Vermuntbahn parking lot. Take it to the top station and from there by bus to Bielerhöhe.
From the Bielerhöhe you descend shortly down to the lake and then put the skins on. Usually the lake is frozen over in winter and even partly groomed, so that it can be crossed in a straight line. At the end of the lake (Klostertal) you keep to the valley on the right and ascend through gently rising terrain to below the Klostertaler Umwelthütte.
You now follow the Klostertal further uphill, always keeping to the left (east) of the stream. Via a wide left turn you reach the Klostertal Glacier and follow it up to the Rotfluh gap. Usually, there is already a good track here.
There are now two options for climbing up to the Schneeglocke. The GPS track covers both. In my case, we have made a depot under the ridge boom and continued by foot. Under safe conditions, you can also climb the steep snowfield (35-40°) towards Piz Grambola with the board. Below the summit or over the crest you can cross to the wide ridge towards the Schneeglocke.
Alternatively there was a footpath up the steep slope (40-45°) directly to the ridge, which we followed in the ascent. From the ridge simply continue to the top of the Schneeglocke.
Descent like ascent.
Option 1: At about 2950m you can traverse to the right (NW) and descend via different steep couloirs. It's best to keep to the north.
Option 2: Follow the same route as the ascent, but keep right at about 2700m to the rock face. You now reach a beautiful couloir, through which you reach the valley floor.