A battery assembly 51 for fitting a battery pack 52 to a frame of a cycle 2 comprises a battery holder 54 for fitting to the frame, and a connector portion 55 which forms an electrical connection between the battery pack 52 and wiring 90 for connecting to at least one other component of the cycle when the battery pack is held by the holder 54. The connector portion 55 is slideable in a linear direction with respect to the battery holder between an open position which provides clearance of the battery pack to be inserted into the holder and a closed position in which the connection is formed. A clamping mechanism is provided to clamp the battery pack into the battery holder when the connector portion is closed.