Complex Event Processing (CEP) consists in processing events happening across all the layers of an organization, identifying significant ones or meaningful combinations of those events and launching managing rules as a reaction. In this work we propose to use Complex Event Processing (CEP) as a supervision method for bike hiring services. The idea is to use CEP as a monitoring strategy. The events are generated by the system when users pick up or leave bikes from /to the depots distributed across the city. CEP allows describing the behaviour of the overall cycling system as a set of events, complex events and rules. It can monitor users' behaviour and trigger alarms in order to apply the corresponding billing penalties. Our CEP prototype has been tested using data extracted from the Barcelona cycling (Bicing) system. The preliminary results show he benefits of using such technology for monitoring purposes in distributed environments as the public cycling transport.