Accomplish the indicated achievement to get the corresponding number of 
Gamerscore points:

  Accredited (100 points): All rider credits awarded. 
  Challenge Expert (30 points): 50 Challenges completed. 
  Challenge Master (60 points): All Challenges completed. 
  Extreme Bike Collector (50 points): Buy all extreme bikes. 
  Extreme Mode Champion (10 points): Win any Extreme mode championship. 
  Extreme 1000 - Legend (60 points): Win a Career mode Extreme 1000 season on 
  the Legend difficulty setting. 
  Extreme 1200 - Champion (50 points): Win a Career mode Extreme 1200 season on 
  the Champion difficulty setting. 
  Extreme 1200 - Legend (75 points): Win a Career mode Extreme 1200 season on 
  the Legend difficulty setting. 
  Extreme 1200 - Professional (25 points): Win a Career mode Extreme 1200 season 
  on the Pro difficulty setting. 
  Extreme 600 - Legend (30 points): Win a Career mode Extreme 600 season on the 
  Legend difficulty setting. 
  GP: Champion (60 points): Win a Career mode Grand Prix season on the Champion 
  difficulty setting. 
  GP: Legend (100 points): Win a Career mode Grand Prix season on the Legend 
  difficulty setting. 
  GP: Professional (30 points): Win a Career mode Grand Prix season on the Pro 
  difficulty setting. 
  GP: Rookie (10 points): Win a Career mode Grand Prix season on the Rookie 
  difficulty setting. 
  Seeded #1 (75 points): Seed #1 reached. 
  Seeded #10 (50 points): Seed #10 reached. 
  Seeded #25 (30 points): Seed #25 reached. 
  Seeded #50 (20 points): Seed #50 reached. 
  Seeded #75 (15 points): Seed #75 reached. 
  Seeded #90 (10 points): Seed #90 reached. 
  Stunt Mode Rider (10 points): Play a Stunt mode game in Multiplayer mode. 
  Finish 50 races (20 points): Finish 50 races (Xbox Live or offline). 
  Finish 100 races (30 points): Finish 100 races (Xbox Live or offline). 
  Finish 250 races (30 points): Finish 250 races (Xbox Live or offline). 
  Finish 500 races (50 points): Finish 500 races (Xbox Live or offline).