1

6.08 km

Underpass beneath the N118

Highlight • Bridge

Very narrow pedestrian crossing, but practical for passing under the N118

Translated by Google •

Tip by

2

8.60 km

Technical Forest Singletrack

Highlight • Trail

Small, ultra-technical descent, with steps and rocks.

Translated by Google •

Tip by

3

15.1 km

Vallée de la Mérantaise

Highlight • Gorge

The Mérantaise Valley, near Villiers-le-Bâcle, is a veritable green haven in Île-de-France. The trail runs along the Mérantaise River, winding through dense forests, meadows and wetlands rich in biodiversity. It …

Translated by Google •

Tip by

17.4 km

Viewpoint

Viewpoint

5

23.6 km

Singletrack in the Vallon de la Frileuse

Highlight (Segment) • Trail

Nice piece of forest single track, barely technical except when fording at its end.

Translated by Google •

Tip by

6

27.0 km

MTB Descent

Highlight (Segment) • MTB Park

departure: over the tunnel, clear road

Translated by Google •

Tip by

7

27.7 km

Montjay Tunnel

Highlight • Trail

Like the nearby Fauvettes viaduct, the Montjay tunnel once served as the old Paris-Chartres railway line. In the middle of the communal forest of Bures-sur-Yvette, it punctuates the straight and rolling line leading to the viaduct.

Translated by Google •

Tip by

B

29.4 km

End point

Bus stop

Loading

Way Types & Surfaces

Way Types

9.49 km

8.83 km

5.49 km

2.82 km

1.81 km

526 m

406 m

Surfaces

10.0 km

8.98 km

3.48 km

3.22 km

2.63 km

808 m

234 m

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Elevation

Elevation

Nothing selected – click and drag below to see the stats for a specific part of the route.

Highest point (160 m)

Lowest point (60 m)

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Weather

Powered by Foreca

Wednesday 8 July

33°C

20°C

0 %

Additional weather tips

Max wind speed: 18.0 km/h

to get more detailed weather forecasts along your route

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Our route recommendations are based on thousands of hikes, rides, and runs completed by other people on komoot.

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