Hundreds of bike riders shed their clothing and rode through the capital of Spain Saturday protesting the overuse of automobiles, and celebrating the simplicity of bicycles and the human body.

According to the World Naked Bike Ride Website, the annual ride is held in cities all over the world "to celebrate cycling and the human body. The ride demonstrates the vulnerability of cyclists on the road and is a protest against oil dependency."

The event is meant to be a peaceful and humorous. It has a "bare as you dare" policy, meaning it's okay to wear some clothing. Promoters urge riders to wear as little possible and still be comfortable.

The event started in 2004 and encourages people in cities everywhere to organize groups to ride in protests.