Hi guys I found a rainbow road skip method. While the Jackal Leader is giving you the final speech, keep pressing Tab to drain your health. Pressing it about 8-10 times will drain it enough. After the speech, u get to the rainbow road. You will see that your health is 10-20. Now, jump from the edge of the road and make your character die from the fall. That’s it. The “You Win” card will pop up. You just fooled the game that u completed rainbow road. this will be good strat to chop off a few minutes from your run.

Note: Doesn't work on Campaign+, you have to actually win the race there.

i learned the hard way one has to finish RR for full credit, i.e. the biker achievements.