@gadgetrider The Onewheel's design is very different than a hoverboard. On a hoverboard, your weight is directly on the pivot point, so it's easier for the motor to balance you. This isn't to say it's a better design, but this difference is what makes the Onewheel so much more fun to ride and also allows for more extreme maneuvers.
But that benefit comes at a cost: You have to be more careful to keep your weight equally distributed across either side of the wheel or you can nosedive in an instant.
Say you're riding along at around 17mph, if you suddenly shift your weight forward over the front footpad (and off the back one), the motor has no way physically to propel you forward, and it would stop and the nose of the board will dig into the ground as you continue your journey forward (Newton's Laws of Motion can be a bitch).
This all happens in a fraction of a second, so at what point in time would an alarm be anything other than an annoyance? Most of the time, you wouldn't hear it until you were airborne.