About 200 Extinction Rebellion climate change activists gathered in Cardiff on Tuesday to mark the start of three days of action in the capital.
After a gathering in Queen Street, protesters mounted bicycles and cycled slowly in groups along some of the city's main roads at evening rush hour.
The group wants politicians to declare a climate emergency.
It follows Extinction Rebellion's protests in London, which have led to the arrest of about 1,000 people.
Tuesday's protest and group cycle will be followed by similar events on Wednesday and Thursday.
Louise Gray, a 57-year-old maths teacher, said she had helped organise the Cardiff protests for a number of reasons.
"We're trying to work with politicians to make the changes needed in a reasonable time frame to help save our planet," she explained.
"The government now have people power on their back, I think we're going to see real change."
Siôn Elis Williams said he hopes the Cardiff protest can help sustain the national movement and believes disruption is a legitimate tactic.
He added: "To be able to draw attention to a problem that isn't going away requires a totally different approach that needs a really radical solution that isn't in sight at the moment."