Hundreds of riders pedalled across Europe in recent weeks, converging in Portugal, where a group boarded a boat bound for Brazil.
Their destination: Belem, the Amazonian city hosting the UN COP30 climate talks in November.
The summit is expected to draw tens of thousands of negotiators, scientists and activists, with governments under pressure to agree on stronger measures to protect the Amazon and phase out fossil fuels.
The COP30 Bike Ride began in Azerbaijan, host of last year's COP29 summit, and has travelled nearly 8000km across Eurasia in 20 weeks.
More than 600 cyclists have taken part in different stretches of the journey.
A second branch of the initiative covered an additional 1800km across northern Europe with another 200 riders, and others cycled across parts of eastern and southern Africa.
"The main message we want to bring to world leaders and ordinary people is that cycling should be considered a serious option to reduce transport-related carbon emissions," said Dutch organiser Jolein Schorel.
"It's also healthier, cheaper, fun — and one of the most feasible options to implement if cities invest in infrastructure."
Schorel said the project grew from a symbolic ride to COP29 in Baku, where cyclists handed over a banner to a Brazilian delegate promising to reach COP30 the same way.
The journey has struck a chord in communities they've passed through.
In Zambia, schoolchildren listened wide-eyed as riders described crossing thousands of kilometres by bike.
Speaking to The Associated Press on Tuesday, Schorel recounted what she had heard in a morning call from Enock Kitheka, one of the cyclists leading the ride across Africa.
"One boy had only a coin, and he said: 'I don't have much, but I want to support your ride. Maybe it's just enough for some water.' That was so touching," she said.
For Schorel, the ride has been deeply personal.
"To me, it's really special that so many people around the world cooperate to make it happen," she said.
"People join by bicycle, arrange accommodations, contact municipalities. And all coordinate this amongst each other. This makes the ride both internationally and locally very connected. And when we arrive in a town, we are often welcomed very warmly."
After weeks of cycling across Eurasia, they are sailing to Brazil instead of taking a plane, underscoring their pledge to avoid fossil-fuel transport.
Organisers say their approach aims to reach "the heart, the mind and the hands" — the heart through stories of the communities they meet, the mind through practical policy proposals, and the hands by completing the journey without burning fossil fuels.
When they arrive in Belem, riders from the different branches will regroup and cycle into the Amazon's gateway city together.
They plan to present their demands to negotiators as COP30 opens.
"We may be a small group, but our voices — and our pedals — show that we can still choose a different path," Schorel said.
11°C