Wireless mesh networks offer promising solutions for extending the coverage of wireless local area networks along with increased communication reliability. The wireless mesh backbone serves as an access network for a large number of heterogeneous networks, providing them internet connectivity. Comprising of dedicated routers, the backbone differs significantly from conventional ad hoc networks due to lack of mobility and energy constraints. Classical ad hoc routing protocols developed for typical ad hoc networks, concentrate on mobility and energy conservation and their suitability and possible adoption for the backbone warrants careful evaluation. In this paper, we analyze the performance of four popular ad hoc routing protocols including two reactive (DSR, AODV) and two proactive (OLSR, DSDV) protocols for the mesh backbone using simulation. We provide results for routing overhead, packet delivery fraction and end-to-end delay metrics. Optimizations for these protocols are proposed and design directions for future backbone routing protocols are outlined.