Patent ID: 7975561

Claim:
A chain ring torque sensing assembly for use with a bicycle, the bicycle including a plurality of power input components including a crank arm and one or more chain rings, the assembly comprising: a sensor ring having a first set of mounting points on the sensor ring for coupling to a first one of the power input components and a second set of mounting points on the sensor ring for coupling to a second one of the power input components such that the sensor ring is positioned between and interconnects the first and second power input components through the first and second mounting points, wherein the first and second mounting points are at a common radius relative to a center of the sensor ring, and wherein the sensor ring has a closed body and includes at least one force transmission area defined at least in part by a void area in the sensor ring; and at least one strain sensor associated with the at least one force transmission area of the sensor ring and adapted to measure strain in the force transmission area resulting from power applied to the crank arm by a cyclist during riding of the bicycle.