Why Motorcycle Chain Becomes Loose?

Motorcycle chain with back wheel

Despite all the tightening and adjustments you have made, the motorcycle chain has become slack again, is it? Your motorcycle chain becomes loose again and again.

Sometimes, the chain is so much loosened that it can practically hit the swing arm.

This situation can apply not just for an old worn-out chain but can also appear in a new chain and sprocket.

Here’s why your motorcycle chain becomes loose. The chain and sprockets are worn-out and damaged. A new chain can also become loose if your rear axle is stripped and cannot be tightened enough or a spacer is missing. Sometimes, rust on the chain can cause the loosening too.

Let us look into the reasons one by one.

Reasons for the Motorcycle Chain to become Loose

#1 Worn-out Chain and Sprocket

A worn-out or a damaged chain sprocket can cause your chain to become loose frequently. Even if you tighten them, they will loosen up from time to time.

So, how to check whether the chain sprocket has worn-out?

Fortunately, checking chain drive components for wear and damage is easy since it can be inspected visually.

All you need to do is pull the chain away from the rear end of the sprocket from the rear wheel. Now examine the pulled sprocket for any wear and tear. Usually, if the sprocket is worn-out you will see about half a tooth of the sprocket. A good conditioned chain will wrap around the sprocket tightly and will not be easy to pull away.

Repeat the above exercise for a few more sprocket at various parts of the chain. Kind of like a sampling study. If you see worn-out sprockets most of the times, it is time for you to replace your old chain with a new one.

#2 Rust in the Chain

Just like checking for the wear in your chain, you also need to check for rust. A rusty chain and sprocket are also a cause for a loosened chain in your motorcycle.

So, how to check for rust then?

It is similar to how you check for wear and damage in the chain. Spin the rear wheel to see whether the chain sprockets maintain the same amount of tension throughout the time. You need to examine for the entire length of the chain to check for any signs of rust and damage.

If you find any of the teeth is chipped away or filled with rust, then again it is time for replacement of your old chain with a new one.

#3 Rear axle is Stripped

This is the most common cause for your motorcycle chain to become loose.

This likely situation can be easily checked and if found to be culprit, can also be easily repaired. All you need to do is inspect the threads on both the axle nut and the threads on the axle to see whether they are mangled or rounded off.

Another way to assess the problem is to see whether the stripping is happening by checking the tension in the chain when tightening. If the chain reaches a maximum tightening point and never gets harder, then it surely looks like your rear axle is stripped.

Effects of a Loose Chain

Now, let us look into the effects of a loose chain on your motorcycle.

Firstly, a loose chain will create jarring noises whenever the chain runs over the sprockets. Eventually, this might lead to the chain getting out of the sprocket, which in turn might prove dangerous for the rider.

Next, a loose chain will also result in loosening the rollers on the inside of the chain. Furthermore, the rings might get worn-out and get damaged quickly if left unchecked for a long time.

So, it is imperative for you to keep the chain in precise tension and diagnose the motorcycle if you have a loose chain.


Since we now know the cause and effect scenario, let us look into the remedy.

If the chain is loosening because of rust or because the sprockets have worn-out, then the solution is to replace the motorcycle chain with a new one.

If you are aware of the process of replacing an old chain with a new one, then you can easily do it yourself. Else, you can dial up your mechanic for the replacement.

However, if it is the new chain that is causing problems, you need to check whether the rear axle is stripped. And if it turns out, the rear axle is stripped, you need to take your motorcycle to your mechanic. The solution here varies from adjusting the slack and tightening the nuts to even replacing your rear axle.

Preventive Measures

So, how to prevent getting your motorcycle chain loosening?

Well, you need to properly clean, lubricate regularly and adjust the chain tension for every 5000 kilometres you ride in your motorcycle. This frequent diagnosing will make your chain to run smoothly and last longer without getting loosened up.