Belo Horizonte Critical Mass bike rides start from Praça da Estação (Central Station Square) 19:00 hs on the last Friday of each month, and they are free and fun. All you have to do is show up with your bike. See more in Facebook.
Neighborhood Critical Mass rides take place throughout the month, including the group named RUTs (Rolê Urbano das Terças) and start form Praça da Liberadade (every tuesday 19:00 hs). See more in Facebook.
About the city:
Belo Horizonte (Portuguese pronunciation: [ˌbɛloɾiˈzõtʃi]; Beautiful Horizon) is the sixth largest city in Brazil, the thirteenth largest city in South America and the sixteenth largest city in the Americas. The metropolis is anchor to the Belo Horizonte metropolitan area, ranked as the third most populous metropolitan area in Brazil. See more in Wikipedia