— A growing number of cities worldwide have been installing public bike sharing systems, offering citizens a flexible and “green” alternative of mobility. In most bike sharing systems, customers rent and return bikes at different stations, without prior notification of the system operator. As a consequence, bike systems often become unbalanced, leaving some stations either empty or full. In such a case, customers either cannot pick up or return their bikes, resulting in a low service level. Typically, system operators employ staff to manually relocate bikes using trucks, leading to considerable operational cost. In this paper, we describe various methods to balance bike sharing systems by actively engaging customers in the balancing process. In particular, we show that by appropriately sending “control signals” to customers requesting them to slightly change their intended journeys, bike sharing systems can be balanced without using staffed trucks. Through extensive simulat...