Cities all over the world struggle with air pollution. With the ever-increasing concentration of people in urban areas, more and more people suffer from the negative effects of air pollutants. Crowdsensing systems are a unique chance to increase the users’ awareness of this problem and to provide more fine-grained data to policymakers so that they can adopt appropriate strategies. In this paper, we present a crowdsensing system to collect air pollution in urban and suburban environments through the use of bicycles. It consists of a Web application, enriched with gamification elements, that communicates with a portable low-cost sensor. The user interface of such a system, as well as the adopted gamification mechanisms, has been designed by involving a group of target users, with the aim of better meeting users’ preferences and needs, and, then, better engaging them.