Women can generally race in men's races if the so chose.
The only real exception would be men's pro only races. Some of the women on the team I race for here in FL often will enter men's criterium races to get an extra hard workout in addition to their own women's race. I think only a couple of the other women racers in the huge pack had any idea what the hell I was doing. The men seemed clueless. Women can generally race in men's races if the so chose.