Extreme Gear

Extreme Gear (or X-Gear, or just plain Gear) are the various air-powered hoverboards, skates, and bikes/scooters/etc. of the Sonic world (first introduced in Sonic Riders).

The science

This is mostly unspecified in the games. After a little discussion about it, it seems that the most logical conclusion is that we simply don't bother explaining what makes them function, but instead how they actually function in this RP. So here's a few quick, point-by-point, unorganized blurbs describing their basic properties.

Ground effect is necessary for flight

The strongest output of air comes from the bottom of the gear, and much like a hovercraft, the gear is kept aloft by thrusting against the ground, allowing it to ride on a high-pressure cushion of air. This means that when the gear ramps, it cannot truly fly. It will simply soar through the air like a plank, losing forward momentum and falling as gravity dictates until it's again right above the ground (i.e. in "ground effect"), where it can again form a cushion of air to ride on. (Flight type gears are an obvious exception, as they apparently have higher power thrusters that can optionally be activated for full-fledged short-distance flight, though that should logically use more air in this RP, since we're not restricting the flight to big, silly aerial booster rings.)

Gears recover air while not in ground effect

To adapt the "trick" method of recovering air into something that makes sense for RP, we've assumed that whenever a gear ramps into flight, its main jets stop running, allowing the compressor to recover air. For the sake of convenience, we can also assume that gears recover air when not in use (such as when being carried).

The thruster on the back is mostly only for boosting

The thruster on the back of most board/bike gears is barely running most of the time, so twisting around or flipping in the air will not slow the boarder down much. It only really pushes hard when boosting.

Rings play no part in the gears' performance

This is a gameplay element we can't really play into an RP since we don't have chains of rings all over the place. It'd be kind of hokey.

Zero Gravity gears

No information yet.

Performance

The average Gear isn't that fast; action in Sonic Riders was pretty slow. You're probably looking at cruising speeds of anywhere between 140-180km/h (87-112MPH), which is pretty pathetic in light of real-world cars, motorcycles, etc. Their main advantage is their ability to navigate all kinds of different surfaces and terrain, including water. Still, we took the liberty of bumping the unspecified units in Sonic Riders from the implied km/h to MPH so that the average cruising speed for an XG in this RP is in the 140-180MPH neighborhood, sometimes higher. Feel free to get pretty speedy with X-Gear. Just don't get outrageous.