Central Park is so big a bike is really needed to see it. It isn't flat though. The rental process was without a problem. Hired a bike for 4 hours but had had enough in 3. The 4 hour rental was good value though.
This was a great bike deal. Two hours was enough to get around Central Park and make a few stops. The loop around Central Park has some hills so families with young children may need another hour.
Biking Central Park is an absolutely amazing thing to do. Just not with this guys. They gave me a dirty helmet with the bike and failed to provide me with a basket and a lock even though it was specifically included in the price. To end up the bad experience with them, I asked for using their bathroom for washing my hands, face and changing clothes for fresh ones up (it was a rainy day and got some mud). They refused my request by ridiculously telling me they didn't had one and sending me over a closed restaurant. By all means go and rent a bike for exploring Central Park. Just not with them.