From Grenoble, take the tram A to Terminus "Fontaine la Poyat" From the Terminus, there are 2 solutions:
By bus: take a bus in the direction of Sassenage Line 19 or 20 or 50 and stop at "Sassenage Castle" or "Ovalie. More info here: Plan-Metropole-Grenoble-2018-10 A 5-minute walk to the Sassenage Church from the bus stop. Attention - less frequency during the weekend / holidays. Plan-Metropole-grenobloise-2018-10
On foot: A 22-minute walk from the Terminus to the car park of Sassenage Church. More info here: Walk from la Poyat to the parking of lower part Furon : Itinerary on foot to get to the canyon from Grenoble