The Frontend is the Main Menu of Re-Volt. The frontend can be made driveable in by renaming everything to some other level and fooling the game into thinking it is a track.
Although when playing this track, there is no collision on anything except for the floor. Also another noticeable problem with this track is that the car boxes' textures are garbled. They represent textures like the road signs. One last thing is you start in an odd position. You start on top of almost every one of your opponents. Some of the cars also start in place of the clockwork table.
Custom Frontends are also possible by replacing the world (.w) file in the frontend folder e.g. Sakura Frontend.