How to Fix a Mountain Bike Chain That’s Jumping Gears or Skipping
A mountain bike chain jumping between or skipping gears is one of the most common problems you may encounter when riding a bike. As this can be dangerous and can affect your overall riding experience, you should try to fix a mountain bike chain that’s jumping or skipping gears as soon as possible.
To fix a mountain bike chain that’s jumping gears, first forward pedal the bike. Next, turn the barrel adjuster, check the shifter, adjust the cable, and tighten the derailleur screw. Maintain the chain to avoid similar problems in the future.
While fixing a bike chain that is skipping or slipping gears might sound challenging, it is not that tricky at all. As long as you identify why your MTB chain is jumping gears and follow a few quick steps that will be shared in this article, you can easily fix your bike and enjoy your next ride.
What Causes Chain Skipping?
There could be plenty of reasons why your mountain bike chain is skipping gears. However, there are a few common factors that you should keep in mind to be able to fix the chain.
Chain skipping is caused by loose cables, a loose chain, a worn chain, worn cassette and chainring, incompatible parts, the shifting system malfunctioning, and too much lubricant.
This detailed guide on Biking Ultimate shares some common factors that cause a bike chain to slip or skip gears.
Below are seven common causes of mountain bike chain jumping or skipping gears.
Reason 1. Loose Cables
Cable-related mechanical issues often lead to a skipping bike chain. Cables gradually get stretched and it is essential to either adjust the tension or replace the wires from time to time with cables like these.
Cables might also get stretched if you use a low-quality shifter. As a result, the cable tension is lost during the ride, leading to random gear shifting and chain slipping. So make sure you use a high-quality shifter like this.
Reason 2. Loose Chain
If your mountain bike chain is too loose, it will probably skip or jump between gears while riding, especially at high speeds. Ideally, your bike chain should move about ½ to 1 inch in both directions for it to function properly.
You can easily solve that issue by tightening the bike chain as we discuss in our article that addresses how to tighten a mountain bike chain. You should just adjust the rear wheel in case of a single-speed bike and adjust the derailleur B screw and the rear wheel in case of a bike with a derailleur.
Similarly, be sure to read our related article explaining some easy fixes for a mountain bike chain hitting the frame or 3 simple ways to size a mountain bike chain.
Reason 3. Worn Chain
Riding your mountain bike with a worn chain could potentially cause the chain to skip gears. This is because bike chains gradually lose their shape and get damaged, making it impossible to grip onto the sprocket teeth.
Depending on your riding style, it is recommended to replace your bike chain every 2,000 to 3,000 miles with a chain like this. This will not only prevent the chain from skipping gears but also prolong the life of the drivetrain.
Reason 4. Worn Cassette and Chainring
Having a worn cassette or chainring on a mountain bike is yet another common cause of a bike chain skipping gears. While the cassette and chainrings also wear down, riding with a worn chain accelerates the process.
When a bike chain is damaged or stretched, it widens the gaps between the cog teeth. And even if you replace the chain, it may keep skipping gears as the cassette and the chainring have been damaged as well, in which case you will have to replace them with a new cassette like this and a chainring like this.
Reason 5. Incompatible Parts
There is nothing worse than riding a mountain bike equipped with drivetrain parts that are not compatible with each other. Along with being pretty dangerous, incompatible parts often damage each other due to size or function differences.
If a bike chain is not suitable for your specific bike cassette or the chainring, it may start skipping gears. Therefore, you should always pick new drivetrain parts while following the manufacturer’s recommendations or buy a kit like this.
Reason 6. Shifting System Malfunction
If any of the shifting system components malfunction, your mountain bike chain might start skipping gears. The rear derailleur being unaligned and the derailleur hanger being damaged after a crash are two of the common shifting system problems. These factors significantly affect shifting performance and can lead to a chain slipping over gears.
Reason 7. Excess Lubricant
Last but not least, lubricating your mountain bike chain with too much lube like this can lead to jumping between or skipping gears. This is because too much lube makes the chain more slippery and prevents it from smoothly rotating across the sprocket teeth. As a result, the chain may slip over the cassette or the chainring. For more detailed information, be sure to read our related article explaining how to lube a mountain bike chain properly.
You might also find interest in learning some quick steps to clean a mountain bike chain properly or our step-by-step guide explaining how to clean mountain bike gears. Be sure to read our related articles to find out more.
Effects of a Bike Chain Jumping Between Gears
Undoubtedly, a bike chain slipping over the cassette or jumping between the gears affects your overall riding experience. But what are the most common effects of a skipping bike chain?
The most common effects of a bike chain jumping between gears are the bike chain slipping in one gear, slipping on the cassette, and the rear derailleur slipping under load.
Below are a few ways your bike chain might be jumping between gears and how they affect your riding.
