When it happens, it happens so fast that you can't even react in time to do anything about it.
Most people just hang on for dear life and hope for the best.
Even professional motorcycle racers fly through the air with the greatest of ease and pray they don't hit anything. They are taught to get away from the bike and spread their arms and legs out to slow them down. But that's on racetrack without any vehicles coming their way or trees to hit or telephone poles to stop their flight. They trust their fellow racers to react to precarious situations and void running over them. Motorcycle racers have the experience to do what they can to avoid that well-known Sudden Stop.