Dropped Chain On E-Bikes: Causes, Fixes, And Prevention

Nothing ruins a great ride quite like a dropped chain! And did you know there’s more than one way for your chain to slack up or detach from your bike? 

Let’s learn about the different types of dropped chain, their causes, and how to fix a dropped chain or cross-chained e-bike. This post will explain everything you need to know to get back up and riding in no time.

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What Is Dropped Chain And What Causes It?

A dropped chain is when your bike chain falls off of its front or rear derailleur, or entirely off the crankset. These are all critical pieces to shifting gears and converting your pedaling into forward momentum — so a dropped chain leaves you unable to pedal.

There are a number of things that can cause dropped chain. Here are 3 common causes to look for.

1. Wear and Damage

Worn-down parts such as bolts, cranksets, derailleurs, or the chain itself can all result in a dropped chain. Examine these parts of your bike for signs of wear or damage, and be sure to follow your e-bike’s maintenance schedule, outlined in your manual.

2. Pedaling Backward

While this was sometimes a fun trick on our childhood bikes, the derailleurs on most e-bikes are not designed to go backward. Backward pedaling will cause the chain to slack, and that lack of tension means even the smallest bump will pull your chain off.

3. Shifting Gears on Hills

Many riders find that their chain falls off when they shift gears while riding up or down a hill. The key here is that you should actually be anticipating hills and shifting gears before you hit them. To keep your chain and gears in good shape and prevent dropped chain, you want to be in the ideal gear for your hill before you hit it.

Depending on the way your chain has fallen, it may be known as rear dropped chain, front dropped chain, or cross chaining. Next, we’ll define each type and show you how to fix it.

How To Fix Rear Dropped Chain on Electric Bikes

Rear dropped chain is when your chain falls off the rear derailleur and is stuck between the dropout (where your rear wheel rests) and gear cluster (the set of metal rings that make up your gears). 

To fix rear dropped chain, push the rear derailleur cage (the mechanism that is your chain’s lowest point to the ground) forward, toward your pedals.

Correcting rear dropped chain by first pressing on the rear derailleur cage and then resetting the chain.

The tension on your chain will slack, which allows you to use your other hand to replace your chain back on the gear that your bike was in before the chain dropped.

Now take your e-bike for a quick ride and move through all your gear combinations to be sure you’re safe to hit the road.

How To Fix Front Dropped Chain On Your Electric Bike

Front dropped chain is when your chain disconnects from the chain ring, where your pedals power the chain. 

This one can be a bit trickier to fix on your own, so tag in a friend or family member if you can. To fix it, you need to push the rear derailleur cage forward while guiding the chain back onto the teeth of the chain ring.

A second set of hands may be helpful for fixing front dropped chain.

Lastly, just release the derailleur, and you’re ready to test out your gears. Ride your e-bike in a safe place and shift through all your gears. Once you’ve moved through them all without dropping the chain again, you’ll know you’re ready to ride.

How To Fix Cross Chaining On Your E-Bike

Cross chaining happens when your chain is simultaneously on the smallest sprocket of the gear cassette (rear wheel) and the smallest ring on your chainring (by the pedals), or the largest cog and the largest chainring.

If you only have 1 chainring, cross-chaining isn’t an issue. Luckily, all of Magnum’s current line of e-bikes are formatted this way, not only preventing cross-chaining but also lessening your chances of a dropped chain overall.

If you have more than 1 chainring, how do you know what gear settings will result in cross-chaining? 

Let’s say you have a 21-speed bike, with 3 settings for your chainring (front setting) and 7 settings for your gear cassette in the rear. You would be cross-chaining if you set your gears to:

  • 3-1 (with your front gear/chainring at the largest setting of 3 and your rear cog at the largest setting of 1)
  • 1-7 (with your chainring at the smallest setting of 1 and your rear cog at the smallest setting of 7)

These gear settings cause excessive wear and tear on your e-bike. They also position the chain with a fair amount of slack, which makes you much more susceptible to a dropped chain.

The exact gear combinations that cause cross-chaining vary depending on your gearing and shifter settings on your electric bike, so check your manual to be sure you aren’t regularly riding in gear combinations that can cause this. You can always step off your e-bike after shifting gears to check on your cog and chainring positioning.

Top 4 E-Bike Chain Safety And Maintenance Tips

Follow these tips to keep your chain in top shape. 

1. Clean and lubricate your chain weekly. 

  • Your chain will get very dirty with regular use
  • First, use a bike-friendly degreaser to clean
  • Then, use a bike-friendly lube to keep it moving smoothly
  • We strongly recommend avoiding spray lube — you might accidentally grease up parts of your bike that you don’t mean to

2. Keep up with derailleur maintenance. 

  • When inspecting and cleaning your chain, check your derailleurs for buildup
  • Give them a good degreasing and lubrication as needed for peak performance 

3. Watch for signs of chain or derailleur wear. 

  • Is your chain skipping when in a certain gear setting — or on all of your gears?
  • Do you experience a lag between shifting gears and the chain completing the shift?
  • Does the chain resist all shifting?
  • All of these are serious signs that you need a tune-up or potentially replacement parts
  • Take your e-bike in for service if you experience any of these issues

4. Avoid cross-chaining. 

  • If your e-bike has more than one chainring, don’t use gear settings that will cross-chain your e-bike: big-big or small-small
  • E.g., on a 21-speed bike, you have 3 settings for your chainring (front) and 7 settings for your gear cassette (rear)
  • Cross-chaining on this bike would be:
    • 3-1 (with your front gear/chainring at the largest setting of 3 and your rear cog at the largest setting of 1)
    • 1-7 (with your chainring at the smallest setting of 1 and your rear cog at the smallest setting of 7) 

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