In this paper, we propose a new mechanism, called the Spiderman Handover, for enabling Wi-Fi technology to support high speed mobility. It introduces two new 802.11 operational modes: the Spiderman mode and the Wireless Switch Access Point mode. We describe its operation, highlighting the Spiderman Handover and the Gratuitous ARP Loop routing update procedure as key elements for providing seamless horizontal handover for high-speed vehicles such as trains. We discuss and evaluate its operation theoretically and by means of simulation, concluding that the proposed mechanism is able to provide track-side connectivity with virtually no packet loss while keeping the observed latency invariant to the handover frequency.