First you must unlock Career+ mode by amassing 250,000 rep score. There are four worlds you must complete in succession without losing all your lives: Desert, Jungle, Favela, and Glacier. Each contains a boss track you must complete, although like the Highlands and Forest track in the normal Career mode, you don't have to actually complete all the boss jumps.General tips:
-Take it slow! Focus on conserving your lives.
-Complete bonus objectives that are easy to complete, and don't attempt difficult ones if you think you may crash trying to complete it (for example, "Finish within __ seconds" and "Finish without letting go of the acceleration")
-Choose a direct path to each boss track, but pick easy difficulty tracks and avoid fire nodes and danger zones.Desert Boss:
The pyramid is rather easy to jump over, but you can simply ride around the obstacle and cross the finish line with ease.Jungle Boss:
Although it may be quite a detour, it is possible to navigate off the track and all the way around to the back side of the level behind the jump and slowly pedal your way up to the finish line. Just steer clear of trees as many of them have invisible boundaries that will make you wreck if you get too close. You may also just choose to complete the jump by hitting the ramp at about 80 kmph if your feeling confident.Favela Boss:
This jump is also not necessary to complete. Simply navigate around the buildings and past the statue to the finish line. To complete the jump it is advised to have the crew member to reduce speed wobbles as you will need to reach 90 to 100 kmph to land it.Glacier Boss:
This is the only boss track in Career+ that essentially requires you to complete the boss jump. Watch your speedometer as you make sure to keep your bike aimed at the ramp. Depending on variation between generated levels, you will need to hit the ramp at 95 to 100 kmph. Too slow and you won't clear the gap, and too fast could make you land too hard and wreck. It's intimidating, but not too bad.
Here's a video of how to complete the Glacier boss jump (begins at 2:32 in the video)