How to Check Your Chain for Wear

In plain English

Chains "stretch" as their pins and rollers wear. A worn chain wears out the cogs and chainring, and those cost much more than a chain. E-bikes, and mid-drives especially, wear chains faster than normal bikes, so check often.

Watch how it's done

Video by Park Tool. It may show a regular bike: on an e-bike, switch off and remove the battery first, and unplug the motor cable before taking off a hub-motor wheel.

Work from the top. Steps go from free and easy to shop jobs. Switch the bike off before touching any connector. Tick each step as you go. Your progress is saved on this device.

1. 1Check every few hundred milesFree E-bikes wear chains faster, so check regularly, and right away if the chain starts skipping.
2. 2Use a chain checkerEasy Drop the checker's ends into the chain. Most checkers show two marks, usually 0.5% and 0.75%. Many guides say to replace at 0.5% on 11- and 12-speed bikes and at 0.75% on others. Follow the instructions on your checker.
3. 3Replace the chainModerate Buy a chain for your number of gears, count the links to match the old chain, and join it with the quick link or pin it came with. A shop can fit it if you'd rather.
4. 4Have the gears and chain checkedShop job A shop can straighten a bent derailleur hanger, set the gear limits and replace worn chains and cassettes.

Parts you might need

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Only buy a part if the free steps didn't fix it. Always match the voltage and connector type to your bike.

• Chain wear checker

  A small gauge that tells you when a chain is worn out.

  Link coming soon

• Bike chain

  Match the number of gears on your bike (for example 8-speed). E-bike rated chains last longer.

  Link coming soon

• Chain lube

  Keeps the chain quiet and stops wear. Use bike chain lube, not household oil.

  Link coming soon