If your chain is slack or keeps dropping off your bike, you’ll want to learn how to tighten a bike chain.
Slack chains are a common issue for cyclists, but they’re fortunately relatively easy to fix. You can diagnose and solve the issue within minutes with a few simple tools and some patience
Even if it takes a few tries, it can save you the time and energy involved in visiting a bike shop.
Here we cover how to tighten a chain on a single-gear bike and one with a derailleur in just a few simple steps.
Table of contents
What tools do you need to tighten a bike chain?
To tighten your bike chain, you’ll need the following:
- the bike stand
- a socket wrench
- an allen key
- bike chain lubricant
- an old rag or cloth
- some gloves to protect your hands
A quality bike repair kit should include most of the above—it’s good for cyclists to have to hand.
How to tighten a bike chain on a single-gear bike
Single-gear or ‘single-speed’ bikes have a fixed cog in the rear hub rather than a freewheel mechanism. Your legs are essentially your gears on this kind of bike.
It’s pretty straightforward to tighten a chain on a single-gear bike, provided you take your time to get the tension right.
1. Place your bike on its stand
Turn the bike upside down by placing it in its stand. This allows easy access to the parts and makes the process much easier.
If you don’t have a bike stand, place it on a flat surface where it’s unlikely to get damaged—it’s a good idea to cushion the saddle with a mat.
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2. Loosen the rear axle
Using the socket wrench, remove each of the axle nuts holding the tire in place. Do so by twisting them anti-clockwise until they come loose.
3. Pull the rear wheel backwards
Carefully pull the rear tire backwards to tighten the chain. Do this slowly and gently, as rushing the process could cause the ain to snap.
Keep checking the chain’s tightness as you pull on the tire and stop once the chain can only move around half an inch in either direction.
Try to keep the tire inside the bike’s wishbone to make reassembling the wheel easier.
4. Re-tighten the rear tire
Once you’re happy with the result and the chain has optimal tension, you need to fix the rear axle back into place.
With the socket wrench, carefully screw each of the nuts back into position using a clockwise motion until the tire is secured.
It shouldn’t touch the bike frame or chain—if it does, you need to loosen it up and try again.
5. Test your chain
Give the wheels a spin to check everything is in order. The chain and pedals should rotate easily, and the rear tire shouldn’t make any contact with the frame or chain as it spins.
Move the chain with your fingers, and ensure it only moves up or down around half an inch.
If there are any issues, you need to loosen and pull back the rear tire and repeat the process.
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How to tighten a bike chain with a derailleur (step-by-step)
Bikes with derailleurs benefit from an advanced gear system. They make pedaling easier, especially when you’re cycling uphill.
However, due to the gear-shifting mechanism, there’s more involved in locating the cause behind a loose chain.
There’s also a greater risk of your foot getting caught in the chain, which can cause a nasty injury. If you have a loose chain on a bike with a derailleur, it’s something you should fix as soon as possible.
You may want to take it to a professional at a bike shop, but we’ve covered the process in five simple steps below if you want to try it.
1. Place your bike on its stand
As you would when inspecting a single-gear bike, secure the bike in its stand with the saddle facing the ground.
If you don’t have a bike stand, place it on a flat surface where it’s unlikely to get damaged. You might want to cushion the saddle with a mat.
2. Locate the rear derailleur screw
Multi-gear bikes have a screw located behind the derailleur. This is often referred to as the B-tension screw, and you can find it by looking for the letter ‘B’ written adjacent to it.
It aims to alter the distance between the top pulley and the freewheel or cassette, changing chain tension.
Carefully turn the screw in a clockwise motion to tighten the chain. If this works, you can skip to step five and test your bike.
3. Check the condition of the chain
If the above step didn’t increase chain tension, then it could be that the chain itself is in poor condition.
