A drive system (50 for rotating a wheel of an aircraft landing gear, the drive system including: a motor operable to rotate a drive pinion via a drive path; and a driven gear adapted to be attached to the wheel so as to be capable of rotating the wheel, wherein: the drive system has a drive configuration in which the drive pinion is capable of meshing with the driven gear to permit the motor to drive the driven gear via the drive path; characterised in that one of the drive pinion and the driven gear comprises a roller gear having a series of rollers arranged to form a ring, each roller being rotatable about a roller axis, and the other of the drive pinion and the driven gear comprises a sprocket; the drive path comprises a first compensating gear and a second compensating gear which meshes with the first compensating gear; and the drive system is configured such that, when the motor drives the driven gear via the drive path in the drive configuration, there is a first oscillation in torque transmitted from the drive pinion to the driven gear and a second oscillation in torque transmitted from the second compensating gear to the drive pinion via the first compensating gear and the common drive shaft, the second oscillation tending to counteract the first oscillation. a motor operable to rotate a drive pinion via a drive path; and a driven gear adapted to be attached to the wheel so as to be capable of rotating the wheel, wherein: the drive system has a drive configuration in which the drive pinion is capable of meshing with the driven gear to permit the motor to drive the driven gear via the drive path; characterised in that one of the drive pinion and the driven gear comprises a roller gear having a series of rollers arranged to form a ring, each roller being rotatable about a roller axis, and the other of the drive pinion and the driven gear comprises a sprocket; the drive path comprises a first compensating gear and a second compensating gear which meshes with the first compensating gear; and the drive system is configured such that, when the motor drives the driven gear via the drive path in the drive configuration, there is a first oscillation in torque transmitted from the drive pinion to the driven gear and a second oscillation in torque transmitted from the second compensating gear to the drive pinion via the first compensating gear and the common drive shaft, the second oscillation tending to counteract the first oscillation. the drive system has a drive configuration in which the drive pinion is capable of meshing with the driven gear to permit the motor to drive the driven gear via the drive path; characterised in that one of the drive pinion and the driven gear comprises a roller gear having a series of rollers arranged to form a ring, each roller being rotatable about a roller axis, and the other of the drive pinion and the driven gear comprises a sprocket; the drive path comprises a first compensating gear and a second compensating gear which meshes with the first compensating gear; and the drive system is configured such that, when the motor drives the driven gear via the drive path in the drive configuration, there is a first oscillation in torque transmitted from the drive pinion to the driven gear and a second oscillation in torque transmitted from the second compensating gear to the drive pinion via the first compensating gear and the common drive shaft, the second oscillation tending to counteract the first oscillation.