A bike chain needs three things: clean it when it is visibly gritty, lubricate it so oil reaches the inside of the links, and measure it for wear so you replace it before it damages the cassette and chainrings. Most of the cost of neglect comes from the third step. Replacing a chain is cheap; replacing the cassette and chainrings along with it is not.
Why chains wear out
People say a chain “stretches,” but the side plates do not lengthen. As Sheldon Brown’s chain article puts it, the major cause of chain “stretch” is wear. The pins and bushings (the small cylinders the rollers turn on) lose material, so the spacing between links grows. A new chain has a pitch (the distance from roller center to roller center) of 1/2 inch (12.7 mm). Once that spacing grows, the links no longer sit properly between the sprocket teeth, and the teeth wear to match.
Dirt speeds this up. One general reference states that the lifetime of a chain depends mostly on how well it is cleaned and lubricated, not on how hard you pedal. That is the reason for the routine below, and why dry, clean-conditions mileage figures do not carry over to wet, gritty riding.
When to clean and re-lube
There is no reliable mileage interval, because it depends on weather, dust and the lube you use. Use condition-based triggers instead:
- The chain looks black and gritty, or a rag wiped along it comes away dark with grit. Clean before adding more lube, because new lube on a dirty chain mixes with the dirt.
- The drivetrain squeaks or sounds dry. It needs lube.
- You rode through rain, mud or road spray. Wipe it down and re-lube once the chain is dry.
How to clean a chain on the bike
- Put the bike in a stand or lean it where you can spin the cranks. Shield the wheels, brake rotors and rim brake surfaces with a rag or piece of cardboard.
- Apply bike degreaser to the chain while turning the cranks backward, or run the chain through a clip-on cleaning device filled with degreaser.
- Scrub the outside of the chain, the chainrings, the cassette and the derailleur pulleys with a brush.
- Wipe the chain with clean rags until they come away mostly clean. If you rinse with water, dry the chain fully before lubing.
- Let it dry before applying lube.
Keep degreaser and lube off brake pads and rotors or rim braking surfaces. If your brakes feel weaker or noisier after cleaning, do not ride the bike. Take it to a shop to have the brakes checked. For washing the rest of the bike, see How to Wash Your Bike Properly.
Disposing of used degreaser
Used degreaser and dirty solvent are household hazardous waste. The US EPA lists improper disposal as including pouring products down the drain, on the ground or into storm sewers, and advises contacting your local environmental, health or solid waste agency to find permanent or periodic collections near you. Do not tip a cleaning-device bath out in the street or yard. Rags soaked in solvent should also be handled according to your local guidance.
Choosing and applying lube
Put lube on the rollers while turning the cranks backward slowly, one drop per link, then let it soak in and wipe the outside of the chain dry. The lube has to reach the inside of the links, where the pins and rollers move. Lube left on the outside only collects dirt.
| Type | Strength | Trade-off |
|---|---|---|
| Wet (oil-based) | Liquid lubricants like oil penetrate to the inside of the links and are not easily displaced. | They quickly attract dirt, so wipe the outside after the oil has soaked in. |
| Dry | Stays cleaner in use. | Less durable and needs frequent reapplication. |
| Immersion wax | Stays cleaner in use and is reasonably durable. | Needs a thorough initial degreasing and setup. Re-waxing may be needed every 200-400 km depending on conditions. |
Two things to avoid: automotive motor oil, which contains detergent, and thin penetrating sprays such as WD-40, which Sheldon Brown notes are intended more as solvents than lubricants.
Checking chain wear
Measure wear at regular intervals rather than only when something feels wrong. Two common methods:
Chain-wear gauge
A gauge has a tooth-shaped end that is placed on the chain under light load. If the tooth drops in all the way, the chain should be replaced. Many gauges have two sides for different degrees of wear. A commonly cited conservative limit is 0.5% wear (24 half-links measuring 12 1/16 inches, or 306 mm), and replacement is recommended before 0.7% (20 half-links measuring 10 1/16 inches, or 256 mm). Follow the instructions that come with your gauge, since the limit it marks may differ by gauge and chain.
Replacing at the stricter 0.5% mark protects the cassette best. If you wait too long, a new chain will almost certainly skip on the worn sprockets.
Ruler
Measure a one-foot (30 cm) length by lining an inch mark up with the side of one link pin, then look at the pin 12 complete links away. In Sheldon Brown’s guidance, if that pin is 1/16 inch (about 1.6 mm) past the mark, replace the chain, and the sprockets are probably undamaged. At 1/8 inch (about 3 mm) past the mark you have left it too long, and the worn sprockets will cause a new chain to wear much faster than it should.
How long a chain lasts
Sources differ because conditions differ. One reference gives about 3,000 to 5,000 km (2,000 to 3,000 miles) for well-maintained derailleur chains, and as little as 1,000 km (600 miles) in harsh all-weather or cross-country use. Treat any mileage as a rough guide and let the gauge decide.
Replacing the chain and using a quick link
A master link, also called a quick link or connecting link, lets a chain be installed or removed without specialized tools. Match the link to your chain’s speed count, and use the model your chain’s maker specifies, since some chain designs, such as Shimano and Campagnolo 10-speed chains, require a special replacement pin if the chain is separated. Buying the right chain for your number of sprockets and fitting it to the correct length is the part to get right. If you are not sure about length, routing through the derailleur or whether the cassette should be replaced at the same time, have a shop do it.
If gears skip, shift poorly or the chain falls off even after a clean, lube and a new chain, see Why Your Bike Shifts Badly. A quick look at the chain is also part of the 5-minute pre-ride checklist.
Sources
- Sheldon Brown: Bicycle Chains
- Sheldon Brown: Bicycle Chain and Sprocket Engagement and Wear
- Wikipedia: Bicycle chain
- US EPA: Household Hazardous Waste
Last reviewed: October 2026.