Protesters gathered in Frankfurt on Saturday to demonstrate for more climate-friendly mobility on the first day that the International Motor Show (IAA) was opened to the public.
Organisers said 25,000 people had come to attend a demonstration outside the event venue in the afternoon, of which 18,000 had arrived on bikes from around the region.
Authorities closed parts of the A661 and A648 motorways to let the swarm of cyclists pass.
Environmentalists have joined together under the hashtag #aussteigen (opt-out) in reference to their call for Germany to opt-out of combustion engines and transition to e-mobility and other climate-neutral forms of transportation such as cycling and public transport.
On the programme for the demonstration, there was a map of bike routes, along which cyclists could join up together on their way to the protest.
The bike protesters began in several big cities around the region, including Giessen, Aschaffenburg, Darmstadt, Mannheim, Mainz and Wiesbaden.
Manufacturers unveil new models at the IAA motor show, which was opened by German Chancellor Angela Merkel on Thursday.
During her visit, she praised the auto industry for stepping up its efforts in developing climate-neutral technologies.
But environmentalists have slammed carmakers for starting e-mobility transition efforts too late and for shirking their responsibility for air pollution, especially in regard to the diesel emissions scandal.
