The final step is to mount the cage. All that is needed are a pair of 12 inch bungee cords. I do like to fold a towel and place it between the platform and the cage. This helps to absorb the viration from your biking surface. (You should very much avoid biking on rough surfaces with your bird, but some small bumps are always going to be part of the environment.
Fold the towel so that it is as wide and long as the cage. You should have about 6 layers of towel at least when you get done. Place the cage on top of the towel and platform and hook each bungee cord to the bottom side rungs of the cage on one side, run under the platform to the other side, and then hook to the other side as shown.
Add a perch as shown to allow your bird to perch comfortably, add a toy or two and something to chew on and you are all set. At the time of this writing Barney and I have biked over 3000 miles and the cage is none the worse for wear.