Why is my bike chain skipping under load? [Reasons & Fix]

Ouch!

It could hurt my groin.

I have been using my new roadie for a couple of weeks. Yesterday I was riding it in my local area.

All of a sudden, the bike stopped, and I fell from the saddle. Fortunately, I didn’t fall on the frame. Otherwise, I could get injured on my groin.

However, I get off the bike to see what happened. What I noticed is the chain was stuck between two cassettes of the rear derailleur.

Thank God I manage to control my body balance. Otherwise, something unpleasant could happen.

Anyways, the phenomenon happens because of the skipping chain. Sometimes, the chain skips cog teeth while riding. As a result, chain stuck or falls occur.

Why is my bike chain skipping under load?

It can happen because the rear cassettes or chainrings are aligned wrong.

Besides, the chain can get stretched; that’s why skipping the cog teeth.

However, the chain or derailleurs themselves can be the culprit when they are damaged severely.

Let’s discuss all these possible reasons and find out the solution.

1. Misalignment of Derailleurs: This is what happened in my case. It was a new bike. So there was no sign of a damaged drivetrain.

But, the hanger was bent somehow. That’s why the rear derailleur misaligned and caused chain skip.

2. Stretched Chain: The chain skip can occur because of the stretched chain.

When the chain is elongated and gets longer than the required chain length, the chain tension decrease. Thus, the chain skips while paddling hard.

3. Damaged Drivetrain: It’s one of the most common reasons for chain skipping. When the chain gets two rusty or worn, it can’t stay on the cog teeth.

On the other hand, chain skips when there are broken teeth on cogs or chainrings.

4. Wrong Chain: There are various types of chains for different kinds of bikes. The chain for the Shimano groupset is different from the chain for SRAM.

If the chain you use is not compatible with the bike’s derailleurs, it can skip.

5. Problem on the Freewheel: The freewheel or ratchet mechanism of a bike allows to keep the bike running when not paddling.

The rear wheel rotates when you paddle clockwise. But when you don’t paddle, the freewheel prevents the bike from stopping.

Sometimes, the freewheel is damaged inside. As a result, the hub fails to transfer energy through the wheel. Thus, an artificial chain skip appears.

Anyways, one or more problems from above can appear on your bike.

Try to solve these problems by following the below instruction or take help from a professional mechanic.

A quick fix of chain skipping under load

Now, you’re probably thinking, how should I fix all these problems.

Have a relax and let’s know it in short first.

Well, to get rid of chain skipping, you have to fine-tune your bike first. Adjust the derailleur and ensure the correct alignment of the chain.

If the chain is too loose, you have to reduce one or two chain links from it. After that, check the entire drivetrain.

Is it too rusty or worn out? Replace the chain or derailers as necessary. In the end, take some preventive steps so that, skipping chain can’t appear again.

How to stop chain skipping under load?

These three tips below can help you to eliminate chain skipping problems.

Tip-1: Adjust the Derailleurs

Most commonly, misalignment in a derailleur is caused by the limit screws’ position or cable tension.

But sometimes, it can happen for derailleur hanger bent. A derailleur hanger is a small piece of metal that holds the rear derailleur down the cogset.

Limit screw or barrel adjustment won’t work if the hanger is bent. So, it’s better to adjust the hanger first.

Then, hang the bike on a Repair Stand, and let’s fix it.

1. You can fix a bent hanger with your bare hand. Pull and push until it seems in an ideal position.

But for getting an accurate alignment, you will need a tool called DAG-3 Hanger Alignment Gauge.

It can diagnose and fix bent derailleur hangers.

2. Remove the rear derailleur with an Alen Key. Then, thread the gauge on the hanger hole.

If it seems difficult to thread the gauge, clean the hole with alcohol. And then mount the gauge.

3. Now, turn the gauge to the 3‘O clock position. Rotate the wheel and bring the tire valve parallel to the sliding indicator.

We will take the valve as a constant to adjust the hanger from different positions.

Eliminate the indicator and wheel rim gap by adjusting the indicator pin, then lock the slider.

4. Then, turn the gauge to the 9 o clock position. Rotate the wheel to bring the valve in line with the indicator Check if the gap between the rim and indicator is less than 3 mm.

If the gap is bigger than 3 mm, push the gauge to ensure the required distance.

5. If the gap is too smaller than 3mm, get back to the 3’ O clock position and measure the gap.

Adjust if it is not around 3 mm. Repeat the above steps until the indicator acquires a 3 mm gap for both 3’ O clock and 9’ O clock positions.

