Note: This is not a marked or often walked trail. The trail has plenty of trail markers and as you are walking along the top of a gently sloping ridge you essentially can't go off trail. But it is definitely something for more experienced and prepared hikers. The scramble to the top is also not that hard or that high, but once again, you should know what you are getting yourself into.It is a good idea to take topographic maps with you. You can download these for free from the QTopo website.
The start of the trail is off the Warrie Circuit. Start by following the Warrie Circuit in a counterclockwise manner from the Tallanbana Picnic Area. The start of the Pinnacle Trail is not marked, but it is at the sharp corner of the big switch back in the Warrie Circuit.
Following the trail from there isn't that hard, but you will have to scramble over fallen logs and pass through some scrubby country. Having said that, it is one of the nicest open forest areas I have ever walked through in South East Queensland. If you stop seeing trail markers, just back track until you find them again. We did actually encounter someone who had managed to lose the trail in pretty much the only place where there are not enough trail markers.
The Pinnacle itself is at the end of the trail after about 2 to 3 km of walking and you can't miss it. If you don't feel like doing the scramble to the top you still have great views of the area from the ridge.
The scramble up is not particularly hard or steep, but it is fairly sandy with plenty of loose rocks. So take it carefully and test hand and foot holds. It is a good idea to keep a good spacing between people to avoid dislodged stones landing on anyone's head.
The top only holds a few people, so it is more of a place to get to, look around and then come back down. But well worth the effort to make it there.
Returning to the Warrie Circuit you can either return back the way you came or complete the circuit. As you are nearly halfway along the circuit you might as well keep going. Overall with this diversion it will be around 21 kms to complete the circuit and less if you backtrack.
When getting to the lookouts along the cliffs at the end of the circuit you can see the Pinnacle sticking out like a pile of rocks in the middle of Sringbrook National Park. From a distance it looks much smaller than when you do the climb, but it is also obviously the best place for views in the area.