Chain Waxing

OK, that’s enough fun for now. 0.75 chain checker still not dropping in, but measures 1/16 over on a steel rule. Sheldon says that is time to change chain before sprockets become worn.

let's look at how to do this with a ruler that measures in inches.

• If the link pin is less than 1/16" past the mark, all is well.
  
• If the link pin is 1/16" past the mark, you should replace the chain, but the sprockets are probably undamaged.
  
• If the link pin is 1/8" past the mark, you have left it too long, and the sprockets (at least the favorite ones) will be too badly worn.
  If you replace a chain at the 1/8" point, without replacing the
  sprockets, it may run OK and not skip, but the worn sprockets will
  cause the new chain to wear much faster than it should, until it
  catches up with the wear state of the sprockets.
  
• If the link pin is past the 1/8" mark, a new chain will almost certainly skip on the worn sprockets, especially the smaller ones.
  

https://www.sheldonbrown.com/chain-wear.html