How to Repair a Bicycle

How to Clean and Replace a Bicycle Chain

To open a 1/8-inch chain's master link, pull out the retaining clip and remove the straight side plate.

Exposed to dirt and constant stress, a bike chain takes a licking. Give it a checkup every season to keep it working smoothly.

Tools: needle-nose pliers or chain rivet extractor, shallow pan, small stiff brush or toothbrush, chalk.


Materials: kerosene, motor oil, rags, replacement master link or replacement 1/8-inch or 3/32-inch bicycle chain.

Time: about 1/2 to 1 hour, plus drying time.


Single-speed and 3-speed bikes use a 1/8-inch chain with a master link; 5-speeds and 10-speeds use a 3/32-inch continuous chain. Both types should be cleaned regularly. Examine the way the chain is installed on the bicycle, and sketch it if you aren't sure you can remember it. You must replace the chain exactly the same way after you clean it.

Remove the chain from the bicycle. The master link of a 1/8-inch chain has straight side plates. To open the master link, pull out the retaining clip with a needle-nose pliers; then remove the side plate. Pull the link out of the chain to release the ends. To remove a 3/32-inch chain, push out a chain pin rivet anywhere along the chain. Align a chain rivet extractor with its screw pin over a rivet; tighten the screw of the extractor just enough to push the rivet through the center of the chain but leave it hanging from the far side. The chain will separate as the rivet is loosened.

Immerse the chain in kerosene in a shallow pan. Scrub it firmly with a small stiff brush or toothbrush to remove all dirt and old oil, and hang it to dry for about 1 hour. Immerse the cleaned chain in motor oil, remove it, and wipe off the excess oil with rags. Let the chain dry until it stops dripping.

To reinstall the chain, replace it around the rear sprocket and the front chainwheel, exactly as it was before you removed it. Reattach the master link to the loose ends of a 1/8-inch chain; replace the side plate and the retaining clip. Rejoin the ends of a 3/32-inch chain with a chain rivet extractor; loosen the screw pin, align the pin over the loose rivet where the ends of the chain meet, and tighten the screw pin. Adjust the rivet carefully so that it's exactly flush with both sides of the chain.

Check the chain tension to be sure it's correct; the wrong tension can be dangerous. On a derailleur bike, chain tension is adjusted automatically; if you think the tension is wrong, take the bike in to a shop. Single-speed bikes and 3-speed bikes with gears in the hub can be manually adjusted.

Open a 3/32-iinch chain at any link; push out a chain pin rivet with the pin of a chain rivet extractor.

Set a yardstick flat across the tops of the rear sprocket and the chainwheel. At the midpoint of the chain between the two sprockets, the top length of chain should sag about 1/2 inch below the bottom of the yardstick. Adjust the chain tension as necessary. Loosen the nuts on the rear wheel axle and move the wheel forward or back until the sag is correct; then tighten the axle nuts.

Damaged or Broken Chains

If a 1/8-inch chain comes apart at the master link, replace the master link with a new one. Adjust the chain to position it correctly, hook the new master link through the loose ends, and fasten the link. A chain that is damaged or breaks in the middle, or a damaged or broken 3/32-inch chain, should be replaced. Remove the chain as above and take it with you to the bike shop; buy a new chain of the same type.

To fit a new chain to the bicycle, remove links as necessary to adjust the chain to the proper length. If the old chain is in one piece, measure the new chain to this length and mark it with chalk. If you can't measure by the old chain, check chain length by stretching the chain into place around the rear sprocket and the front chainwheel, exactly as the old chain was installed, with the two ends meeting at the front chainwheel. Adjust the chain to the proper tension as above and slip the ends onto the sprockets of the wheel to mate them exactly; mark the exact link where the end link on one side meets the other side of the chain.

Remove any excess links from the end of the new chain with a chain rivet extractor. Replace the chain around the rear sprocket and the front chainwheel and join the ends with the master link or the chain rivet extractor. Be sure the connecting rivet is flush with both sides of the new chain.

Check chain tension by setting a yardstick flat across the sprocket and chainwheel; at its midpoint, the top length of chain should sag 1/2 inch below the yardstick. Adjust the chain as necessary to this tension.

Broken spokes are another bike part you may need to replace from time to time. Learn how to make this easy repair on the next page.

For tips on caring for and repairing other types of sports equipment, try the following links: