Instructions
Start the "Mario Kart Wii" game and point your Wii remote at the "Start" option. Press the "A" button to enter the main menu.
Select your file and then select the "Single Player" option. Select the "Grand Prix" option by pressing the "A" button.
Select the "100cc" option and then select the character you want to play as. Use the Wii remote to select the bike you want to race with.
Use your Wii remote to select the "Automatic" or "Manual" option, and then select the first set of Grand Prix Cup races.
Complete each race in every Grand Prix Cup by finishing in first or second place, and you will receive a one star rating or higher. The game will then automatically save, and you will receive a message that says you have unlocked the Sneakster bike.