We would like to rent bikes and tour around Central Park from top to bottom (or other way around) stopping now and then to see Belvedere Castle, Strawberry Fields, fountains, gardens, etc. We are going in early August so it will be hot and was wondering if a 2 hour bike rental was sufficient time or if 3 hours made more sense. Don't want to feel rushed but may return on foot to some areas too. We are only in NYC for 4 1/2 days. thanks for your thoughts.