To test this, use a chain checker to measure the chain and determine whether general wear and tear is the reason behind the slackness. Watch the video below for a complete walk-through of this process:
You’ll need to replace the chain if it’s slack and potentially the sprocket if this is also worn. Attaching a new chain to a worn-out sprocket will only cause more problems.
4. Use the rear wheel to adjust chain tension
Since multi-gear bikes have rear brakes, you need to disconnect them from the brake cable and lift the lever or quick-release lever before you can access the rear wheel.
Once you’ve done this, carefully pull the rear axle back towards the rear dropouts to tighten the chain.
Keep making small adjustments by moving the axle, lowering the quick-release lever, and checking the tension before repeating the process until the chain is tight.
When you’re satisfied with the chain tension, reconnect the brakes to the cable and secure them with the quick-release lever. Check the tires are a good distance from the chain and bike frame.
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5. Test your chain
Before getting back on your bike, rotate the wheels and pedals to check the movement of the chain.
Everything should rotate easily, and there shouldn’t be any contact between the tire and the bike frame or chain.
Move the chain with your fingers, and ensure it only moves up or down around half an inch. If it does, you’ve successfully learned how to tighten a bike chain!
If this process doesn’t work, either retrace your steps or seek help from a professional at your local bike shop.
Understanding your bike can make maintenance much easier. You don’t have to know all the ins and outs, but just learning the basics behind how each component works can make all the difference.
We’ve put together some FAQs to help you diagnose minor problems with your bike chain and take the necessary action.
1. How does a bike chain work?
This is a common question among those wishing to learn how to tighten a bike chain.
In short, a bike chain transfers power from the pedals to the drive-wheel, which propels your bike forward.
It’s made up of multiple wide and narrow links connected by rivets. Each outer link has a roller, whi meets the chainrings and cassette on the drivetrain and allows the chain to move smoothly around it.
2. Why do bike chains become loose?
There are a few common reasons behind a chain becoming loose:
- general wear and tear
- placing a new chain on old components
- a weak derailleur spring
- the rear axle is positioned too far forward in the rear dropout
Sometimes it isn’t easy to spot a loosening chain when it’s in the early stages. If you’re unsure whether your chain is loose, here are some common symptoms:
- bike chain making contact with the frame
- bike chain dropping or skipping
- rapid drivetrain wear
- poor shifting
Knowing the causes and indicators of a loose bike chain will help you diagnose and fix the issue before it becomes more of a problem.
3. How tight should a bike chain be?
At optimal tightness, a bike chain will allow you to move it up or down around half an inch. If it appears slack or looser than this, then it needs to be adjusted to the right tension.
4. How often should I lubricate my bike chain?
To get the most out of your chain, it’s a good idea to lubricate it at least once every 100 miles or once per week if you’re riding on most days.
It’s an important step in your regular bike maintenance routine. If you ever don’t have time to properly clean and lube your chain, make sure you at least wipe it down with a clean rag.
Related: How to clean a bike chain
5. How do I decide whether to replace or tighten my bike chain?
If your chain is loose because it’s rusted or worn, then you should replace it. This is especially true on bikes with derailleurs, as a worn chain can affect the lifespan of other components.
If it’s relatively new but has become worn, you may need to replace it this time before committing to regular bike maintenance to prevent this from happening in the future.
Chains wear down much quicker when they aren’t regularly cleaned and lubricated.
Got a loose chain that is new and well-maintained? Then simply tightening it should do the trick.
Specialist cycling insurance from Cycleplan
Now you know how to tighten a bike chain, you can prevent unnecessary costs in fixing or replacing it. You may also want to prevent this through specialist cycling insurance.
With Cycleplan, the cover protects your bike on a new for old replacement basis. If it’s stolen, bought new and is less than three years old, we’ll replace it with a brand-new bike. We can also help cover the cost of repairs if it’s damaged.
Each policy comes with the Ripe Guarantee—if you take out a policy and find the same cover elsewhere for less than 14 days, we’ll refund the difference.
Learn more about how we can help here, or get an instant online quote today.