A wheel-acting force measuring system for measuring for measuring force generated by a wheel having a road contacting surface is provided. The system includes an axle having a brake disk attachment portion and a spindle portion extending outwardly from the brake disk attachment portion to which the wheel is mounted, and a stress detecting sensor embedded in the spindle portion at a position between the brake disc attachment portion and a plane perpendicular to the road contacting surface of the wheel. In an embodiment there is further provided a brake caliper having a brake caliper angle defined by a caliper fixing axis and a wheel traveling direction, and the stress detecting sensor is mounted substantially at the brake caliper angle with respect to the wheel traveling direction and parallel to the caliper fixing axis.