The chain is not a Slinky. It dosen't stretch under load unless you measure down to the billionths of an inch (I'm not even sure if it does at that level either) I don't care how hard you think you pedal. The links will not pull apart and allow the masterlink to mysteriously lose tension and fall apart while you are apply force at the "superhuman" level. Chain stretch is not chain stretch but chain wear, on the pins, over time.