There's a few up in Trevallyn. A trail sort of has a few on it.. Best way to find it is start at the top carpark at the Gorge, then just walk up the trail. There's a firetrail to the right of it. Follow that to the powerlines, walk left for like 300ms, then the trail is on the left. It's probably the best set of jumps in Launceston.. apart from private ones.