Unior chain wear indicatora worn chain shifts poorly and causes undue damage to the sprockets this tool is a go no go gauge designed to accurately indicate when a chain is worn out it is made from precision laser cut steel for accuracy features made from precision laser cut steel measurement 0 0 6 no chain wear 071 2 the chain is worn out and it is necessary to replace it buyunior workshopfrom chain reaction cycles the worlds largest online bike store