Having a bike chain that slips while riding can be annoying, inconvenient, and even dangerous. A slipping chain indicates a problem somewhere in your bike’s drivetrain that needs to be addressed.
When your legs are churning and your bike chain starts making noise and jumping around instead of smoothly transferring power to the rear wheel, it’s extremely frustrating. A bike chain that slips can also cause you to lose pedaling efficiency and power. At best, it’s just an annoyance, but a severely slipping chain can cause you to lose control and crash.
Fortunately, with some detective work and basic bike maintenance, a slipping bike chain can often be fixed quickly and easily. Here’s a comprehensive look at the common causes of a slipping bike chain and step-by-step instructions for how to properly fix it.
What Causes a Bike Chain to Slip?
There are four main potential causes of a slipping bike chain:
1. Worn Out Cassette or Chainrings
The most common cause of a slipping bike chain is worn out cassette cogs or chainrings (front gears). As these components wear over time, the teeth become thinner and more elongated. This causes the chain to not mesh and seat properly, resulting in slippage. Replacing a worn cassette or chainrings will commonly fix the problem.
2. Stretched or Damaged Chain
Over time, chains naturally stretch and elongate through normal use. As each link wears, the overall length grows. This can cause the chain to skip and slip on the cassette cogs and chainrings. A bent, stiff, rusty, or otherwise damaged chain can also slip. Replacing a worn chain often solves slipping issues.
3. Poor Chainline Alignment
The chainline is the imaginary straight line that runs from the front chainrings to the rear cassette. If the chainrings, cassette, or derailleurs become bent or misaligned, it can throw off the chainline and cause skipped links and slippage.
4. Dirty or Unlubricated Drivetrain
Dirt, grime, mud, and lack of lubrication cause excessive drivetrain friction and wear. This dramatically accelerates chain, cassette, and chainring wear, leading to slippage problems. Proper cleaning and lubrication prevents premature component wear.
Now that you know why bike chains slip, let’s go through how to diagnose and fix the problem for good.
How to Diagnose a Slipping Bike Chain
When you experience chain slippage issues, don’t just try randomly replacing parts and hoping for the best. With some inspection and testing, you can properly diagnose the cause and fix it right the first time. Follow these steps:
Step 1: Thoroughly Clean the Drivetrain
Before diagnosing anything, thoroughly clean the chain, cassette, chainrings, derailleurs, and crankset. Built-up dirt and grime can easily cause drivetrain issues. Degrease and scrub off all debris to rule that out as the culprit.
Step 2: Lubricate and Check for Damage
After cleaning, thoroughly lubricate the chain. As you apply lube, inspect the chain closely for any stiff, bent, rusted, or warped links. Also check for chain roller wear. Damaged and excessively worn chains commonly cause slippage.
Step 3: Inspect the Cassette and Chainrings Closely
Examine the teeth on each cassette cog and chainring. Do the teeth have a visible shark-fin shape? Are the tops thin and sharp? If so, they are likely excessively worn and need replacing. Even just one worn cassette cog can cause slippage.
Step 4: Check Chain Wear with Gauge or Ruler
Use a chain wear gauge tool or a 12-inch ruler to measure chain stretch. Lay the ruler along the lower run of chain. If 12 full chain links measure 12 1/8 inches or more, your chain is worn out and needs replacing.
Step 5: Spin the Crank and Check for Slippage
Turn the bike upside down. Spin the cranks forward with your hand and shift through every gear combination while observing the rear wheel. If the chain slips at all, on which cogs does it slip? That narrows down the issue.
By methodically cleaning, inspecting, and testing step-by-step you can accurately determine why your bike chain is slipping and tackle the root cause.
How to Fix a Slipping Bike Chain
Once you’ve diagnosed the problem, fixing a slipping bike chain is usually a straightforward process:
Step 1: Replace Any Worn Out or Damaged Parts
Based on your diagnosis, replace any worn out cassette cogs, chainrings, or damaged chains. Installing new parts often completely fixes drivetrain slippage issues.
Tip: Only replace the individual worn cogs, not necessarily the whole cassette.
Step 2: Verify Proper Chainline Alignment
Make sure the front chainrings, rear cassette, and derailleurs are properly aligned. The chain should move in a silky straight line without kinks or bends from front to back. Adjust as needed if issues are found.
Step 3: Index the Rear Derailleur
Anytime major drivetrain parts are changed, the rear derailleur likely needs re-indexing to accommodate the new components. Follow the indexing steps in your derailleur manual to dial in smooth, crisp shifting.
Step 4: Lubricate Thoroughly After Fixing
After fixing any drivetrain issues, fully lubricate the chain, rotating through all gears to work the lube into each link. This prevents accelerated re-wear of components.
