if going by bus, the air conditioned buses 761d, 751d, 741d, and 7400 make stops along zona sul, and travel to niterói over the rio-niterói bridge.  

buses to niterói have their starting point in ipanema, on praça general osório, corner rua gomes carneiro very easy to find about 3 minutes walk from the beach at posto 8, and across the zona sul supermarket. 

leaving from ipanema, there are two companies offering the service between rio de janeiro and niterói - braso lisboa onibus, and auto viação 1001.