You and your bicycle have a closer bond than you realize.
Just like your skin, when the bike ages, the chain sags.
But don’t fret. You don’t need a plastic surgeon or great self-confidence to fix the problem, just some know-how.
Here’s the quick down and dirty on how to shorten a bike chain:
- Measure the chain to determine if it needs replacing.
- Detach the chain.
- Grab a chain tool, or pliers and a small nail.
- Pop the rivets, and remove the unwanted links.
- Measure the chain.
- If it fits, reattach it and lubricate.
General Chain-Shortening Tips
All bicycles are different, and you may want to research your bicycle brand in advance. Mountain bikes often need extra research.
I’ll be teaching you how to deal with basic, common chains. Even with these, before you attempt the process, there are some tips to keep in mind:
- Test the chain before, during and after shortening: Pushing the pedals with your hands is fine. However, you need to go for a short cycle to ensure optimum performance. Just because the chain fits and doesn’t sag, it doesn’t mean it’s the perfect length.
- Consider consulting an expert: If your bicycle or chain were extremely expensive, consider going to a professional. Your bicycle should go in for a yearly tune-up anyway, so perhaps make the chain shortening a part of your next one.
- The need to shorten isn’t always obvious: Your chain may not appear or feel slack and still require shortening. If you ride in harsh weather conditions or on bumpy terrain, consider measuring the chain. The jolts could’ve loosened the chain.
Important: Before You Start, Consider…
Please don’t make my mistakes. I often skip to the “how to” section, then follow along without reading it first.
Doing it like me will ruin your bicycle chain. Instead, read first, shorten later:
Can You Get the Chain Back On?
If you can, skip ahead.
But, if you’re like some people I know, who assume they can do things they’ve never tried… don’t do that.
I won’t teach you how to put a bike chain back on today, but if you’re not confident, consider asking a friend for help.
Then move onto the next consideration.
Do I Need to Shorten the Chain?
If you have mobility issues while cycling, it may not be the chain.
But, if you’re convinced it is, take some measurements first.
What to Measure
Measure the first 12 links. If you're coming up over 12 inches, it’s a sign the chain is separating. It’s time to shorten it.
Also, factor in…
The process to shorten a bike chain below works for road bikes and similar steeds. Mountain bikes are a little more complicated—so I wouldn’t recommend tackling this as a novice mountain bike owner.
How To Shorten a Bike Chain
There are two ways you can shorten a bicycle chain. I recommend the first, in which we use a chain tool. I find it more practical, but it’s up to you.
Method 1: With a Chain Tool
If you don’t own a chain tool, the Oumers Bike Link Plier and Chain Breaker Splitter is inexpensive yet effective. Best of all, it’s universal—use it now and on any future bicycle.
Step 1: Remove the Chain
You can keep the chain on if you wish, but you’ll need a bike stand to keep your steed steady. I find it more practical to take the chain off to have better access to the links.
I have a full guide on how to remove a bike chain to help you here.
Step 2: Clean the Chain
You’ll need to see the bike chain’s color, so cleaning it is a smart move. Be sure to oil it afterward.
Also, take this opportunity to remove rust from the bike chain if necessary.
Step 3: Search for a Master Link
Not every chain will possess a master link. You can identify it by:
- Darker or lighter color.
- Extra bulk, like a little link-shaped mask.
- Wider hole or extra joint.
Search the entire chain’s length for this link. If you don’t find one, it’s fine. You can use your chain tool to do the job.
With a master link, remove it and store it somewhere memorable. Don’t forget the rivets, too! There should be pliers for removing this link in your chain tool set.
Step 4: Start Shortening
Without a master link, you can pick a spot and start there. Whether you start with a regular or master link, the shortening process will be the same.
Your chain tool will likely come with instructions on how to use it. Follow them carefully, as they’re likely detailed.
Here are the basics of what to do:
- Unwind the tool’s push pin.
- Slot the chain into the tool, ensuring it’s snug in the cradle.
- Tighten the push pin over the link’s rivet you want to split.
- Keep applying force, gently and slowly, until the rivet pops out—this may take some time.
- Unscrew the tool to release the pin, and the chain is now split.
Remove as many links as necessary, but don’t dispose of them. You might need them later if you made the chain too short.
Step 5: Measure and Relink
Many bicycle models come with a manufacturer-recommended chain length. Measure the entire chain, and see if it matches.
Without a recommendation, you can relink your chain and put it on your bicycle to test it. If it doesn’t sag, then you’re done.
Here’s how you relink the chain, so you can put it back on the bicycle:
- Get the master link and its rivets.
- Position it correctly, with each end of the straight chain meeting one side of the master link.
- Push the pins in until they click, using a screwdriver for strength and access if needed.
If you didn’t start with a master link, simply do the same process, but attach the ends of the chains instead.
Now you’re done, so oil your chain and get back on the road!
But, forgoing a chain tool, keep reading!
Method 2: Without a Chain Tool
Don’t be fooled; this won’t be a tool-free operation. You will need regular tools:
- Small nail.
Now, detach your chain (or leave it on if you wish) and get to work. Don’t forget to clean the chain before you start.
Step 1: Split the Chain
With a master link, splitting the chain should be easy. You can usually pop it out with a regular pair of pliers, if they’re thin enough.
Sans master link, it’s a little tricker. You’ll have to split the chain the way you’ll remove the links later.
Step 2: Decision Time
With a chain tool, you don’t have to worry. It may be a little awkward to remove links at first, but it’s not too difficult. And, it’s far from fiddly!
But without a chain tool, it’s not as easy to go link by link. Try determining all the links you’ll need to remove in one go. Consider:
- Finding out what length chain the bicycle needs, then doing the math.
- Determining how long the chain was to start, and doing that math.
You want to avoid having to reattach and measure the chain frequently.
Step 3: Link Removal
You’ll have to do this twice if you also need to split the chain this way.
But, here’s the gist of separating links without a chain tool:
- Take a nail and place it on the rivet or pin, whichever you have.
- Hit the nail with the pliers until it pops out the other side.
Try not to hit the nail too harshly, or you may damage the chain. This is why you’re using a plier over a hammer.
Step 4: Measure and Reattach
Measure your chain, and see if it’s the length you worked out. If so, perfect. Now you can reattach the master link or the two ends of the chain.
Use your screwdriver for this to ensure the click into place. Now test the chain on the bicycle.
If the chain doesn’t fit, I’m so sorry! You’re going to have to do this all again!
But, if it does, oil it up, and you’re good to go!
Shortening Mountain Bike Chains
Shortening a mountain bicycle chain isn’t always as simple as shortening other chains. Sometimes they have more rivets, particularly SRAM mountain bicycles.
High-end mountain bicycles typically have accompanying manuals. In there, you’ll find the processes to shorten their chains if needed.
Please note: you need a chain tool for most mountain bicycle chains due to the chain’s complicated mechanisms.
Please be prepared before attempting to shorten a mountain bike chain. Much of the time, the regular method works for MTBs, too.
Although I thoroughly recommend using a chain tool, you can shorten your bicycle chain with as little as a basic toolbox.
You should check on your chain every few years or after a sharp jolt. You don’t want it getting too loose! Also, make sure you give each new chain a once-over.
Keep your chain tight, but not too tight, and your ride should always go smoothly.