The JMP Chain Check Gauge is a great tool for your workshop or to retail to bike owners.

It measures chain elongation in seconds and makes simple work of assessing wear in any chain from 420 – 530 pitch, covering the majority of popular models.

To check if a chain is excessively worn, make sure the chain is clean and properly tensioned. Use the centre measuring scale to measure the chain slack according to the specifications for the bike.

On 420 & 428 pitch chains the length of 15 links is measured.
On 520,525 & 530 pitch chains the length of 12 links is measured.

Always check in several areas around the length of the chain, but always do the check on the top run of the chain (above the swingarm).

Place the rounded end of the chain check gauge lightly against the chain roller, then lower the measuring tip. The chain elongation is indicated on the measuring tip where it touches the chain roller.

A chain is considered excessively worn if elongation is 1 % or more, then the chain should be replaced as soon as possible. While 1% may not sound much to a customer, it’s worth reminding them a typical chain can be around 1.8m long, so a 1% stretch is 18mm – that’s a lot of wear in the precision made, hardened steel pins and bushes of a modern chain.

It’s easy for chain wear to be ignored, but it can quickly lead to a breakdown or even the chain coming off which can have serious safety risks. With the JMP Chain Check Gauge, it takes seconds to check.

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