Simone Biles and Riley Gaines exchanged a series of tense comments online over disagreements on transgender athletes. Here's everything to know about Simone Biles and Riley Gaines' feud.

Gaines' extensive history of attacking transgender (and cisgender) women in sports led Biles to call her a "bully" in an X post.

Olympic gymnast Simone Biles apologized to anti-transgender activist Riley Gaines this week, after a brief but fiery feud that included Biles apparently endorsing “fair” restrictions on trans athletes in sports.