As a case study about İzmir (the third biggest metropolitan city in Turkey), this paper focuses on how to determine bicycle routes in already developed built environments of densely populated cities. To do so, it identifies how to deploy certain geographic information system (GIS) tools for analyzing multilayered spatial data not only at the city but also at the neighborhood level. When interrelating multiple characteristics of majorly topography, land use and population with each other, the study deploys mainly the overlay analysis and also network analysis as complementary to each other respectively at the city level and the neighborhood level. The results confirms that the use of these GIS tools for analyzing socio-spatial data especially at multiple spatial scales can support policy-makers' decision-makings about route choices in the immediate future of their city even in a "data-poor" context," such as Turkey.