Harris was a professional motorcycle road racer — the first African-American woman to compete and be licensed n the sport. She died after she appeared to lose control of her bike, which then crashed through the window of a building during filming of the 20th Century Fox superhero movie.
She was reportedly not wearing a helmet because the film character she was doubling, Domino, played by Zazie Beetz, was not supposed to be wearing a helmet in the scene. British Columbia workplace accident investigators would not confirm whether she was wearing a helmet.
"Deadpool 2" was Harris' first role as a stunt performer in a film, according to Deadline Hollywood.
Not wearing a helmet went against a stringent pro-safety biking philosophy Harris promoted on her personal blog.
"My gear costs what I thought my body parts were worth. Basically, it was an investment," she wrote.
"INVEST whether you want to just hit the track one time or become a track junkie or a racer, INVEST IN YOUR BODY."
She reportedly had completed the stunt successfully several times before the crash occurred. A witness said the bike seemed to accelerate when it should have slowed down as she took a corner.
Harris began riding in 2009 and received her race license in May 2013, CBC television reported. She started competing in 2014, racing in the American Sportbike Racing Association's Championship Cup Series.
A 2015 article in "Black Girls Ride" magazine described Harris as "the first African American female road racer." Harris told the magazine, "I am everything people never saw in this sport."
Porsche Taylor, editor of the magazine, wrote on Facebook of her friend's death: "SJ was a real life superhero, and not just playing one on film."
In her blog, Harris wrote of the danger, "It crosses mу mind at times, but a racer can't let it stop us. Weren't we all scared of crossing the street before we understood what made us scared?"
"I've learned to accept that I am not the greatest rider that exists and that there is alwaуs something to learn when on track and pushing limits. Sometimes I'm going to eat it if I'm impatient. Everуthing takes time. Face уour fears уou never know what [уou're] missing out on."
"Deadpool 2" star Ryan Reynolds said actors and crew were "heartbroken, shocked and devastated" at Harris' death.
The movie is a sequel to the 2016 R-rated superhero comedy from 20th Century Fox.
The B.C. coroner and workplace safety officials are investigating. It's the first death of a stunt actor in the province's thriving movie industry since 1996.
Material from Reuters was used in this report.