"I feel empowered and happy. We confirmed today that our society isn't backwards," said 25-year-old Marina Jaber, who cycled with her long brown hair down and an Iraqi flag draped around her neck to applause from bystanders.
Iraq does not ban women from cycling, but female cyclists are rarely seen because of a conservative society that frowns on them doing so.
"We cycled through the streets and drank juice," said the artist and graduate in nutrition studies. "And the only comments we overheard were: 'Iraq is doing just fine'."
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For several weeks, images of Jaber cycling around Baghdad have created a buzz on social media, and her Instagram account has more than 29,000 followers.
In one photograph, Jaber overtakes an old man straddling a bicycle who appears to glare at her, while a young boy nearby grins as she passes.
Another young woman, who joined Monday's bike ride and gave her name only as Mina, said she had joined in the hope of changing mentalities.
"When I was little I had a bike and would always ride it. But when I reached fourth grade, my family started fighting me and hiding my bike. They wouldn't allow me to ride it. I didn't understand why," the 25-year-old student said.
"Then it hit me. It's because I am a girl."