Why Does My Bike Chain Slip When I Pedal Hard?

Mountain bikers often face this issue where they hear a sudden popping noise from their rear wheel when they’re pedalling hard or after the terrain changes.

This is caused when the bike chain is slipping on gears or skipping gears. It is a common issue and there are many causes to it.

What Causes Bike Chains To Slip?

There are many reasons why even newly bought bike chains may skip. You’ll have to conduct a thorough checking of related bike components to figure out what is causing your chain to skip gears.

  • Worn out cassette cogs: If you’ve been using your bike for a while now, your cassette or freewheel cogs have probably worn out. Worn out cogs are harder to grip and the chain will slip to the next gear, causing your bike to jump.
  • Too long chain: If your chain is too long for your cassette, it will get caught in the derailleur or in the cassette, causing skipping.
  • Use of too much or too little bike grease: If your chain is dry, whenever pressure is applied due to gears shifting, it will get caught in between the cassette cogs. Again, too much grease being present in between your drivetrain parts will also make your chain slippery and it will fall off to lower cogs and shift to higher gears.
  • Derailleur shifting: If your bike’s derailleur shifts into a lower position, the chain will get pulled back while riding. As a result, the chain may get stuck or skip gears while shifting. The chain may even experience fandom shifting when the riding terrain changes slightly or when pedalling speed is changed.
  • Incompatible drivetrain parts: The cassette, chain, chainring, derailleur – all these parts together are your bike’s drivetrain. The chain needs to be bought after matching cog sizes with the chain’s capacity. All these components need to be compatible in order for your bike to run smoothly. If the chain doesn’t fit the cassette or it’s too long for the derailleur to control, you’ll experience chain skipping or slipping.

How Do You Fix A Slipping Bike Chain?

As mentioned before, you’ll need to check each of your bike parts to find out what’s causing the chain to skip. Examine all the parts and figure out what the issue is first.

If the chain is simply caught in the wrong cog due to heavy riding, try these general
solutions:

  • Before dismounting your bike, shift your bike to the lowest gear so that the chain rests on the largest cog. Keep pedalling backwards. This may solve the chain slipping issue.
  • If that doesn’t work, dismount your bike and lift your rear wheel. Keep spinning the pedal with your hand then push the derailleur forward. This should release any tension on the chain. Lift the chain up and place it back on the chainring. Keep turning the pedal with your hand while the rear wheel is still lifted to align the chain. This step is a little messy so use a pair of gloves to avoid greasing your fingers.
  • Grease your bike chain and cassette and remove all the extra grease before riding.

How To Fix A Slipping Bike Chain If The Chain Is Too Long?

Use a chain breaker tool to break a chain link. You can learn more about breaking bike chains here. You’ll need to break two chain links so you can make your chain shorter and connect it. Don’t take the rivets completely out of the link’s cavity as it is very difficult to insert it into the slot again.

Step-2: Readjust the derailleur

If your derailleur has shifted, you’ll need to insert the chain properly through the derailleurs pulleys.

  • Insert the chain along the higher pulley (also called guide pulley) then through the derailleur cage between the two pulleys.
  • Pull the chain over the second pulley (tension pulley) and through the drivetrain.

Connect the two ends of the chain using the chain breaker tool. Position the link so that the rivet is facing towards the pin of the tool. You can learn more on reattaching bike chain links here.

Take off your chain and bend it around to see which links are stiff. The stiff links won’t move as easily as the other links.

  • Try wiggling the links, holding the chain with both hands in an up and down and side to side motion. The chains should move a bit more flexibly now.
  • If this doesn’t work, try using chain grease and again wiggle the links to see if they’re moving.
  • You might need to use the chain breaker tool to loosen the links if the other ways don’t work. Just place the links on the inner slot of the chain breaker tool and push the pin on the link’s rivet until its position is adjusted. Try shaking the links again to see if the chain is now flexible.

Position your chain in the chainring and pedal backwards to see if it runs smoothly or not.

How To Fix A Slipping Chain If The Derailleur Needs Adjustment?

  • Step-1: Check if the derailleur is somehow damaged or if the derailleur hanger is bent.
  • Step-2: Adjust the barrel adjuster to check if the shifter is working properly.
  • Step-3: Shift the derailleur forward and place the chain on the cassette again.
  • Step-4: Pedal the chain backwards to check if it’s properly running without skipping.

How To Know If Your Bike Chain Is Worn?

A worn bike chain will cause gears to shift on their own when there is any change of pressure on the bike. To check if a bike chain is worn, use a chain gauge. Your chain may need replacing if it is too worn as it will wear out the other bike components as well.

If you find that your drivetrain parts are incompatible.i.e. your chain doesn’t work with the current cassette or if the derailleur shifts too much, you will need to find compatible components from a cycle shop. This would be the right time to head over to a bike repair shop and let them have a look at your bike.

Conclusion

You need to constantly inspect your bike parts to see if they’re all working the way they’re supposed to be working. If you’re facing any issues like chain slipping, gears skipping, pedalling problems – all of these have reasons. The better you know your bike, the easier it’ll be for you to identify the obstacle and the quicker you can start on resolving it.

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