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If you are so concerned about why does the chain keep slipping off your mountain bike, you are not alone.
Mountain bikers often face this problem, and the reason could be more than one.
Common causes for chain slippage for example can be, a malfunctioning chain, rear/front chain cassette, or the derailleurs.
It is essential to understand what causes the issue of chain slippage to ensure a comfortable bike ride.
Let’s get into it!
8 Reasons Why The Chain Keep Slipping Off A Mountain Bike
1. Check The Sprockets For Dirt
Sprockets are wheels with teeth-like structures, which are sturdy, and lock onto the chain.
When there is a lot of dirt and grime accumulated on the sprockets, it could lead to the slipping of the chain.
The oil and dirt combination could lead to the forming of a black mixture on the sprockets.
It is recommended to clean up the sprockets once in a while to avoid slipping off of the chains.
2. Worn Out Chain
A worn-out chain would easily slip off the cassette or the front chainrings.
If your mountain bike has undergone high-intensity pedaling, then you know why your chain has worn out easily.
There are chances that the rollers have lost their standard round shape, and the plates have elongated too, due to the high-intensity riding.
The tool called chain ruler would be worth investing in, in order to check the chain’s condition regularly.
Pay close attention to the wearing of the chain, and follow one useful tip, replace the chain as soon as possible as it will prevent damaging both the cassette and chainrings.
3. Worn Cog Teeth
When you inspect whether the chain has worn out, you should also check the condition of your bike’s cog teeth.
A worn-out cog teeth can also lead to the slipping off of your mountain bike’s chain.
This could be a counter-effect of the stretched chain that comes continuously in contact with the cog teeth.
4. Incompatible Drivetrain Parts
Sometimes, mountain bikers make the mistake of replacing the chain or cassette without checking the drivetrain compatibility.
Drivetrain parts must be picked up referring to the manufacturer’s recommendations.
You might end up with a slipping chain or persistent cracking noises while pedaling if you have the wrong drivetrain parts on your mountain bike.
5. Excessive Lubrication
Some people have a misconception that too much lube will improve the efficiency of pedaling.
The truth is, a small amount of lube is sufficient for impressive pedaling, and excess of it can lead to the chain slipping.
The slipping off could be worse if the chain has stretched.
This is because the presence of excess lube could result in losing the required contact between the sprocket’s teeth and the chain.
6. Disoriented Shifting Setup
A wrong shifting setup can result in the chain slipping off your mountain bike or it jumping from cog to cog.
A bad setup could also lead to cracking sounds while riding the bike.
Inspecting the shifting cable, rear derailleur, derailleur hanger, and the shifter is recommended to ensure that the shifting setup is accurate.
The shifting cable is prone to stretching after prolonged use and hence may require tension adjustment or complete replacement.
The alignment of the rear derailleur must be checked, as it is quite prone for misalignments to happen after some use.
Since the derailleur hangers are a fragile component, which could bend due to hard contacts, they are capable of causing chain jumps.
If the quality of the shifter is low, it could lead to the inefficient working of the cable due to decreased tension.
When you are riding out of the saddle, it could lead to unwanted shifting of gears, which may give you a chain slipping-like experience.
7. Bent/Damaged Derailleur Pulley Cage
A derailleur pulley cage that is damaged or bent would give the same experience as a pulley cage with undesirable alignment.
To understand whether the derailleur is misaligned, you can make a visual inspection of the rear wheel.
Looking head-on will help in analyzing whether the derailleur is capable of preventing the chain from slipping.
Next, check if the derailleur is damaged by going up or down in gears.
If there is any damage, you may want to inspect the cable, starting from the front derailleur shifter and moving on to the derailleur.
Turn the adjuster placed near the attachment of the cable clockwise and counterclockwise to adjust.
See if you are able to fix the problem as you make the adjustment. You should be able to shift smoothly through every gear.
8. Issues With Freehub/Cassette Or Freehub/Hub Shell Interface
Check whether the cassette is positioned correctly on the freehub.
Clock the sprocket well so that it is where it belongs.
If your mountain bike’s free hub pawls are worn out, it is possible for the freehub to slip under load, which could be mistaken as the chains are slipping.
How To Prevent MTB Chain From Slippage (In-Depth Video)
9 Steps To Take Good Care Of The Chain To Prevent Slippage?
A drivetrain consists of a cassette, chainrings, rear derailleur, and the chain itself.
The primary cause of slippage is an accumulation of dirt and grime on the drivetrain.
Hence, it is essential to properly clean and maintain your bike’s drivetrain to improve its lifespan.
Follow the nine step chain cleaning guide stated below to prevent the slippage of your mountain bike chain.
- The first step to cleaning your mountain bike’s chain is to hang it on a stand or turn your bike upside down.
- Scrub the chain using a rag and a bio degreaser. If you don’t have a bio degreaser handy, substitute it with isopropyl alcohol. You can use a small amount of either of these on a damp rag and press it gently over the chain using one hand.
