Here is an article which talks about the alternative to the Olympics that takes place in Tehran, Iran. It could change locations like the 'regular' Olympics do, but so far they have not.
It says, "Some events, such as equestrian, were open to male viewers because Iranian equestrians have designed a special horse-jumping chador for their female competitors."
Here is a picture of a lady supposedly wearing one of the special horse-jumping chador. All I see in someone jumping a horse while wearing an oversized long hoodie and a white vest. http://www.iranian.com/PhotoDay/2000/August/horse.html On further reflection, although I did find the other above article in my search results...that might not actually be the chador I wanted to see. *sigh*