If racing cross country through tight bush trails and fast open tracks appeals to you, then you should consider enduro riding. It's a case of rider and bike versus the elements in events ranging from casual trail rides to Australian Championship events. For many enduro events a standard requirement is a registered, adequately silenced motorcycle. A civil license or permit is required in some states.

Age Limits
starting age , upper age limit

Facility Availability 
Tracks, clubs etc

variety of classes
for all levels of ability

Cost
Entries, bikes, protective gear, memberships etc

The initial cost can be moderate to expensive if you buy all new gear. But there are many bargains. protective clothing can often be found at less then 1/2 price at many swap meets. Membership fees vary from club to club as does competition entry fees. but you will need to obtain a license from the governing state body an affiliate of the controlling body Motorcycling Australia