A great mountain bike tour focusing on downhill trails on downhill bikes (I was on a Scott Ransom): By S-Bahn to Oberdöbling, from there to the entrance to the Vienna Woods, up to the Sauberg. Down the Sauberg Trail and on to the trail center in Weidlingbach. There, two climbs and a variety of trails with lots of berms and jumps. Then through the Dombachgraben up to the Sophienalpe and down the Hinterholz Trail to Mauerbachstraße. From there, back via Purkersdorf.
35 km, 4 hrs on the way, around 1000 m elevation