Bbb chain checker btl51all about cycling bbb think of the details so you dont have to founded by a former road racer they continue to make products with the explicit understanding of what makes a proper bike product that only a rider could have features easy to use chain wear checking tool when the 075 75 wear is reached the chain must be replaced soon when the 10 100 wear is reached the chain must be replaced instantly buy bbb chain tools from chain reaction cycles the worlds