Cracklister.com

Go to the Game Mode screen and enter
•    Right, Up, B, B, A, B, Up, B, B, A.

UNLOCKABLES ACHIEVEMENTS

Extreme Bike Collector (50) - Purchase all extreme bikes
50 Races (50) - Play 50 races, online or offline
Accredited (100) - All rider credits awarded
Challenge Expert (30) - 50 challenges completed
-    Challenge Master (60) - All challenges completed

-    Extreme 1000 - Legend (60) - Win a career mode extreme 1000 season on Legend difficulty
-    Extreme 1200 - Champion (50) - Win a career mode extreme 1200 season on Champion difficulty
-    Extreme 1200 - Legend (75) - Win a career mode extreme 1200 season on Legend difficulty
-    Extreme 1200 - Professional (25) - Win a career mode extreme 1200 season on Pro difficulty
-    Extreme 600 - Legend (30) - Win a career mode extreme 600 season on Legend difficulty
-    Extreme Mode Champion (10) - Win any extreme mode championship at any difficulty
-    Finish 250 Races (30) - Finish 250 races, online or offline
-    Finish 500 Races (50) - Finish 500 races, online or offline
-    GP Champion (60) - Win career mode grand prix season on Champion difficulty
-    GP Legend (100) - Win a career mode
grand prix season on Legend difficulty
-    GP Professional (30) - Win a career
mode grand prix season on Pro difficulty
-    GP Rookie (10) - Win a career mode grand prix season on Rookie difficulty
-    Seeded #1 (75) - Seed #1 achieved
-    Seeded #10 (50) - Seed #10 achieved
-    Seeded #25 (30) - Seed #25 achieved

- Seeded #50 (20) - Seed #50 achieved - Seeded #75 (15) - Seed #75 achieved
-    Seeded #90 (10) - Seed #90 achieved
-    Stunt Mode Rider (10) - Win a Stunt Mode game in any multiplayer mode