Class Flash ActionScript

package{
  import flash.display.Sprite;
  
  public class Main extends Sprite{
    public function Main(){
        var eighteenSpeed:Bicycle = new Bicycle(18);
        var fixedGear:Bicycle = new Bicycle(1);
        
        trace(eighteenSpeed.gears); //18
        trace(fixedGear.gears); //1
    }
  }
}
    class Bicycle
    {
        private var _gears:Number;
        public function get gears():Number
        {
            return _gears;
        }
    public function Bicycle(numberOfGears:Number)
    {
            this._gears = numberOfGears;
        }
    }