jefmcg
Guru
And it's the only sport I can think of where the sex of the rider (and the horse) is irrelevant.
There's another one: shooting. And that's when it gets interesting ....
Shooting used to be open in the olympics, so men and women competed against each other. In 1976 a woman got a silver. It was only a matter of time before a woman beat all the men and got a gold. Obviously such a disaster must be avoided! By 1984, they split shooting into separate men's and women's competitions.