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How to Check the Chain's Elongation

Digital Chain Checker


KMC has developed a special digital chain wear indicator, the ‘Digital Chain Checker’. This tool allows you to exactly measure the chain's elongation, changing the chain on time (not too early and not too late ) . It can help you to increase the service to customers and convince them that it's time to change chain to prevent excessive ware down of Chain wheel and cassette, and unnecessary high repair costs.

How to Check the Chain's Elongation

1. The easiest way of checking: when you feel the chain has lost its smooth running and agile shifting function.
2. A rough way of checking: put the chain on the outer chain ring, and lift up the chain from the middle of the ring; If you can lift it more than half a link, the chain or chain ring are probably worn.
3. A simply way of checking: use KMC Easy Chain Checker
4. A smart way of Checking: use KMC Digital Chain Checker

In general KMC recommends checks at the following intervals:
1.Road use and riding in the dry: every 500 kilometers (300miles).
2.Off road use or more demanding environments: every 150  kilometers (100miles).
Note: The chain life varies; it depends on the product you use, the circumstances you ride under and the maintenance you adopt. And avoid extreme shifting positions (as below)!

Connecting Link Instructions - Bullet Type Connecting Pin

Bullet Type Connecting Pin



  • Connect both ends of the chain with the special connecting pin.(Fig.1)
  • Put the chain on the Chain tool and tighten the adjustment nut.(Fig.2)
  • Use a Chain tool and turn the rotating bar to advance the special connecting pin into the chain. Next, loosen the adjustment nut and remove the chain.(Fig.3)
  • Use pliers to break off the excess part .(Fig.4)

Be sure to check that the connecting pin protrudes uniformly from both sides of the chain after the chain has been joined.

Connecting Link Instructions - Offset Link (Half Link)

Offset Link (Half Link)




  • Step 1: Connect the ends together.
  • Step 2: Use chain tool to pressure the pin in

Be sure to check the connecting pin protrudes uniformly form both sides of the chain after the chain has been joined. 

Connecting Link Instructions - Snap-On Connector

Snap-On Connector




  • Connect both ends of the chain with pin link. (Fig.1-A)
  • Place Snap-lock outer plate (Fig.1-B) over rivets of pin link (Fig.1-A) and bend chain
  • Gently towards you until the snap-lock plate clicks in. (Fig.2)

Connecting Link Instructions - Spring-Clip Connector

Spring-Clip Connector




  • Connect both ends of the chain with pin link.(Fig.1-A)
  • Close chain on the front side by placing the outer plate (Fig.1-B) and securing with spring clip (Fig.1-C) (Fig.2)
  • The closed end of the spring clip should always be mounted in the direction of the chain travel (Fig.3)

Connecting Link Instructions - Slotted Link

Slotted Link



1. Feature: Easy installation without hand tool and we recommend to use it in bike production line.

2. Installation:

  • Place two pins of the connecting link through two holes from each end (roller link ends) of the chain and loop up the chain. (Fig.1)
  • Line up circular notch with pin and sung down to pin groove, then slide the slotted plate across to the end. (Fig.2&3)
  • Turn this slotted plate and place the larger opening over the other pin. (Fig.4)
  • With fingers press firmly on the slotted plate. This slotted plate should snap shut tightly upon two pins while bending chain inward. (Fig.5&6)

Connecting Link Instructions - Missing Link

Missing Link


1. Closing
Fit chain, bring the ends together and insert both halves of the Missing Link into the chain ends.
Press both halves of the Missing Link connector together and lock in place by pulling the chain apart.

2. Opening
Press both plates of the Missing Link connector together while sliding the chain ends together (unlock). Remove the two halves of the link from the chain ends.

3. Caution
Always use a new Missing Link when fitting a new Chain. Failure to shorten the chain properly or to lock it exactly into place may cause damage to the chain and eventually total chain failure, material damage or the rider to fall off his bicycle resulting in injury.

4. We suggest using KMC's MissingLink connector and Remover tools for added safety and convenience.


Check shifting condition after riding

When prepare to stop riding, shift to small chainring before riding stop. This may avoid having to shift from stand-still and prevents unnecessary chain wear.

Can I use same link to disconnect and assemble chain?

When chain is assembled, at the pin link, pin is press-fit with outer plate. In order to mitigate the negative impact of press fit, please using different link to disconnect chain and assemble it together.

Special attention for installation?

For high end chain, pins are riveted with capping to sustain more sideways force during gear change. For this type of chain, pin can not be reused. To reconnecting chain, special pin with guide or special quick connecting link designated by chain makers has to be used.

For a regular non-capping riveted chain where reusing pin is not prohibited, after applying the lubricant, using the chain tool to reconnect the chain, bent the chain sideways back and forth for few times to make sure that there is no tight link at this connecting point.

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