Symptoms
- Chain audibly skips or slaps under acceleration
- Chain looks rusty, dry, or has stiff links
- Sprocket teeth look hooked or worn to a point
Likely causes
- CommonChain and sprockets worn out togetherA stretched chain and worn sprockets wear together, and mixing old and new parts causes rapid re-wear.
- CommonChain slack too loose to stay engaged properlyExcess slack lets the chain jump on the sprocket teeth under load.
- PossibleBent or damaged linkA single tight or bent link can cause repeated skipping at that point in the chain's rotation.
What to do
- Check chain slack first, since a simple adjustment may resolve minor skipping if the chain isn't badly worn.
- Inspect the sprocket teeth visually; worn teeth often look hooked or shark-fin shaped instead of straight.
- Look along the entire chain for any stiff or kinked links that don't flex smoothly.
- Pull the chain away from the rear sprocket at the back; if it lifts away more than about half a tooth's height, it's stretched and needs replacement.
- If both chain and sprockets show significant wear, replace them as a set rather than mixing old and new parts.
- After replacement, set initial chain tension per the manual and recheck after the first short ride as new chains settle slightly.
Tools and parts
- Wrench set
- Chain breaker/tool (for replacement)
Chain and sprocket kit sized for your bikeSearch: “chain and sprocket kit for [your bike year make model]”
When to call a pro
If you're not comfortable setting chain tension and alignment precisely, have a shop install and set up a new chain and sprockets.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.