Passo Gardena is located in the Sella group of the Dolomite's and is one of the 4 Passes riding in the Marathon di Dolomiti each year and one of the most recommended rides to do for its beauty. You normally would not want to ascend or descent from the St. Christina area due to the traffic. That road is the tour bus road to bring everyone up to see the Dolomiti.
There are three roads to ride to Passo Gardena
From Chiusa: Try to time yourself to be riding during low traffic.
From Ponte Gardena