Fix a Broken Bicycle Chain

If you have a chainbreaker tool, also called a chain tool, then fixing a broken bicycle chain is easy. You can do most routine maintenance by yourself, however, you should know that after a chain breaks you should consider getting a new chain shortly after repairs.

Steps

Fixing the Chain without a Spare Link

  1. Take a picture, draw out, or memorize how the chain is currently attached. Note how it moves in and out of the pulley wheels, if there are any. Chains wrap around the derailleur (shifting device in the back of the bike) in a particular, but not difficulty to understand, patter you'll need to replicate later. Some chains are simply threaded on the gear.
    • If you work carefully you won't even need to remove the chain from the bike. But, depending where the link broke, there is a chance it slips off while cleaning or fixing. Take a quick picture now.
  2. Shift the bike into the middle gears in both the front and back, noting which gears you're on. The broken chain won't move, but the bike will be in soft, easy gears when you get it back on, as the extreme gears are the ones that tend to cause the chain to snap if it is weak.
    • If you only have one set of gears on this bike, you'll need a new chain link to proceed. The following method shortens the chain by a link, meaning it likely won't fit on your gears when finished.[1]
  3. Remove the broken chain and clean it with a degreaser and water. Use a toothbrush to get into the chainlinks, scrubbing off grime, rust, and dirt. A dirty chain is under much more stress than a clean one, and is much more primed to break. Clean it so that the chain links can move freely in your hands, paying attention specifically to any "stuck" or slow moving links. Clean the chain now to prevent fixing it again shortly.
    • If, even after cleaning, the chain is still rusty and stiff, you'll likely need a new chain. A rough, stiff chain can even damage your gears and derailleurs if left on for too long.
  4. Use a chainbreak tool to carefully push the pin halfway out of the broken link. This tool, resembling a medieval torture device, is actually easy to use. Each link has two round pins in it, attaching it to the other links. Find the broken link, and note the pin that is keeping it attached to the rest of the chain. Slowly turn your chain break tool so the poker pushes the pin out of the link about halfway. Do not push it completely through.
    • If you have a spare pin (many chainbreakers come with one), then you should feel free to use this pin, as it will be much stronger and safer to ride on.[2]
  5. Pull the broken link off the pin and discard. Keep the pin still in the rest of the chain. You only want to remove the broken link, keeping the pin in the chain. This pin will attach to the open link on the other side of the chain to put everything back together.[2]
  6. Thread the chain back onto the bike the way it came off. Before you fix the link, you need to get the chain onto the bike! Slide it through the pulley wheels they way you noted when you took the chain off. In general, the order is pretty intuitive, as there are small metal guards that hold the chain onto the gears. Simply thread the chain so that it stays between these guards and the pulley wheels.
    • To make pushing the pin in easier, turn the chain so that the exposed pin in the chain faces you, not the wheel.[1]
  7. Fit the two end of the chain into one another so the holes line up. The link with the pin in it should be on the outside, so that you can push it through all four holes (two on each link) to complete your chain.
  8. Use your chainbreak tool in reverse to push the pin through, completing the link. Before, you screwed the tool in to push the pin out of the link. Now you'll be screwing the tool in to push the link though. Work slowly, keeping your hand on the links to ensure it is all lined up.
  9. Grab the chain on each side of your newly connected links and move it from side to side to loosen up the new connection. It can also help to move the chain tool to the other side of the joint just made, and push the pin very slightly to free the two outside plates of the link from the central section, preventing binding.
  10. Lubricate your chain with bike grease. Do not use WD-40, or any other product not made for bike chains. Flip the bike over and pedal it with one hand, dropping bits of lubricant onto the chain with the other. 10-15 drops should do. Then, use a damp rag and lightly pat down the chain of any excess oil. When you run a finger on the chain it should come up slick, but not covered in a puddle of lubricant.
  11. Avoid using your biggest gear in the back gears, as the chain is now a link too short. More often than not, the bike won't even let you get into these gears, as the chain is not long enough to reach. However, the strain of trying to hit these bigger cogs will cause another break if you aren't careful.
    • Try to keep your chain straight between the front and back gears. Don't let it stretch diagonally across the gears by being all the way to the right on the front gears and all the way to the left on the back gears at the same time.
    • This chain fix is generally temporary, and you should add a new link or get a new chain shortly afterward.[2]

