Col de Porte

(S/E) At the start of the Col, take the D57D which continues as the D57E where it is closed to cars when covered with snow.
Pass the Centre d'Etude de la Neige on the right and go down to a junction
(1) with a forest path that you take on the left and which runs through the forest. Signpost in the direction of "La Pinéa"

Travel about 500m and turn left onto the trail(2) that snakes up to spot height 1491, ignoring all the paths going off to the right. You then move along a ledge (3).

Climb slightly up to spot height 1544 and pass the sloping trail that switches to the left. Continue along the ridge line and then after going through an open section with no trees, fork right (4) on a steep climb.

At the top of the climb (5), turn right and follow the Tour de Chartreuse GRP. This takes you directly north up to the summit of Mont Fromage (1662m) where the view now looks out west(6).

Continue along the ridge on the Balme de l'Air until altitude 1703 (7) then down to the intersection with the D57E where you'll find the Orgeval oratory (8).

Take the road to the right, going south and follow it until your reach the Col de Porte(S/E).

Be careful, cross-country skiers do not necessarily use the same itinerary and leave tracks in the snow that do not follow the same route as hiking trails, which can be misleading.
Use good snowshoes with poles.

Superb views:
(3) South over Grenoble and the Vercors in the distance.
(6) Over the entire Chartreuse mountain range and beyond.