The nude protesters used paint and stickers to cover their private parts during the eye-popping demonstration in Sao Paulo.
Riders called on the Government to do more to protect cyclists from reckless drivers, after 37 people were killed in road traffic accidents in the city alone in 2017.
Dozens held up signs saying “Your hurry costs a life,” “Vulgar is your lack of respect”, “Obscene Traffic”, and “Out with the Cars”.
Figures show that Sao Paulo ranks as the fourth deadliest city in the world for bike riders, according to international consultancy firm Infix.
Los Angeles, Moscow and New York took the other top spots as the most dangerous places to ride a bike.
In Brazil, thousands of cyclists are killed in road traffic accidents each year.
The Ministry of Health revealed that 8,496 cyclists were killed between 2010 and 2015.
The passionate protesters in Brazil took to the streets with support from the “World Naked Bike Ride.”
The event bills itself as “a protest against car culture and oil dependency.”
Events are held worldwide – in London, South America, and several American cities.