Check the gender of the person riding it.
The only gender-specific item you'll find on a bike is the very rare men's or women's -specific seat, designed to protect the reproductive organs, but even those are mostly interchangeable because those vulnerable organs are in the same place on both men and women. The bicycles I build and use have "cruiser-style" seats and promote an erect posture, so the weight is safely on the butt bones.
The confusion is about the two most common frame shapes: step-through and diamond. Step-through frames were built to allow both men and women to commute to work without spoiling their dress pants, skirts or dresses. The design also makes the bike easier to get on and off, and to offers some flexibility in the frame for a bit of natural suspension. It's a city commuting design. Diamond-shaped frames are less flexible, so they're faster on smooth roads, and more durable on offroad terrain. With a bit of suspension, step-through frames offer better speed on urban terrain. Each frame shape has the same effect on male and female users, so everybody should have one of each. They're for different purposes, not different bodies.
Men and women have the same physical needs when cycling. All the little details that have been masculinized or feminized are based on stereotypes that fit one's intentions for a specific trip much better than one's gender. So everyone should have a "man's" bike and a "women's" bike, if they want to talk about it that way.
So what most people think is a ladies bike is actually a formal-wear friendly city bike, and what people think of as a man's bike is actually a sports/highway bike. It's just that people don't think of bikes as highway vehicles anymore, and every product we use has had gender assigned to it as a marketing gimmick.
So that's the full explanation of why I've been "cross-cycling" for years. Not everything is a french noun. Bikes are genderless.