Ojek

Ojek “motorcycle taxis” began appearing in Jakarta after becak were banned in 1994. Ojek service began as a people's initiative to provide a transportation options for people who used to use becak from main roads into housing complexes.
By law all motorcycle passengers should wear helmets, so ojek drivers should have a spare for you to wear. Ojek tend to congregate at t-junctions on main roads and near smaller roads that are not serviced by bus routes. Ladies have a careful balancing act if wearing a dress and must sit sidewise on the back of the vehicle.
Bargain before you get on - ask a local what the price should be first.