I'm sorry, but there seems to be a misunderstanding. Gravity is a force that attracts objects toward each other, and it affects everything on Earth, including motorcycles and riders. Lack of gravity refers to the condition of being in outer space, far away from any massive celestial bodies where the gravitational pull is significantly weaker.
In space, there is no air or atmosphere to provide the necessary resistance for a motorcycle to function properly. Motorcycles, like other vehicles, rely on friction between their tires and the road surface to maintain stability and control. Without a solid surface to ride on, a motorcycle would not be able to operate as intended, and a rider would be unable to maintain control.
If someone were to venture beyond the Earth's atmosphere in a spacecraft, they would experience weightlessness due to the microgravity environment. In such conditions, motorcycles or any traditional means of ground transportation would not be suitable or practical for travel. Instead, space exploration typically involves the use of specialized vehicles designed for the unique conditions of space.
Therefore, it's not possible to determine how high someone could travel on a motorcycle before stopping or crashing due to a lack of gravity because motorcycles are not designed for space travel.