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. 

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

exact schedules and itinerary can be seen on this page by braso lisboa, and on this page by auto viação 1001.