Neurotransmission depends upon the fast axonal transport of synaptic vesicle precursors by the monomeric kinesin Unc104, a motor whose mechanism of action is a topic of debate. New work suggests that the formation of lipid raft domains triggers the assembly of vesicle-bound Unc104 dimers and the concomitant activation of processive movement, facilitating efficient long-range vesicle transport.