Electrical switch unit for a bicycle

An electrical switch unit (20) for a bicycle is adapted to be removably attached to a brake member bracket (5). The brake member bracket (5) includes a switch mounting recess (23) in which the switch unit (20) is detachably located. The switch unit (20) optionally includes a seal member (37) to seal a gap between the switch unit (20) and the brake member bracket (5), and a push button on the unit controls a switch on a cycle computer.