How to replace a bike chain (step by step)
Replacing a chain is one of the most satisfying home repairs: cheap, quick once you've done it, and it protects the far pricier parts downstream. Here's how to do it properly.
First, make sure you actually need to. Check the chain's wear — and if it's worn, do this before it takes the cassette with it.
What you'll need
- A new chain that matches your drivetrain's speed (an 11-speed chain for an 11-speed cassette, etc.). This is the one thing you can't get wrong.
- A chain tool (chain breaker), and ideally quick-link pliers.
- A rag and your usual chain lube.
Step 1: Note the routing
Before anything comes off, look at how the chain threads through the rear derailleur — over the top pulley, through the cage, under the bottom pulley. A quick photo on your phone saves confusion later.
Step 2: Remove the old chain
- If it has a quick link (master link), use the pliers (or your hands) to release it.
- If not, use the chain tool to push out any pin and split the chain.
Step 3: Size the new chain
The new chain is almost always longer than you need. Two ways to get the length right:
- Match the old chain (easiest): lay the new chain next to the old one and match it link-for-link, accounting for any stretch by going to the same number of links.
- Big-big method: route the chain around the biggest chainring and biggest cog, bypassing the rear derailleur, pull snug, then add a small amount per your chain maker's instructions (commonly one full link / an inch).
Remove the excess with the chain tool, keeping the ends able to join.
Step 4: Route and join it
- Thread the chain through the front derailleur and around the rear derailleur pulleys exactly as you noted in Step 1.
- Bring the two ends together on the lower run.
- Insert the quick link and pull the cranks backward against the brake to snap it tight — or press a connecting pin home with the chain tool (Shimano) and snap off the guide end.
Step 5: Check it
Shift through every gear. The chain should run quietly and shift cleanly.
- Skips under load in some gears? Your cassette is likely worn to the old chain — see chain skipping.
- All good? Wipe it down, add lube to the rollers, wipe the excess, and ride.
Don't forget to reset the clock
A fresh chain starts at zero wear — so note the date and your bike's mileage. That baseline is what tells you when the next replacement is due. (Tracking it per component is exactly what BikeVitals automates, so you get a heads-up instead of guessing.)