Repairing a Broken Chain

Introduction

Bikes are generally quite reliable machines. Punctures are common but apart from that, what else might go wrong with your bike whilst you're away on a trip? Well for one thing, you might be unlucky and suffer a broken chain. It does happen. Chain links weaken over time and may eventually break. And it only takes one link, of course.

If your chain breaks, you will need a new chain and cassette fitting as soon as possible. But how do you get home or to the next available bike shop in the meantime? Yes, you could walk. But that's not the first choice, especially if you're 30 miles from the next town. So what could you do and what do you need to carry?

Options

You have two options. You could repair the chain using chain connector links (sometimes called quick links) or you could repair it using one of the rivets from the chain itself. In either case you will need to remove the two ends of the broken link and maybe an additional link, depending on the approach you choose to take. As for tools, you'll need a chain breaker or a multi-tool which includes a chain breaker and a pair of pliers might be useful, especially if you intend to use a chain rivet rather than quick links.

Chain links

Chains are made up of links. Each link is formed from two plates and a rivet which goes through holes in the plates. Take a look at your chain and notice how links alternate in size, with one size sitting snuggly inside the larger size.

Removing links from the chain

I carry a Park Tool I-Beam 3 multi-tool which includes a chain breaker.

Park Tool multi-tool with chain breaker to the left

It's remarkably easy to use. Just place the link to be removed onto the slot in the chain breaker, with the rivet aligned with the screw-in bolt, tighten by hand and then apply more force using your tool's built in handle or in the case of a multi-tool like mine, use the provided tyre lever which doubles as a spanner.

Removing the broken link - note spanner at top of photo

Close up showing the link positioned in the chain breaker

About to start using the chain breaker

Note the rivet being driven out

Repairing using a rivet from the chain

Prepare the chain by removing the broken link. This should leave you with a chain which has an inner link at one end and an outer link at the other, as shown in the next photo.

You should have two rivets that were removed to allow the broken pieces of link to be disconnected from the chain.

The goal now is to repair the chain by joining the two ends using one of the rivets that was removed. First, run the broken chain around your cassette and chain ring and through the front and rear derailleur. Make sure you do this properly. The chain should run over the top of the top jockey wheel of the rear derailleur and under the bottom jockey wheel. There's also a small bar inside the rear derailleur between the top and bottom jockey wheels. The chain should run behind this.

With the chain in place, you'll use your chain breaker tool in reverse, to push the rivet back through the links to join them again. To make life easier, flip the chain off the front chain ring so it sits on the crank, giving you much more slack in the chain.

It's a bit tricky. You need at least three hands! I managed to put the two ends together (one inside the other) and then get the rivet to just about stick in the hole using pliers. I could then place the link in the chain breaker tool without the rivet moving or falling out, make sure it was properly aligned with the chain breaker's pin and then tighten it up, pushing the rivet all the way through. Be patient. It can be done!

Pushing a rivet back through the hole to join the chain in place on the bike

Important! Your chain is now a couple of links shorter than it was before. Therefore, it is best not select gears which use the largest cogs on your cassette and the largest ring on the front chain ring. The combination of the two largest cogs require the greatest length of chain and you may well no longer have enough. The idea of this repair is to get you home or to a bike shop, remember. So be careful with gear selection if you want to avoid causing further damage.

Repairing with Quick Links

Quick links are great but you need to make sure you're carrying the right size in your saddle bag for when disaster strikes. That's right. Just as chains come in different sizes, not surprisingly so do quick links. The issue is that the more gears your bike has, the more cogs it will have on the cassette and so generally, the thinner the chain has to be. And quick links have a pin which passes through a chain link and so the pin has to be the right length.

Chains are for 8 speed, 10 speed or 11 speed bikes (etc) so make sure you buy quick links that are compatible with the chain on your bike.

To prepare your chain for repairing it with quick links, you need to remove the broken link and one additional link so that both ends are of the smaller, inner link type as shown in the next photo.

To make the repair, you need two quick links, like these:

Insert the pin of each quick link into an end of the chain and snap onto the protruding end of the other quick link so that the chain is joined. At this stage the chain is loosely connected and not usable. To complete the repair, apply the rear brake and apply force to a pedal so that the chain tensions and the quick links should snap into place fully. It's really easy and absolutely my preferred option of the two. It's good to know that there's another way though if you should happen to find yourself without quick links (or the wrong size!).

Conclusion

With the right tools and perhaps a handy couple of quick links you can fix a broken chain out on the road and get to a place where you can buy a new chain and cassette. Practice makes perfect though, so I recommend you have a go at making one of these repairs at home before you have to do it for real out on a trip, miles from civilisation!