Well I wouldn't agree with the comment that "rider" is someone who always complain. That is simply not true. I take "rider" as a person who has not achieved the full equestrian knowledge I.e. Tacking, saddle, making his room, mucking etc. (Sorry my horse terminology is not that good). Though they can "ride" a horse pretty good.
There are people who employ people to do the mucking, tacking etc, and all they do is ride and they do ride pretty good.
That's just my opinion, I may or may not be wrong here. However I am certainly not wrong to say "riders" are not generally "complaint freaks".
Rooster, alot of men ride horses in Middle East and Asian countries, more women ride in western countries I guess. Though as iridie rightly said, it's just a term and not gender divided.