I bought a TL-CN42. The instructions are vague. I inserted the double toothed end between 2 rivets. The single toothed end then rests on another rivet, BUT if I push down lightly, it will go between rivets. Is it time to replace? This is a 9.5 month old, 10 cog cassette, touring bike with about 2,700 miles, 95% on roads or paved trails.


According to this PDF I found it seems that your chain still has life left in it. It's when the ping drops between the pins that your chain has stretched too much.

This is pretty good: 2700mi is about 4400km which is approaching the expected lifespan of a chain (5000km). I've had decent chains which haven't lasted nearly that long. (Admittedly I do occasionally ride in wet weather.)

(Apologies for getting this messed up earlier.)

  • For all chain tools I've used in the past a 'single ping not dropping between the rivets' is an indication of the chain being fine and NOT worn (enough to replace it). Is the Shimano chain tool different? (I agree that 2700mi is not bad for a chain) Aug 31 '19 at 13:19
  • 1
    @TerrySeidler You're right; I messed that up. Thanks for the correction.
    – DavidW
    Aug 31 '19 at 14:21
  • Thanks. Those pictograms came wih the package, but I thought the bottom right picture in graphic 2 meant don't measure the chain when it is slack. Apparently, it means, don't push down.
    – user45143
    Sep 1 '19 at 0:08

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