To unlock bike 7 you must beat track Some Hollow in under 38 seconds using rockets. ![][1] To complete this achievement follow these steps: 1. Tap Career from the main menu 2. Tap Time Attack 3. Tap on the Expert Career pack 4. Tap on Some Hollow 5. Complete the race in under 38 seconds and use at least 1 ...
If you do not see the rocket button during a race is most likely because you have rockets disabled in the settings. Go to the settings menu and make sure rockets are turned on. Rockets can only be used in Career mode. If you are playing Jam or Versus mode you will not see rockets. If neither of those help then ...