there are no public buses going to praia da macumba, thus the best option would be getting to praia do recreio and walk from there (about 30 minute walk) or taking a taxi for about 100 reals from zona sul - a return trip should be booked in advance as there are usually no taxis driving through this area.

alternatively, praia do pontal is fairly easy to reach via bus from ipanema or copacabana, as the bus line 523 (alvorada x leme via copacabana) rides along copacabana and ipanema - the ride is about 60 to 80 minutes long, depending on traffic conditions, and gets to estrada vereador alceu de carvalho, which is the closest point to praia da macumba at about 1500 meters.     

a great option when available is the surf bus,  a special private bus taking visitors from zona sul to all the main surf beaches in rio, including barra beach. the surf bus leaves from largo do machado every day at 7 am, 10 am,1 pm, and 4 pm. more details are posted on their webpage.