Double-tapered tapered single-mode fibers are common in many telecommunications components, and provide an alternative sensor for typical fiber-optic strain gauges. They are susceptible to temperature and pressure and require expensive and complex signal acquisition systems. Cavity ringing spectroscopy is a technique commonly used in high-sensitivity chemical analysis. It has the advantage of detection sensitivity and can be used to improve double taper strain measurement. Combining these two technologies in a space-extending resonator, we demonstrate that the minimum detectable change in ringing time is 0.08%, corresponding to the minimum detectable displacement of 4.8 nm, and the sensitivity to strain at 5 Hz As small as 79nε / mm tapered length.