One of only two Duocons, the other being Battletrap. They are unique in that their robot modes are formed from the combination of two separate vehicles. In Flywheels case his alternate modes are a tank and a fighter jet. Flywheel's two halves hate each other and are contstantly arguing even when they are united to form the robot mode.
 
The Duocons were Shockwave's attempts at creating a Transformer with more than one alternate mode. He failed since Flywheels' consciousness was split between both vehicles. Shockwave finally succeeded in his attempts when he created the Triple-Changers.
 
He was killed by Galvatron as the Mayhem Attack Squad confronted him and Megatron during the Time Wars.