Forest walk leading to the Goulet de Heurtieres, then to the Grande Sure, which offers spectacular views across the Chartruse, to the north and on a clear day Monc Blanc

The guide starts at the Col de la Charmette. The was apparently closed for works, so we parked 3-4km further down, and walked up climbing an extra 300-400m. The actual route in the guide is probably around 12-13km with 900m ascent.

The Guide Franck takes you away from the recommended route, which is marked with yellow markings until ~6km where you leave the PR and take a non marked route. Although there are no yellow markings, there are occasional wooden panels to lead the way, and when not covered in leaves the path is obvious. The reasoning for this rather than the recommended route is that the Col de la Charmette is a large wood depot in the chartreuse and the recommended itinerary is a heavily used logging route. Hence this is very muddy when it is wet. The ascent via  Goulet d’Heurtieres is much more pleasant.

The Guide Franck returns you via the same route as you climbed, but we opted to return via the signed route to make this into a loop. When dry the logging route is actually perfectly fine, but probably best avoided after heavy rain.