How to Fix a Bike Chain Slipping

Overview

A slipping chain is dangerous and can damage your bike. This guide covers fixing a slipping chain.

Step-by-Step Fix

1. First, inspect your chain for wear using a dedicated chain checker tool; you can usually buy these at any bike shop. Place the tool onto your chain and if it sinks past the 0.75% or 1.0% mark (check your tool's instructions), your chain is worn and needs replacing. A worn chain can lead to poor shifting and premature wear on other components, so this is a crucial first check.
2. Next, carefully examine the teeth on your rear cassette for any signs of wear, particularly 'shark fin' shapes where the teeth appear pointed and hooked rather than square or rounded. Spin your wheel slowly whilst looking closely at each sprocket, paying extra attention to the ones you use most often, as these will show wear first. If multiple teeth appear noticeably thin or hooked, your cassette is likely worn and will need to be replaced to ensure good chain engagement.
3. If your chain checker indicated significant wear, you must replace the old chain with a new one; ensure it's the correct speed (e.g., 9-speed, 10-speed) for your bike. Use a chain tool to remove the old chain and fit the new one, making sure the direction is correct if it's a directional chain, and then secure it with the appropriate master link or pin. Always double-check the master link is fully seated and locked before riding, as a faulty link can be very dangerous.
4. Should your cassette show clear signs of wear, or if you've fitted a new chain and it still slips, you'll need to replace the cassette. Use a cassette lockring tool and a chain whip to remove the old cassette from the freehub body, then carefully slide the new cassette onto the freehub, ensuring the splines align correctly. Tighten the lockring firmly with the cassette tool to the manufacturer's recommended torque, if specified, to prevent it from loosening during use.
5. Finally, once any new components are fitted, take your bike for a short test ride and apply firm pressure to the pedals, especially when going uphill or accelerating, to simulate typical riding conditions. Observe closely if the chain slips or jumps under this load, particularly on the sprockets you identified as potentially worn, and listen for any unusual noises. If the chain still slips after these steps, it might indicate issues with your front chainrings or derailleur adjustment, which would require further investigation.

Common Symptoms & Diagnostic Resolutions

Review the common error codes and operating symptoms below to quickly identify the root cause of the fault before ordering replacement parts.

Frequently Asked Questions