When you reach the D12, continue along the narrow road opposite. In the hamlet of Coëffrin, go past the large farm typical of Brie and follow the road on your left. Turn right into the track after the water tower, then left to cross Couperdrix and follow the road opposite to the D71. Zigzag to take the track. On the D71E, turn left.
At the fork, bear right back to the starting point.