After my predecessor (Nike Air Zoom Structure 17) came in years, the switch to the new pair came. The old ones were tested on the treadmill and selected based on a running analysis. The four years later model could continue to be used without any problems. The shoes are mainly used for distances between 10 and 21 km and so far (about 150 km) nothing negative could be determined. It runs Pima on both tar and gravel and the cushioning is terrific.