Abstract: The invention relates to an apparatus and method for extracting vibration data from a moving drive chain. In the preferred embodiment, the chain is that of a bicycle, or similar pedaled machine such as an indoor stationery bicycle, with two or more sensors placed on the chainstay of the bicycle to measure the vibrational frequency of the chain. Such vibration data can be used to determine the tension of the chain, and may also further compute the power transmitted by the chain, in conjunction with the measurement of chain speed. The invention provides a method and apparatus for conditioning and filtering the signals from the vibration sensors, as well as an arrangement for positioning the sensors on the bicycle.

Abstract: The invention broadly provides a method and apparatus for measuring the power output of one powering a chain driven vehicle. In a preferred embodiment described, the vehicle is a bicycle. The method of the invention comprises measuring the speed and tension of the drive chain and calculating the power output therefrom. The apparatus of the invention includes a chain speed sensor, a chain tension sensor, and electronic processing means to calculate and display the power output based upon the chain measurements.