I suspect that many of those stares would be there for male bikers as well. The stares are often stares at bikers, not at female bikers. I would also question if a lady biker has to be vain in order to enjoy attention. Some women accuse other women of vanity because of their own lack of self esteem, or because of jealousy. Just feel good about yourself.
I have female friends who assure me that there are just as many women willing to take advantage of them as there are men willing to take advantage. Also, remember that many of those men looking at you may be checking to be sure that you are safe, wondering if they might be needed to protect you or be your knight in shining armor. Of course, some men are capable of being bad guys.
It is probably a good idea for female bikers to try and always be part of a group, preferably three or more. And do not make the mistake of thinking that all bikers can be trustsed.