A broken or mangled chain is fortunately not a common occurrence, but it can certainly end a ride fast.
And depending on how the chain fails, it could rip off your rear derailleur, bend chainrings, or even damage your frame!
Preparing to address a broken chain is simple and the tools required take up minimal room with your flat tire repair kit.
The two necessary pieces are a compact chain tool, such as this Park Tools CT-5 or Crank Brothers multi-tool with an integrated chain tool, and a master link, such as a KMC Missing Link or Sram Power Link, to easily join two chain links.
While not necessary, I’d strongly recommend keeping some disposable vinyl gloves in your bag as well to keep your hands clean (unlike mine in the following pictures!), and as a bonus, they’re great to have if you ever need to tend to someone else’s injury and want to minimize blood contact.
First, you’ll want to locate the damaged or broken link and remove it with the chain tool. Sometimes the damaged link just has an outer plate coming off one of the pins, other times a link completely snaps and you won’t have a hard time finding it at all.
Using your chain tool, remove the outer plates of the damaged link of the chain – or however many links are damaged – so that you have an inner link at each end remaining.
Next, wind the chain around your chainrings, starting from the bottom and around the top, so that both ends are on above the frame’s chainstay at the top side of the chain’s “loop” and attach both inner links using your master link.
Be sure to keep the chain fed through the rear derailleur during this process – it’s not necessary but makes the job a whole lot easier.
Normally at this step, you could use master link pliers, such as the Park Tools MLP-1.2, to join the chain back together, but you’re likely to not have one of those with you on a ride!
A simple trick that you can do instead (and this is precisely why you should set up the master link above the chainstays) is to stand next to your bike, squeeze your rear brake lever, and then stomp on your pedal with your foot like shown in the picture below. You’ll hear a pop as the master link snaps into place.
Now that the master link is secure, spin the crank around a few times to make sure the chain is secure and rolling freely on all the teeth on the chainrings, cassette, and derailleur.
Keep in mind that if you had to remove more than one link your chain some gear combinations using the big ring (or in the case of 1x drivetrains, the biggest cassette cogs) may not be usable anymore due to having a shorter chain.
Once that’s all set you’re good to get pedaling, hopefully with a smile on your face knowing that you were able to remedy the problem yourself without calling for someone to pick you up!
All of the tools mentioned in this article are shown below;