About 30 Dunedin cyclists pedalled for about 2km along George St, from the Museum Reserve to the Octagon, last night.
They added their presence and their bicycles to an international cycle action phenomenon.
"Critical mass" rides have taken place since 1992 in more than 300 cities around the world.
Held at 5.30pm on the last Friday of each month, they are designed to draw attention to the need for motorists to share the road.
Adrienne Mulqueen, of the cycle advocacy group Spokes, said the rides were called critical mass rides because the more cyclists there were on the road, the more motorists were inclined to take notice of them.
"The one thing which improves safety for cyclists is the number of cyclists on the road. When there is enough of them, they are a force to be recognised."
Participant Anna Star said rides had been held in Dunedin most months for at least six years.
Last night's ride was the largest since last summer.
