sentence: The video begins with the annual BMX biking event where several participants are gathered to begin their competitive event. sentence:  Several bikers begin biking on their bikes on curved slopes in the open air arena. sentence:  The bikers go over bumpy and hilly slopes in their gears and helmets. sentence:  There are several bikers beginning a race from the top of the biking slope. sentence:  They show off their stunts and skills as they speed through the obstacle course of the biking arena.