Take the bus to Woden. Ride to the peak of Isaac Ridge ride and back. First a gentle climb along a good bike path to the southern end of the ridge before doubling back for the second half of the climb and the ascent to the ridge along The Spine singletrack. The ridge is then mostly flat until just before the peak.
Descend from the peak to the bike path and back to the bus. The descent is steep but is a good road. If you do not like steep, turn around at the peak and ride back to the bus station the way you came up.