Tip: Use a quality chain lube formulated for wet or dry conditions. Wax-based lubes tend to last longer.
With worn drivetrain parts replaced, proper alignment restored, and fresh lube applied, your bike chain will stop slipping and you can get back to smooth, powerful pedaling.
Advanced Diagnosis and Fixes
More complicated slippage issues may require advanced diagnosis and drivetrain work. Here are some additional steps to try if basic fixes don’t solve your bike chain slipping:
- Use a chain wear checker tool to measure stretch at multiple points along the chain’s length. Irregular wear indicates a bent chain or stiff link that needs replacing.
- Check the rear hub, cassette lockring, and freehub body for looseness or damage which could allow cassette wobble and chain slippage. Tighten or service as needed.
- Examine the rear derailleur hanger alignment using a special tool. Bent hangers can prevent smooth chainline transit and cause skips.
- Assess chainring and cassette cog tooth profile for irregular sharkfin wear indicating damaged, bent or out-of-true parts. Replace affected components.
- Try a new chain on the current cassette and chainrings. If slippage is fixed, you may only need a new chain.
- Install a chainring guard to prevent debris buildup and extend component life to avoid slippage over time.
- Upgrade to higher quality chains, cassettes and chainrings which typically last longer and shed contamination better.
While extra work, these advanced troubleshooting steps can solve even the trickiest chain slippage when basic fixes fail.
Maintaining Your Bike to Prevent Chain Slip
Prevention is the best medicine when it comes to bicycle drivetrain issues. Follow this essential maintenance plan to avoid a slipping chain:
- Keep it clean: Wash your bike after muddy, dusty or wet rides. Hose or wipe down the chain, cassette, chainrings and derailleurs. Let it dry fully.
- Lubricate frequently: Apply bike chain lube every 100-200 miles. Oil attracts grit so only reapply when prior lube is washed away or dried out.
- Replace chains yearly: Chains elongate as they wear. Install a new chain roughly each season to avoid slippage.
- Inspect parts routinely: Examine your chain, cassette and chainrings periodically. Look for stiff links, sharkfin teeth, and excess elongation indicating replacement time.
- Tune and adjust: Make small rear derailleur adjustments as needed to maintain crisp shifting. Indexing periodically helps avoid drivetrain slippage.
Following proper cleaning, lubricating, replacing, inspecting, and adjusting protocols keeps your drivetrain running smoothly for miles. invest in quality components and any slipping chain issues should be few and far between.
Troubleshooting a Slipping Bike Chain FAQs
Still have questions about diagnosing and fixing a slipping bike chain? Here are answers to some frequently asked questions:
What is the easiest thing to try fixing a slipping chain?
Thoroughly cleaning the chain, cassette and chainrings then applying fresh bike chain lube is the quickest and easiest fix for many minor chain slippage issues. Proper lubrication prevents accelerated drivetrain wear and debris buildup.
Can I just replace a slipping chain without changing the cassette?
You can try installing a new chain first as it may fix issues caused by chain stretch or damage. But if the cassette is worn out it will rapidly re-wear a new chain causing persistent slippage until replaced.
What tools do I need to work on a slipping bike chain?
Basic bike maintenance tools like degreaser, lubricant, brushes, rags, hex wrenches, a chain tool, and a chain wear checker tool are essential for diagnosing and fixing chain slip issues.
Should I take my bike to a shop if the chain keeps slipping after adjustments?
If you’ve methodically cleaned, replaced worn parts, re-lubricated and re-indexed but the chain still slips, it’s best to take it to a professional bike mechanic. There may be a more complex underlying issue needing expert repair.
How can I prevent my bike chain from slipping in the first place?
Regular cleaning, frequent proper re-lubrication, annual chain replacement, inspecting parts for wear, tuning the derailleur, and using quality components are key ways to minimize chain slippage over long-term use.
Properly maintaining your bike drivetrain keeps your chain running smooth for miles of slip-free riding.
Dealing with a slipping bike chain can definitely be frustrating and disruptive to your cycling enjoyment. But in most cases it is an easily diagnosed and repaired issue.
The problem usually boils down to worn out cassette cogs or chainrings, a stretched chain, damaged chain links, or general drivetrain contamination and lack of lubrication.
By methodically cleaning, inspecting, measuring, and testing the involved components, you can accurately pinpoint the root cause and implement the proper fix. Replacing worn parts, realigning the derailleurs, indexing the shifters, and applying fresh chain lube typically solves the problem quickly and cheaply.
Implementing consistent drivetrain cleaning, frequent lube application, regular chain replacement, and component inspection will minimize issues and help prevent problematic chain slippage from occurring. But when it does happen, now you know how to efficiently diagnose and repair it to get smoothly and safely back in the saddle.