Chain Comparison of Initial Stretch After 1000km Comparison of Chain ... O-ring chains. EK Chains new Zero Stretch Technology virtually eliminates ... measurable chain stretch in the first 1000km of use. ZST puts an ... break-in period, when most chain stretch occurs. For racers, this can mean going ... heattreated alloy steel to resist chain stretch. Pins are quad-staked to the sideplates ...