Abstract: A generator for a bicycle wheel comprises a core and a plurality of rotating yokes. The core has a first outer leg, a middle leg and a second outer leg, wherein an electric coil surrounds the middle leg. The core comprises at least one permanent magnet which is configured such that the first outer leg and the second outer leg of the core are magnetized in opposing directions. The yokes have a length which corresponds to the distance between the middle leg and one of the outer legs of the core. The yokes are arranged such that they pass subsequently along the first outer leg, the middle leg and the second outer leg of the core when the yokes are rotating, so that an alternating electric voltage is induced in the coil while a respective one of the yokes passes along the core.