A 6km mountain bike loop has been constructed at the Tahune Airwalk, though only half of it is new single trail with the return journey mainly along gravel roads. The outward journey includes some fun riding through nice forest and alongside the river with chances to explore sites less visited by the crowds.
I do note that the official website lists the "Forest Bike Track" as being part of your General Admission to the site, so you may need to pay to access the trail (this wasn't the case last time I was there).
Tahune Airwalk is about 90kms drive south of Hobart. Head there via Huonville and Geeveston where you turn off and head the last 28kms out to the site. It's about a 90 minute drive, and there are good tourist signs showing the way there.
Tahune has a cafe, information centre, toilets etc.
There's only really one way to do this circuit (in a counter clockwise direction).
For those looking for other rides in the area, there is the Tahune Marathon route which provides great riding, and there is the now seldom visited ride and walk out to Reuben Falls a further 13kms or so past the airwalk across the bridge.
Beware of pedestrians on the first section of this route, and if taking young Children be aware of traffic on the road on the way back.
This track is well signed, and so track notes aren't really needed.
From the visitor car park, head around past the registration building and cycle (or push) your bike down the disabled access ramp which leads down to the bridge before the airwalk.
Cross the road and head into the bush directly in front of you (don't cross the river) following the MTB Route signs. The first 1.5kms follows a gravel track which is shared with those doing the two bridges walk, so be aware that you are likely to regularly be passing pedestrians along the way.
About 1.5kms from the car park, the footpath heads off to the right (to cross the river) and there is a metal gate across the track, head past this gate (following the signs). The next 2kms consists of fairly muddy undulating trails which you will probably have all to yourself and this is the best part of the ride from both a riding and scenery viewpoint. Unfortunately it comes to an end all too quickly as you are dropped out onto a gravel road next to a bridge 3.5kms from the start.
It's worth going for a ride over the bridge and back before following the gravel road back towards Tahune Airwalk. A road comes in from your right about 600 metres from the bridge, but continue straight ahead and 5kms from the start you'll drop back down onto the bitumen road which you drove in on on the way to the Airwalk.
Go left at this junction, then almost immediately on joining this road (at the next corner) leave it again on the left and head along a trail which will drop you back out onto the track you followed out. From here retrace your steps back to the Airwalk.