Complete certain challenges to unlock following riders.

Rider	How to unlock
Alex Barros	Complete Challenge 44.
Alex Criville	Complete Challenge 57.
Carlos Checa	Complete Challenge 54.
Chris Walker	Complete Challenge 47.
Freddie Spencer	Complete Challenge 66.
Garry Mccoy	Complete Challenge 71.
Haruchika Aoki	Complete Challenge 45.
Jason Vincent	Complete Challenge 55.
Jose Luis Cardoso	Complete Challenge 56.
Jurgen Vd Goorbergh	Complete Challenge 50.
Kenny Roberts	Complete Challenge 68.
Kenny Roberts Jr	Complete Challenge 63.
Kevin Schwantz	Complete Challenge 62.
Leon Haslam	Complete Challenge 51.
Loris Capirossi	Complete Challenge 46.
Max Biaggi	Complete Challenge 70.
Mick Doohan	Complete Challenge 65.
Nobuatsu Aoki	Complete Challenge 61.
Norick Abe	Complete Challenge 49.
Noriyuki Haga	Complete Challenge 60.
Olivier Jacque	Complete Challenge 53.
Sete Gibernau	Complete Challenge 48.
Shinya Nakano	Complete Challenge 59.
Takuma Aoki	Complete Challenge 52.
Tohru Ukawa	Complete Challenge 58.
Valentino Rossi	Complete Challenge 69.
Wayne Rainey	Complete Challenge 64.