A gear for use in a transmission system. The gear comprises an outer annular element having gear teeth on a radially outer surface thereof and an inner support element arranged coaxially with the outer annular element. The gear further comprises first and second opposing side walls, each side wall extending from the outer annular element to the inner support element to form an annular space. At least one of the first and second side walls extends from the outer annular element at an angle greater than 0 degrees with respect to a direction perpendicular to the rotational axis of the gear.