The Grande Sure circular loop starting from Curière

From Saint-Laurent-du-Pont, take the road to Saint-Pierre-de-Chartreuse and, 500m after leaving the village, turn right onto the small road to the Col de la Charmette as far as the Chartreuse de Curière. Drive past the buildings and park in the car park before the barrier blocking the road.

(S/E) Leave the Nonne forest road (return route) on your right and take the road to Col de la Charrette. After the barrier, turn right to take the signposted path heading south into the forest. It winds its way up until it reaches very steep slopes, which it helps you to climb, runs alongside rocks and, via a final slope crossing to the left, reaches a shoulder beneath the Rochers de la Petite Vache and the Agneaux: the Pas des Agneaux, with a viewpoint over the Guiers Mort valley to the left.

(1) The Pas allows you to switch to the south-eastern slope, which is steep at first but which the path allows you to traverse whilst remaining more or less level. You thus reach the bottom of the valley to cross the Torrent des Agneaux and turn left to rejoin the Chemin forestier de la Petite Vache, at the "Salle à Manger".

(2) Turn right to head up this wide forest track, which first crosses the stream again before climbing in stages and a few bends along its left bank. Ignore the logging tracks branching off to the right or left. After a climb that brings you closer to the Col des Charmilles along the valley axis, you’ll reach the junction with a path marked ‘Pas de la Biche peinte’.

(3) Take this path which heads off to the left on level ground. It involves a few ascents and descents, particularly to cross branches of the stream, remains generally level at the start and heads south to pass beneath the Petite Vache. It begins to climb gradually up slopes that are half wooded and half scree. The path is sometimes lost following storms or fallen trees, but the marked trail is fairly easy to find again to continue to the foot of a gully which it climbs, first in switchbacks then more directly up the slope, until it emerges onto the ridge: this is the rugged Pas de la Biche.

(4) At the exit of the Pas, turn left to follow a path that runs along the edge of the cliff towards the south-east, then makes a wide descending curve through the forest to cross over towards the south-west. The route flattens out then climbs slightly to join the main path coming from the Col de la Charmette. Take this path on the right to climb in a few minutes to the Col de la Petite Vache.
Please note: the path linking the Pas de la Biche to the Col de la Petite Vache trail is poorly marked but follows sporadic signposting, so it is advisable to keep a close eye out for these markers in the forest.

(5) At the pass, you emerge onto the mountain pastures of the Vallon de la Sure. Turn left to descend slightly into the valley, then follow the correct path passing beneath the Col de la Grande Vache and rising gently to the clearly visible Col de la Sure.

(6) Turn right to climb the grassy ridge, then take the path veering left to traverse the slope across rockier terrain to a sort of small pass. Cross a dip in the terrain to resume the climb towards the summit in sight. Continue to reach the summit of the Grande Sure.

(7) Descend via the same route (or an equivalent path, as there are several parallel routes) to the Col de la Sure.

(6) Return to the valley, staying fairly high on the right bank until just below the Col de la Petite Vache. Then leave the route taken on the ascent and continue descending gently along the hillside towards the north to reach the pass of the Col des Charmilles.

(8) Ignore the path on the right that crosses the pass and the one on the left that descends into the valley towards Cul de Lampe; instead, take the path straight ahead that heads for the wooded ridge of Les Charmilles. After crossing the last field of the mountain pasture, the path climbs through the forest to the ridge. It is poorly marked in places, but the climb to the ridge remains easy. Follow the highest point of the ridge and continue past it until you reach the point where the path turns onto the western face.

(9) Descend this path (sometimes called the Sentier de la Terrasse), which winds its way down the very steep western slope in tight hairpin bends: take great care not to lose the path in this difficult wooded section. You quickly lose altitude, then the slope finally levels out and joins a forest track that follows a gently sloping ridge north-eastwards. It passes the Borne du Sapin des Termes, inscribed in Latin.

(10) Continue straight on along the track, which descends steadily. Further on, it is joined by the path coming from Cul de Lampe and reaches the junction with a stony forest road, the Route de Nonne. Follow it in the same direction until you reach a cross on the left, a viewpoint over the Saint-Laurent-du-Pont valley.

(11) The road continues in the same direction towards another viewpoint, where it turns right into the Curière valley. Follow the road as it descends steadily through the forest and joins the Route de la Charmette at the car park where you started (S/E).

The entire route normally follows paths or tracks, most of which are signposted (though markings are sometimes sparse). In a few sections, however (the Pas de la Biche and Crête des Charmilles sections), the old path has become more difficult to follow, especially where storms have eroded the slopes or caused trees to fall.

In case of difficulty (e.g. high humidity), the route can be simplified:
- by avoiding the climb to Pas de la Biche: continue from (3) towards Col des Charmilles, then ascend the Sure valley from lower down
- by avoiding the descent from the Crête des Charmilles: descend (along the path) to the bottom of the valley to pass the Cul de Lampe and return towards Nonne.

Two-thirds of the route is through varied woodland, whilst the upper section takes place in open mountain pastures.
There are several vantage points along the ridgelines; otherwise, the view from the summit is 360° and stretches as far as the foothills of the Massif Central.