Abstract: A hub and dynamo arrangement includes a wheel hub rotatable about the axis of a fixed shaft; a dynamo having an annular stator carried by the hub, an annular armature disposed radially inwardly of the stator and a current collector fixed to the armature for leading off current generated by the dynamo, the armature being mounted for rotation about the axis of the shaft independently of the hub; a control device for selectively arresting and permitting rotation of the armature about the axis of the shaft, whereby electric current is generated when the armature is arrested, the control device including a contact member mounted for radial movement relative to the axis of the shaft and mounted in a position such that the radial movement effects current-transmitting and rotation-locking engagement with the current collector; and an electrically-conducting, actuating wire attached to the contact member, both for transmitting current from the contact member, and for applying mechanical actuating force to the contact