Why Are My Bike Gears Skipping?

A skipping chain usually happens under load — climbing or sprinting — and ranges from occasional to almost every pedal stroke. Here's what causes it.

Most likely cause: worn chain

A stretched chain no longer meshes correctly with cassette sprockets. The result is skipping under load. Check with a £5 chain checker tool — if past 0.75% stretch, the chain needs replacing. Our chain wear guide explains this in detail.

Worn cassette

If you've been riding a worn chain for a while, cassette sprockets will have worn to match. Fitting a new chain on a worn cassette often causes more skipping — you need to replace both together.

Indexing out of adjustment

Gear cables stretch over time, throwing indexing out of sync. The derailleur sits between sprockets, making the chain skip or chatter. Fixed with a barrel adjuster — a quarter turn at a time until shifts are clean.

Bent derailleur hanger

The derailleur hanger is a small replaceable aluminium tab designed to bend in a crash, protecting the derailleur. Even a slight bend throws alignment off, causing erratic shifting across multiple gears. Very common and often overlooked.

Stiff link in the chain

A stiff link causes a jump every time it passes through the derailleur. Watch the chain slowly through the jockey wheels — you'll see it hesitate or jerk.

Frayed gear cable

A fraying cable causes inconsistent tension. If the cable is fraying at the anchor bolt or inside the housing, it needs replacing.

Quick self-check

• Skips on one gear? Indexing or worn sprocket. Multiple gears? Worn chain or bent hanger.
• Only under load? Worn chain or cassette.
• Regular click once per revolution? Stiff link.
• Bike dropped recently? Check the derailleur hanger.