Cycling is a very popular form of transport in the most developed European cities (the example of Amsterdam). Its development is encouraged because it contributes to the preservation of the environment, promotes a healthy lifestyle and is a very cheap form of transport. The City of Zagreb, despite the positive developments, doesn't have a sufficiently developed and infrastructurally equipped bicycle network, although this would encourage people to use it (especially the younger population). This would reduce congestion of other forms of traffic (especially automobile traffic). The paper proposes the main routes where the development and investment in cycling infrastructure would be most needed. The routes are: Route West - East, Route North - South, Central route and Student route. Not only because they are following the busiest roads in Zagreb, the routes were chosen because of other characteristics that will be described in the paper. For each route is described the condition of the cycling infrastructure and solutions for its improvement are proposed. Also, each route is shown cartographically. Data on the condition of individual bicycle route was obtained through fieldwork. At the end of the paper, the planned cycling projects of the City of Zagreb are described.