Effect 1. Bike Chain Slipping into One Gear
A damaged, rusty, or dirty cassette can cause your bike chain to slip in the same gear repeatedly. While you can easily clean your dirty cassette, you may need to replace a rusty or uneven one with one like this for it to function properly.
When the cog teeth are either rusty or uneven, the bike chain can no longer grip onto the teeth and rotate smoothly. Therefore, it slips into the gear that has been damaged.
Effect 2. Bike Chain Slipping on Cassette
When a bike chain, especially a new one like this, slips on the cassette, the problem is most likely related to the cassette. This is because the cassette has already been worn down while the bike chain has less apparent wear.
To prevent a bike chain from slipping on a cassette, it is recommended to replace the drivetrain parts simultaneously with a kit like this. Ideally, you should also switch your bike cassette when replacing the bike chain and vice versa.
Effect 3. Rear Derailleur Slipping Under Load
If your rear derailleur is slipping under load, you should first check the cables. When replacing them with cables like these, they stretch during the first couple of rides and it is completely normal. You should just tighten the cables up to keep the derailleur from slipping under load.
If your cables are pretty tight but the rear derailleur keeps slipping under load, you should consider checking the derailleur hanger. If it is not aligned properly, use a derailleur hanger alignment tool like this to easily adjust it.
Finally, ensure that your derailleur limit screws are tightened. If not, adjust them to prevent the rear derailleur from slipping.
Effect 4. Bike Chain Skipping When Pedaling Hard
If your bike chain skips when pedaling hard, you are probably dealing with a loose chain. When a bike chain is not tight enough, it can easily fall off the sprockets, causing it to skip gears. You can easily fix this by tightening your bike chain.
Another reason your bike chain jumps between gears when pedaling hard is that it needs to be lubricated properly. Check the chain, clean it, and grease it with the right amount of lubricant. Check out our article about proper mountain bike chain maintenance to find out more about how to lubricate the chain.
Materials Needed To Fix a Mountain Bike Chain That’s Jumping Gears
As long as you have the right materials and tools, you can easily fix your mountain bike chain that is skipping gears.
Materials needed to fix a mountain bike chain that’s jumping gears are a screwdriver, rag, chain lubricant, and calipers or a ruler.
We provide the ultimate list of tools needed for mountain bike maintenance so that you can have all the tools needed to work on your bike. Below we list the tools needed to fix a bike chain that jumps between gears.
Tool 1. A Screwdriver
A screwdriver from a set like this is a crucial tool that you will need when fixing a bike chain that jumps between gears. You will actively use it when loosening or tightening screws while adjusting the derailleur.
Tool 2. Allen Keys
Allen wrenches like these, or hex keys, come in handy when adjusting bolts. You will need them to loosen or secure the thru-axle when tightening the bike chain to prevent it from skipping.
Tool 3. A Rag
When fixing a bike chain, you should always have clean rags like these to wipe away grease and keep yourself clean.
Tool 4. Chain Lubricant
Lubricating your bike chain with lube like this is essential for repairing or maintaining it. When fixing a bike chain that jumps between gears, you will most likely need some chain lubricant to lube it properly.
Tool 5. Bike Chain Cleaning Kit
If your bike chain needs lubrication, you should first properly clean it with a kit like this to prevent dirt from accumulating and clogging the tiny spaces inside the chain links. A chain cleaning tool is a perfect device for thoroughly cleaning your bike chain in just a few minutes.
Tool 6. Calipers or a Ruler
To determine how loose a bike chain is, you will need a ruler or calipers like this that will allow you to measure the chain stretch.
Tool 7. Derailleur Alignment Tool
If your bike chain is skipping due to your rear derailleur hanger being bent, you will need to use a derailleur alignment tool like this to align the hanger and fix the skipping chain.
| Tool | Function | Example from Amazon |
| Screwdriver | Tighten derailleur | Workpro Ratcheting Multi-Bit Screwdriver Set |
| Allen Keys | Loosen or tighten bolts | Amazon Basics Hex Key Set |
| Rag | Wipe away grease | Mr. Siga Microfiber Cleaning Cloth |
| Chain Lubricant | Lubricate bike chain | Wd-40 Specialist Bike Chain Lube |
| Chain Cleaning Kit | Remove grease and dirt from the chain | Park Tool Cg-2.4 Bicycle Chain and Drivetrain Cleaning Kit |
| Calipers or Ruler | Measure chain stretch | Kmc Digital Chain-Checker |
| A Derailleur Alignment Tool | Align a bent derailleur. | Park Tool Dag-2.2 Derailleur Hanger Alignment Gauge |
How to Fix a Skipping Bike Chain
Having a bike chain that skips gears can be a total nightmare. However, you can easily fix the problem as long as you get the right tools and follow the steps.
