Happily the program is open to anyone with a credit card, and the bike reservation process sounds easy-peasy enough, provided you can access a loaner cell phone or pay phone. Treehugger explains the process:
People have to register in the website Mobilicidade.com.br with a credit card (in which you'll be charged a deposit of around 300 reais (about 150 USD). Then you pick a pass (daily, weekly, monthly or annual) and head to the point where you want to start. There you have to call the number on the pick up station panel and enter your security code, and a bike will be unlocked.
While this may be one way to ensure that you don't end up in a rough favela, sweating through your under-shirt passport wallet, we do hope you don't look at Sugarloaf and think "oh yea, I can totally bike that;" best to keep it to the stretches of beach.
· Samba [Official Site]
· Rio de Janeiro's Bike Sharing System, Appropriately called Samba [Treehugger]
· Bike Sharing Coverage [Jaunted]