A rotation sensor configured to be mounted on a rim of a wheel. The rotation sensor includes a band sized and shaped to fit around the rim of the wheel, a first element mounted on the band that generates a first time-varying electrical signal in response to a rotational movement, a second element mounted on the band that generates a second time-varying electrical signal in response to the rotational movement, a processor mounted on the band that receives the first and second time-varying electrical signals and processes the first and second time-varying electrical signals to determine a rotational speed, and a rechargeable power source that receives the first and second time-varying electrical signals, consumes at least a portion of the first and second time-varying electrical signals to recharge the rechargeable power source, and generates a power signal. The processor is connected to the rechargeable power source to receive the power signal.