Adding a New Link

  1. Add a new link as soon as possible to return your chain to its normal length. If your chain breaks, you can remove the broken link and reattach the chain for a temporary fix. However, the shorter chain won't be able to fit around all of your gears, severely limiting your range. You can purchase new links, however, at any bike shop and many sport retailers
    • Master Links are made to fit easily onto any bike, anywhere. They are easy to install quickly, too, making them handy to keep in your saddle bag on long trips. They are, by far, the most common links used by home mechanics.
  2. Face the master link the right direction. Most links have an arrow on them that needs to point in the direction the chain goes when pedaling. The rest are concave (bending in) on one side, and this side needs to face towards the wheel and the rest of the bike.[3]
  3. Pinch the links together to unhook the two halves of the master link. You'll notice that the master link has a figure-eight shaped space for the pins, instead of the normal rounded pins and pin-holes for the rest of the chain. If the chain is not already unlocked, do it now.
    • Some master links come as two asymmetrical halves -- a C-shaped piece with both pins and an outside plate. To fix these chains, simply thread the C-shaped pin into the both open holes of the broken chain, then fit the plate on top.
  4. Take each half and push it through the whole on opposite ends of the chain. Each of the pins on the two halves of the master link needs to go into one of the ends of the chain. Make sure that the pins go in from opposite sides of the chain as well. You are going to hook the chain back together using the figure-eight hole, and they need to line up.
  5. Bring the chain together and link the exposed pins through the figure-eight holes on the opposing links. It's as easy as pushing the pins through the wholes. Note, however, that this connection is currently very loose.
    • Some mechanics use a tensioner, a simple C-shaped wire that hooks into the grooves of the chain, to hold it taut while linking. While not necessary, a set of hands or a similar tool to keep the chain close together makes life much easier.
  6. Use a pair of pliers to push the master link together, clicking the pins into place. You want to force the pins into the other sides of the figure-eight hole to lock them in place. If you don't have a pair of pliers handy, there is one more trick to tighten everything. Flip the bike over so it's upside-down. Holding the back break down, slowly pedal the bike. As the brake holds the wheel, and thus the chain, in place, the pressure of pedaling will pull the other side, tightening your master link.[3]
  7. Know that, in the end, a broken chain usually means you need a brand new one. While you can fix the chain in a variety of ways, as noted, a broken chain usually needs a replacement. Beyond breaking, old chains expand as the pins inside wear down. This might not sound like much in theory, but it matters when riding. The chain handles and transfers all of the force from your feet to the wheels, and a loose chain means you're doing a lot more work for a lot less speed.[4]

Tips

  • The chain breaker tool is the one tool that will pay for itself. Chains break off at times for no apparent reason. Keep it with you when biking, as it can also help another stranded cyclist.
  • Always keep an old chain or those extra links left over from a new chain replacement, as spares. Remember though that there are several types of chain made to fit specific blocks, and one may not be compatible with another.
  • Pins in the chain are specific to the number of speeds your cassette has. Ask at your local bike shop if you have any questions about this.

Warnings

  • Follow these instructions closely and carefully. Don't rush anything.
  • If you are really stuck, ask a pro
  • The pin that you pushed out should be replaced with a new pin as reusing the old pin could cause a failure. Replacement pins are available from your local bicycle shop.

Related Articles

Sources and Citations

  1. ↑ 1.0 1.1 http://thebicyclechain.com/how-to/chain-replacement-and-repair-pg80.htm
  2. ↑ 2.0 2.1 2.2 http://www.bicycling.com/maintenance/bicycle-repair/breaking-chain
  3. ↑ 3.0 3.1 http://www.artscyclery.com/learningcenter/installingandremovingmasterlinks.html
  4. ↑ http://www.bikeradar.com/us/gear/article/how-to-replace-a-chain-18117/
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