A torque sensor for a human-powered object includes a spindle connecting crank arms of the object. In one embodiment, the object can be a bicycle. The torque sensor further includes at least one strain gauge mounted to the spindle in a shear pattern to measure shear strain perpendicular to a radius of the spindle. In some embodiments, the torque sensor further includes a carrier fixed to a hollow interior of the spindle, where at least one strain gauge is mounted to the spindle via the carrier. Advantageously, the torque sensor provides a low cost method to measure power.