A caster-wheel assembly (100; 200) for a vehicle, for example a wheelchair or powered wheelchair. The caster-wheel assembly comprises a switch (13) coupled to a housing (3); a castering wheel bracket (9) configured to receive a wheel (10), wherein the bracket is rotatably mounted about a caster pivot axis (28) with respect to the housing; biasing means (15) configured to provide a biasing force such that the wheel bracket is biased away from the housing; and a switch-actuating member (13) coupled to the wheel bracket such that movement of the wheel bracket towards the housing and against the biasing force causes the switch-actuating member to actuate the switch.