In the vault final, gymnasts vault twice and the scores are averaged.
Biles scored 15.900 on her first -- an Amanar -- with a short hop back.
She spoke briefly with her personal coach, Aimee Boorman, between vaults and came back with an even better showing on her second one, the Cheng, and scored 16.033.
The silver went to Maria Paseka of Russia (15.253) and the bronze to Giulia Steingruber of Switzerland (15.216).
Of note, a 41-year-old took part in the vault final, Oksana Chusovitina of Uzbekistan, who was competing in her seventh Olympics.