From Mario Kart Racing Wiki
Toadette on her Jet Bubble A.K.A. Bubble Bike
The
Jet Bubble, or Bubble Bike in the Japanese and European releases, is Small size
bikein Mario Kart Wii. An average bike, the bike is good for beginners. It can be unlocked by winning the
Leaf Cup on
Mirror Mode. The heaviest of the light bikes, the Jet Bubble has average stats. Its strong points are speed and drift, although these aren't very high. Its
off-road attribute is low, and the other stats are in the middle.