Flywheel

Flywheels are floating gimmicks featured at early games in the Sonic the Hedgehog series. Flywheels are seen rotating in the mid-air and can be found for most of time from Factory-themed Zones. When the playable character jumps on these wheels, the player can move him around the Flywheel normally without falling to the ground, unless the player jumps off. The player is also able to build momentum, which can make the playable character able to reach higher sections in stages after jumping off at high speed.

Flywheels first appeared in the original Sonic the Hedgehog and have then made few appearances in early games.

Sonic the Hedgehog (1991)
Flywheels can be found for the first time in the original 16-bit version of Sonic the Hedgehog, where they can only be found at large halls of Scrap Brain Zone Act 2. These grey wheels have belts around them, which move clockwise faster than the wheels themselves. When Sonic jumps on the Flywheel, the player can make him walk around the wheel to the belt's moving direction.

If the player makes Sonic perform his Spin Attack, he/she is able to build momentum around the Flywheel. After gaining enough of speed, the player can then do Spin Jump in the right time and make Sonic reach to the higher pathways in the Zone. Depending when the player jumps off the Flywheel, the player either flies to the lateral direction in high speed or down to the bottom ground.

Sonic the Hedgehog 2 (8-bit)
In the 8-bit version of Sonic the Hedgehog 2, Flywheels are featured as major gimmicks in Gimmick Mt. Zone, where they are illustrated as grey and metallic wheels. When Sonic jumps on the Flywheel, he turns automatically into Spin Attack mode. The player is able control the wheel by pressing right on D-pad to rotate faster or left to make the wheel rotate slower. The player can then make Sonic jump off in the right time to make Sonic fly to straight up.

Later in Crystal Egg Zone Act 2, there are smaller, bubble-looking wheels with blue, five-pointed star in the middle. These smaller wheels float to left and right above threatening spike pits. When the player jumps into them, they function identically like ones in Gimmick Mt. Zone, but they still keep moving left and right in the mid-air.

Sonic the Hedgehog CD
In Sonic the Hedgehog CD, Flywheels are only featured at the second Zone of Metallic Madness. Here, their color scheme changes depending the timeline. They function the same like in Scrap Brain Zone, but when Sonic starts perform his Spin Attack on the wheel, the camera direction moves to the right side. Flywheels can be useful for gaining momentum to create time warp in the Zone.