Love this bike rental place along Pampulha lake. They've recently redone the layout and it now has…read more a much more welcoming feel; there are benches to sit, some vegetation to catch some shade, and a cafe for drinks, fresh coconuts, and food. And then of course there are the bikes. They are a bit clunky / heavy but they rent for just R10 per hour. Bikes with gears, family tricycles, and other contraptions are also available. The renting itself is very easy and a smooth process.
All in all this BikeMania location is an excellent option if you're looking for some "active time" along lake Pampulha. There are bike lanes around most of the lake. Note that a ride around the entire lake is 18km long - make sure to pack some water and sunscreen because it can become a bit of a slog on these rental bicycles.