Traffic space is a scarce resource in urban environments. Increasing density of road users, combined with limited available infrastructure, forces us to optimize the efficiency of the use of space by means of transport. This paper presents a mathematical model that investigates the relationship between the number of wheels on bicycles and the amount of traffic space occupied, with the aim of minimizing this space. The reasoning leads to the conclusion that the optimal number of wheels is ultimately negative, which has interesting theoretical implications for the design of future means of transport.