Chain

The chain carries drive force from the chainring to the rear cogs. It wears gradually, which shows up as "stretch".

What it's used for

A worn chain meshes poorly, shifts badly and wears the cogs and chainrings faster. Park Tool notes a new cassette costs much more than a new chain, so replacing the chain on time saves money (Park Tool chain wear guide). Park Tool's general replacement points are 0.75% wear for 10 speed or fewer and 0.5% for 11 speed or more, though makers set their own specs (Park Tool).

What to look for

• A chain that matches your drivetrain's speed count. Check your bike's manual or the drivetrain maker's site.
• The right joining part. Park Tool says each connecting rivet is specific to the chain's make and model, and some chains use a master link instead (Park Tool chain replacement).
• The right length. Size the new chain against the old one, unless the old one was wrong (Park Tool).

Using it safely

• Measure wear with a Chain checker rather than guessing.
• Clean and lube the chain regularly. Park Tool notes that on some mid-drive e-bikes the chain does not move when you backpedal, which changes how you clean it (Park Tool e-bike tools).
• After fitting, check for tight links and make sure any rivet sits flush with its neighbors (Park Tool).
• Skipping after a chain change can mean a worn cassette (Park Tool).

Best price we found

• KMC e8 EPT e-bike chain, 8 speed, 122 links, at KMC's own US store: $31.35 on sale (regular $41.80), checked Nov 9, 2026
• KMC e8 EcoProteQ chain, 8 speed, 122 links, at Performance Bicycle: $41.80, checked Nov 9, 2026 (back order)

Both are 8 speed chains. Match the speed count of your drivetrain. Prices change often, and a local shop may match them.

Guides that use it

• Check and replace a chain
• Clean and lube a chain
• Adjust a rear derailleur

Sources

• When to replace a chain on a bicycle, Park Tool
• Chain replacement: derailleur bikes, Park Tool
• What tools do I need for my e-bike, Park Tool
• KMC USA store: e8 EPT chain $31.35
• Performance Bicycle: KMC e8 EcoProteQ chain $41.80