Northwest of Brisbane near Chapel Hill in the Brisbane Forest Park, the south and east sides of Mt. Cootha have several very popular, but steep, trails. A good trailhead is Slaughter Falls on the south side or Gap Creek Reserve on the west side.
Make sure to check with local land managers as to the status of this land for mountain biking prior to heading out.
Overall, Mount Coot-tha is the 1st most popular mountain bike trail of all 30 mountain biking rides in Australia.