Top Reasons For a Loose Motorcycle Chain & How To Fix It

A motorcycle chain is one of the most important components of a motorcycle. It connects the engine to the rear wheel and forces it to spin, allowing the motorcycle to move forward. Without one, a chain-driven motorcycle will obviously not move very far! 

A loose chain can cause a variety of problems and even damage to the motorcycle and possibly the rider too. In a worse-case scenario, the chain might come off the motorcycle's sprocket completely whilst the bike is in motion, and potentially cause an accident.

There are a number of reasons why a motorcycle chain may loosen over time and potentially cause issues for you and your bike. Here are a few of those reasons.

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1. Chain Wear

A worn-down chain is a possible reason why it is becoming looser over time; as the chain is used more and more, the links start to stretch and loosen causing more play, or movement up and down, on the chain. This movement might only be minimal, but applying this movement to every link on the chain means that there can be a noticeable difference over time.

Your motorcycle chain should be replaced at least in accordance with the manufacturers guidelines for your motorbike, or when a qualified technician suggests doing so as part of your bikes regular servicing.

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2. Tensioning Bolts Need Tightening

If your chain is relatively new and still loose, the cause may be the tensioning bolts. In many cases of a loose chain, these bolts are the cause. They are located at the back of the swingarm where the wheel is attached and can be adjusted to move the rear wheel closer or further away from the engine, thereby tightening or loosening the chain depending on how it is moved.

They are relatively easy to adjust; simply lift the rear tyre off the ground and support the bike, preferably with a paddock stand, and loosen the rear spindle and tensioning bolts to tighten the chain in this manner. Do not completely remove these items; just loosen them until the rear wheel is able to slide forward and backwards.

From here, move the rear wheel back until there is enough space for the chain to be tight, with around an inch of play up and down. The chain must be slack enough to move freely when the gears are changed, but not slack enough that it can come off the sprocket. Additionally, the chain mustn't be too tight, as this can cause extra strain and wear on the sprockets and potentially cause it to snap.

Once set to a position you are happy with, re-tighten the bolts and spindle to the correct torque settings. If you're unsure or not confident in your ability to perform this task, don't even try. Take your bike to a proper motorcycle mechanic to get the work done.

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3. Worn Down Gear Teeth

If the teeth on the front or rear sprockets are worn down, the chain may start to become more loose as there is a smaller tooth going between the links on the chain, spreading them out less as they move around the sprocket. This can give the appearance of a loose chain, so it is a good idea to check the wear of the sprockets regularly. Worn sprocket teeth look thinner and pointier, rather than fatter and rounder, and may also be chipped or show different signs of wear. Get some help if you're unsure whether you need a new sprocket or not.

Dangers Of A Loose Chain

When a chain isn't adjusted properly, it can affect the way a motorcycle works in many ways, particularly when stopping, turning, and speeding up. When changing gears, a slack chain may jump on the sprockets, resulting in a loss of power and possibly causing the rear wheel to jam if the chain becomes stuck between the swingarm and the sprocket. This could result in an accident as the rear tyre may lock up.

A loose chain could also break if it is worn enough; this can have catastrophic effects, the first of which is that the motorcycle will lose all power as there is nothing driving the rear wheel and enabling it to turn, therefore causing the rider to take immediate action with no way of powering themselves forwards out of danger, simply relying on momentum.

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A broken chain can also wrap around the back wheel of a motorcycle causing it to lock up and skid down the road. The chain could also fire out the back of the motorcycle like a missile, potentially hitting a motorist or car, or whip your leg or foot, possibly causing major damage if protective gear isn't being worn.

How To Prevent Loose Chains

The best way to prevent a loose motorcycle chain is to perform regular maintenance on your bike; which includes cleaning the chain, adding the relevant lubrication, and checking and, if necessary, adjusting your chain at regular intervals to ensure it is not too slack or too tight. Regular servicing of your motorbike by a qualified technician in accordance with the manufacturer's guidelines is one of the best ways to ensure your bike and you remain as safe as possible out on UK roads.

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