Abstract: An apparatus for the measurement of centrifugal forces generated by a rotary member such as a vehicle wheel which is out of balance, comprises a rotary member mounting for supporting the rotary member with respect to an apparatus frame structure. The rotary member and the rotary member mounting form a sub-critical oscillating system in measurement of the rotary member which rotates for a measuring procedure. The apparatus further includes a measurement sensor which is in the form of a force pick-up and whose direction of application of force extends approximately tangentially to a circle through the location of the application of force at the measurement sensor, around a virtual mounting location.