6. Horizontal alignment is set. Now, let’s focus on the vertical alignment. Bring the indicator to a 6’O clock position and measure the gap.

Is it less than 3 mm? If it’s not, set the indicator to the rim and go to the 12‘O clock position.

Now, push the gauge to bent the hanger and ensure a 3 mm gap. 

7. Now, get back to the 6 clock position and check the distance. If it’s not around 3 mm, bring the gauge to the 9’ O clock position. Bend the hanger to ensure a 3 mm gap.

Repeat the process until the hanger acquires 3mm distance at 6’ O clock, 9’ O clock, and 12’ O clock positions.

8. Lastly, unmount the gauge and reinstall the derailleur. Don’t forget to recheck the derailleur adjustment.

I have described it in one of my previous posts so, I won’t repeat it.

Read Also: Rear derailleur adjustment.

Note: In extreme cases, the hanger can break while bending. So it’s better to get a Spare Hanger for safety. However, take your time to conduct deep research to get a suitable spare hanger for your bike.

Tip-2- Adjust Chain Length or Tension

Sometimes while installing a new chain, the mechanic can put on a longer chain than the requirement.

As a result, the chain skip. However, you have to reduce the chain length to get ideal tension.

For that, you can delete a link from the chain. Let’s do it.

1. Rotate the bike backward and search for the master link. It looks slightly different from other links.

If your bike features a master link, it’s easy to break the chain with a Master Link Pliers.

Otherwise, take a Chain Tool and break the chain wherever you want.

2. For breaking the chain, set the chain link to the chain tool and slowly tighten the bolt.

Do it until the pin is near to come out. Make sure the pin doesn’t come out totally.

3. Now, remove one or more link(s) as required. Again use the chain tool to remove the link.

Finally, close the chain with the tool. Closing the chain is almost the same as the opening.

Just to place the chain outward to the tool.

Tip-3-Replace Chain or Cassettes

The cassettes and the chain can get damaged over time. Besides, the bike chain wears out after a certain period.

When you paddle with damaged cassettes or a worn chain, the links roll over the cog teeth, and it skips.

If your bike has broken derailleur teeth or a worn chain, it’s better to replace them instead of fixing them.

1. To identify a worn chain or damaged cogs, you will need a few tools like the Chain Checker and the Sprocket Checker.

2. Let’s check the chain first. At first, take the chain checker and look at which side is marked with 0.5.

Insert the tool’s head in a link and try to insert the 0.5 marked tail in the chain.

If the tail can’t penetrate easily, your chain is not worn more than 0.5%.

3. If the 0.5 marked tail can easily insert into the chain, try to insert the 0.75 marked tail.

If the 0.75 tail can also penetrate smoothly, then your chain is 0.75 % worn.

But what does it mean? Well, you must replace the chain with 0.75% wear.

Other hand, you can use the 0.5% worn chain for a few rides. But, I suggest replacing it too.

4. Now, let’s check the cassettes with a sprocket checker. Take the checker and put’s its chain-like part on the cogs.

Then, apply a rotational force on the handle. Now, try to pull up the chain from the opening link.

Do you feel any resistance? If the answer is no then, the derailleur is in good condition. Otherwise, it is worn and needs a replacement.

5. To replace the chain and derailleur, you need a chain breaker tool, Adjustable Wrench, and Lock Ring Removal Tools.

I have described earlier how to break and close a chain. Now, let’s know how to replace the cassettes.

6. After removing the derailleur, loosen the quick release and take out the wheel. Use a compatible lockring remover tool and loosen the lockring.

The cassettes are removed. Now reinstall the new cassettes as you remove the old ones.

However, don’t forget to lube them before installing them.

Freaky Tip: If you want to increase the durability of your drivetrain, then keep the chain clean and lubricated. Read our Bike Chain Cleaning & Maintenance guide.

Frequently Asked Questions About Bike Chain

Conclusion

Skipping chain is not just a threat to bicycle safety. It’s a threat to the shifting power and the overall performance of the bike.

It’s disappointing if you can’t get the expected gear ratio when on the bike. Besides, frequent chain falls can stop your ride again and again. It will be annoying, won’t it?

Follow these three simple tips I have described above and get rid of the chain skipping problem.

By this, you can save your bike from a torn chain or broken teeth.

In return, you will get enhanced safety and an excellent performance from your bike. It will be fun and more enjoyable then.

I hope you will enjoy your next ride.

Cheers!