- Next, pedal the bike using your other hand in a way that the chain runs through the rag 2-3 times.
- Put pressure on the top and bottom of the chain for 2-3 cycles and on the sides for the subsequent few cycles. In the process, if you find any dirt or grease, scrub them away using the rag.
- Clean your mountain bike’s gears using a toothbrush or a bicycle brush dipped in biodegradable solvent or isopropyl alcohol.
- Try using a screwdriver to scrape off the dirt in areas where the toothbrush does not reach. A screwdriver is always an excellent tool to get rid of the grime on pulleys and rear derailleur.
- Using a rag, wipe off any dirt that you may find on chainrings and the derailleur.
- Invest in a chain cleaner to remove grime off hard-to-clean chains.
- Lube your bike’s chain after the cleaning process. A single drop of lube to every 2-4 links would be sufficient. After the chain, shift through the mountain bike’s gears and apply 10-12 drops.
Related: In-Depth Guide On MTB Chain Cleaning
7 Frequently Asked Question About MTB Chain Slippage
1. How tight should my mountain bike chain be?
Pull your mountain bike chains away from the position it currently is in, and they should move up or down about half an inch from their original position.
Having no slack in the chain means that it is excessively tight, which is also not recommended.
While loose chains are more prone to slipping off and damaging the associated parts, too tight chains are also detrimental to the mountain bike.
Hence it is vital to maintain the recommended slack of about half an inch.
2. How do I know if my bike chain is too loose?
It is similar to checking the tightness of your mountain bike.
Pull the chain away from the cassette of your mountain bike.
If you are able to pull more than half an inch of the bike away from its sitting position, you can conclude that the bike’s chain is too loose.
3. Does a loose chain affect power of your mountain bike?
When your bike’s chain is loose, you will have to put more effort into pedaling.
This is because the slacker your bike’s chain, the more energy you will have to put into it as the power drops.
4. What happens if the bike chain is tight?
If your bike is a multi-speed one with a derailleur, you shouldn’t worry too much about a chain that is too tight.
However, for single-speed mountain bikes, chains that are too tight may cause friction.
This can lead in to increased force on different parts of the drive-chain and excessive wear.
5. How do I tighten my mountain bike’s chain?
You can quickly tighten a loose bike chain to prevent it from slipping away.
For a single-speed bike, the first step would be to loosen the rear axle.
Next, you have to pull the rear tire back to improve the tension of the chain.
Then, tighten the rear tire again, and you are ready to go!
If your mountain bike’s chain is sagging, you have to twist the screw at the back of the derailleur in order to improve the tension.
Next, adjust the rear axle to make the chain tight.
Finally, put everything back in place, and you can now shed all your worries about a sagging chain.
6. How do I fix my bike chain when I can’t hang it on a stand?
Hanging your mtb on a stand is the best way to do your job well.
However, it may not be possible if your chain slips while you are on the road or a trailside.
In such cases, you can fix and set the front of the seat over a large pole (horizontal).
The idea is to keep your bike 4 feet off the ground or high enough so that the rear wheel is not in contact with the ground.
7. How often should you check chain slack?
There is no hard and fast rule as to how often you should check your chain slack.
However, it is good to give it a check once in a while, as a part of your routine mountain bike maintenance check.
7 Easy Steps To Follow For Fixing A Slipped Bike Chain
By now, you may have got your answer for why does my chain keep slipping off my mountain bike.
Now, if you want to know how to fix a slipped bike chain step-by-step, here you go:
- Inspect the chain, and tighten it.
- Inspect the cassette, derailleurs, and limit screws. Make necessary adjustments as required, or make replacements as per your judgment.
- Hang your mountain bike on a stand, or turn it upside down, so that your bike stays in place while you make necessary inspections and adjustments.
- Flip the mountain bike in a way that it rests on the handlebars and the seat, and set it down softly without causing any scuff or scratch.
- Adjust your front gears using the left hand and back gears using the left hand.
- To get slack on the chain, you have to push the rear derailleur arm toward the handlebars. You will find this beside the cog on the lower portion of the derailleur.
- The tiny metal square button is there to help you push the derailleur sans any greasy mess.
- Make sure it folds slightly in the direction of the bike’s front to get the chain hang with a generous amount of slack.
- With your other hand, slide the chain back into the right gear. If you are not comfortable using your fingers, use a pencil or a pen to put the chain back into the gears.
- Now, gently pedal backward using your hand for one full rotation.
Persistent thoughts like “why does the chain keep slipping off my mountain bike,” may lower your enjoyment level while you are on the trails.
Proper identification of the problem and fixing the issue of chain slack before you hit the trails will not only give you a better experience but will also save a lot of time and energy on the trails.
Especially when you are riding as a group, it is better to have all your bike’s problems fixed beforehand.
P.S. If you found this guide to be helpful, we have similar resources on short and long MTB chains, how to choose MTB chains and mountain bike maintenance.