The aim of this work is to compare the logistics of urban light weight delivery by motorcycle and bicycle. To this purpose, a case study in the city of Curitiba, Brazil, was chosen. City planning demands alternative solutions to everyday problems, among which use of urban space and mobility are relevant due to fast and rather chaotic growth. Urban mobility − a complex network comprising a variety of actors and areas -has social, economic and environmental impacts that might be underestimated in planning and implementation of actions. So far, and for the case studied here, urban planning for light weight delivery has not included externalities, but rather focused on the technical issues of logistics and urban traffic. For instance, the rates of death and disability from accidents on this mobility are currently very high. In the present research, two light weight deliveries actually used in Curitiba were compared: motorbikes and bicycles. The analysis is based on the methodology of the eco-socio-economy of organizations. This approach considers the complexity of linked subsystems, and the effectiveness beyond the organization but on the social demands in the urban territory. The use of bicycles was studied using data from EcoBike, analyzed here and compared to the generic case of deliveries by motorbikes. Indicators for accidents (with and without death), fossil energy used, CO2 emissions, and operative costs were obtained and compared. The indicators assessed favour the use of bicycles over motorbikes.