There is only one rule: get out there and ride.
Here at RideApart, with lady writers and editors, the day to celebrate woman riders is any day ending in "Y." That's no reason why ladies around the world shouldn't saddle up and celebrate it as an official event, however. While May 4 is most widely known among fans and punsters as Star Wars Day (May the 4th be with you), for 2019 it doubles as International Female Ride Day. Don't worry, a Princess or General Leia costume is not required.
According to the Motoress website, IFRD is "a campaign for women motorcycle riders across all cultures of the sport, with the purpose of highlighting and profiling the many numbers of woman riders enjoying the activity." The way to participate is simple: be a woman, and ride a motorcycle that day. That's it. All makes and models are welcome, including scooters. You don't even need to own a motorcycle yourself.
There are ways to get more involved, of course. There are organized events all over the world where women who don't want to participate alone can meet up and ride together. Share photos of yourself and your bike to social media using the hashtag #IFRD. You can even take it a step further and enter the official IFRD photo contest, where a jury will vote on three finalists and a winner decided by Vicki Gray, who founded IFRD back in 2006.
While we consider women to be equal to men when it comes to riding a motorcycle, we also recognize that women are still a minority in the sport, though continually growing in numbers. It's also true that some people, including many women, don't feel comfortable riding alone, so there is some value in having an organized event such as IFRD to encourage these people to hit the road. No matter what gender you identify, more riders on the road is a good thing.