Sierra was a national women’s motocross racer when she sustained a T6 spinal cord injury. At the age of 16, she was competing one last time in the men’s division at a local race before heading to her first national race season in 2013. Halfway through the race, she hit a pothole before a jump, her suspension kicking her over the handlebars. She bent “like a taco”, snapping her spine and pinching her spinal cord.