The Greenbush recreation area has two trail systems: 4 loops of challenging mountain bike trails totaling 9 miles, interwoven with 5 loops of hiking trails totaling 13.5 miles. The Greenbush trails dish out some tough kettle moraine riding. Single-Track. The glaciers that moved through this area left behind deep hollows with steep sides. This trail system provides lots of flow and plenty of rocks. Mountain biking througout the Greenbush trails is a rocky, rollar coaster bike ride, giving you a real workout!