Sonic headcanon: There are two types of Extreme Gear: Street Gear (often simply called, “Gear”) and Racing Gear (or, “Racers,” for short).
As their names imply, Street Gear is the kind of Extreme Gear that normal Mobians can buy and use everyday, and Racing Gear is the kind used only by the professionals. As such, special Class 1 Racing Licenses are required to own and operate them.
Racing Gear differs in that, apart from being legally confined only to sanctioned race courses, they are also constrained by its extremely particular Gear-To-Infrastructure communication tech to stay within the physical limits of the track. Street Gear, meanwhile, though technologically inferior and slower than Racing Gear, can be used to travel anywhere.However, practically the moment Extreme Gear became available to the masses, dedicated aftermarket companies began selling upgrades or “Gear Parts” to Street Gear owners, to allow them to modify their Gear to be faster, lighter, more aerodynamic and more advanced than factory-stock Gear.
Some owners even began extensively rebuilding and retooling their own Gear themselves. These owners subsequently held race days specifically for Street Gear riders. At first, no Racing License was needed, but over time, a Class 2 Racing License became a requirement for Street Gear riders, alongside their existing Street License.Because of the wildly popular Street Gear tuner scene, Extreme Gear manufacturers began selling faster Gear and even Gear Parts that could make one’s Gear more akin to the earlier Racers, while simultaneously upgrading their own Racing Gear to be even faster, and using them as test beds for new technologies.
Despite this, the Street Gear tuner scene still flourishes. Team Sonic and the Babylon Rogues are evidence of this, with their specially modified, custom-built Gear.