To fix a skipping bike chain, first forward pedal the bike. Next, turn the barrel adjuster, check the shifter, adjust the cable, and tighten the derailleur screw.
Below are nine quick and easy steps to follow to fix a bike chain that jumps between gears.
Step 1. Move the Bike Pedal Forward
To fix a skipping bike chain, you should first manually forward pedal the bike and shift the chain from the smallest cog into the biggest cog on the back and the biggest chainring on the front. This will allow you to observe how loose or tight the bike chain is and whether you need to adjust its tension.
Step 2. Turn the Barrel Adjuster
Barrel adjusters look like serrated knobs and are often considered solutions to cable tension. Barrel adjusters ensure that the derailleur’s guide pulley lines up with the cogs and each shift is aligned with each cog. To solve the shifting problem, you turn the barrel clockwise in half-turn increments.
This YouTube video tutorial by Park Tool explains how barrel adjusters impact shifting.
Step 3. Check the Shifter
The next step is to check the shifter by pressing it once. If the chain shifts to the smallest cog of the cassette, it is tight enough. If not, then you need more tension in the chain.
Besides that, checking the shifter will allow you to determine if the chain moves up a gear. If it does nothing, you will need to re-adjust the barrel adjuster so that it shifts properly. For more information about this check out our article that explains how to fix mountain bike grip shifters.
Step 4. Adjust the Cable
As mentioned earlier, loose cables can cause the bike chain to jump between gears. To fix a skipping bike chain, you should just add tension to the stretched rear derailleur cable.
To adjust the rear derailleur cable tension, you should first shift your bike to the smallest gear to release chain tension. When the cable becomes loose enough, use an Allen wrench to remove the bolt holding the cable. Then, pull the slack with your hand to tighten the cable and secure the bolt.
For detailed instructions on how to adjust the rear derailleur cable tension, check this YouTube video tutorial by Brad Buccambuso.
Step 5. Tighten the Derailleur Screw
When fixing a jumping bike chain, you might need to tighten the chain by simply adjusting the derailleur body-angle screw, also referred to as a B screw. To do so, you should use a screwdriver and tighten the derailleur screw so that you add tension to the bike chain and prevent it from skipping and slipping.
Step 6. Align the Derailleur Hanger
Since the derailleur hanger protects your bike frame and other drivetrain components in case of a crash or other accidents, it can be broken or bent pretty easily. Whenever the derailleur hanger is damaged, there is a risk that your bike chain will start jumping between gears. To prevent this from happening, you should use a derailleur hanger alignment gauge and align the derailleur hanger both horizontally and vertically.
This YouTube video by Park Tool demonstrates how to properly use a derailleur hanger alignment gauge.
Step 7. Measure Chain Wear and Replace the Chain if Needed
Having a worn chain on your mountain bike could be the reason the chain keeps skipping gears. To check if your bike chain needs to be replaced, you should measure chain wear using a chain wear indicator tool like this. You can use a caliper or a ruler as an alternative.
This article by Park Tool discusses a few methods to check chain wear.
If your bike chain is too worn down, consider replacing it with a new one that will sit tighter. This will not only prevent the chain from jumping or slipping but also minimize the risks of damaging other drivetrain components.
Step 8. Check if the Cassette is Worn Down
Riding a mountain bike with a worn cassette is a common reason a bike chain jumps between gears. Oftentimes, smaller cogs are worn down more than larger cogs, so you should always pay attention to the smaller ones. If you notice that the cog teeth are damaged or uneven, you should consider replacing the cassette with one like this to fix the skipping bike chain.
Step 9. Clean and Lubricate the Bike Chain
Oftentimes, the bike chain jumps between gears because it is not lubricated properly. If this is the case, you should first clean the chain using a bike chain degreaser and a chain cleaning device from a kit like this. Next, you add about one drop of lubricant to each link of the chain to properly lubricate it. For more information on lubrication alternatives check out our article.
Here is a quick YouTube video tutorial by Trek Bicycle on how to clean and lube your bike chain.
At some point, you must be wondering if you're better off replacing your chain instead. Before you go any further, be sure to check out our related article explaining how much is a mountain bike chain with price comparison charts for more details.
What Gear Should My Bike be in to Prevent the Chain From Jumping Gears?
Since the most common culprit of a skipping bike chain is a loose chain, tightening it allows you to easily solve the issue. But what gear should the bike be on to keep the chain from jumping between gears?
A bike should be in the lowest gear to prevent gear jumping.
When shifting your mountain bike to the lowest gear, the chain is on the largest cog on the rear derailleur. Therefore, having your bike on the lowest gear keeps your bike chain tight, preventing it from slipping over the cogs or skipping gears.