What a broken chain feels like
When a chain snaps or comes apart, the pedals suddenly spin with no resistance and the bike stops driving forward. Sometimes there is a clunk or a metallic clatter first. Your foot can slip off the pedal when the load disappears, so the first moment is the risky one.
Stay calm, keep your hands on the bars and stop pedalling. Do not try to pedal on. A chain that is broken, partly detached or badly damaged should not be ridden, because it can jam in the drivetrain, throw you off balance or damage the bike.
Stop safely first
- Check behind you and signal if you are on a road or shared path.
- Coast and brake gently. Your brakes still work, but remember that a sudden hard grab, especially on the front brake, can unsettle the bike.
- Move off to a safe place, away from traffic and from people walking.
- Stand the bike where it will not fall over, and look at the chain.
Check the dangling chain and the area around the rear wheel and chainring for sharp or jammed bits. Handle greasy parts carefully.
Look at what actually happened
There are two common situations. In the first, the chain has simply come off the sprockets or chainrings. That is a derailed chain rather than a broken one, and it can often be put back by hand. In the second, a link has failed and the chain has separated into two pieces, or a plate has cracked or bent.
If a link is bent, twisted, cracked or stiff, treat the chain as damaged. A chain that has lost a link may also be short enough to put strain on the gears, so repair needs care. If the chain has been showing its age, with skipping gears or stretching, it may have been due for replacement anyway. Knowing how to tell chain wear helps you spot this before it fails.
Option one: a quick link
Many chains today are joined with a quick link, sometimes called a master link, which can be opened and closed without special tools in many cases. If your chain failed at or near the quick link, or if you carry a spare compatible with your chain, you may be able to rejoin it.
The idea is simple:
- Remove any damaged links so that you are joining sound ends.
- Bring the two ends together and fit the quick link as its instructions describe.
- Make sure it is fully seated and clicked into place before you ride.
Quick links are made for specific chain types, so a spare must match your chain. Follow the manufacturer’s instructions for your chain and link; if you are unsure, ask at a bike shop. It helps to know which basic bike tools are worth carrying, because a small chain tool and a spare link can turn a long walk into a short delay.
Option two: a chain tool
A chain tool pushes a pin out of a link so you can remove a damaged section, then rejoin the ends. This is more delicate than it sounds. Pushing a pin too far can leave a link unusable, and the rejoined chain may be a little shorter, which limits which gears are safe to use.
For a roadside repair, riders usually choose a gear in the middle of the range and avoid extremes, because a shortened chain can be strained in the largest chainring and sprocket combination. This is the sort of thing a mechanic can check and explain properly. Treat any roadside repair as temporary and take the bike for a proper check afterward. Good guides on roadside repairs go through this in more detail, and a bike shop can show you in person.
Option three: coast and scoot
If you have no tool, no spare link, or you are not confident in the repair, there is nothing wrong with getting home without the drive. Depending on where you are, you might:
- Walk the bike. It is the simplest and safest choice, especially on a busy road.
- Coast downhill where the way is clear and safe, then walk the flat or uphill parts.
- Scoot by sitting on the saddle and pushing along with one foot on the ground at low speed, only on a quiet, flat, traffic-free surface and with a helmet on. This is slow and takes care, and walking is often better.
- Phone a friend or family member, a taxi or a bike shop for a lift if you are far away or it is getting dark.
Be honest about your situation. If it is dark, raining or the road is busy, being seen matters more than saving time. Check your bike lights are on if you are walking in poor light.
What not to do
Do not ride on a damaged chain, and do not tie it, tape it or force it together in a way you cannot trust. Do not put your fingers near moving gear or chainrings while turning the pedals to test something. And do not push on hard just because the repair looks neat; a chain that fails again under a hard pedal stroke can send your foot off the pedal.
After you get home
Have a good look at the whole drivetrain. A chain rarely fails alone: a worn cassette, a bent link from a bad gear change or a poorly fitted quick link can be the starting point. Clean the parts, check that the shifting works and that there are no skipping gears under load. If you did a roadside repair with a chain tool, replacing the chain with a new one is often a sensible next step, although a shop can advise on the best option for your bike.
Finally, a little preparation helps. Carry a small chain tool or a matching quick link along with your other repair kit if you ride far from home, and learn the repair at home, in the dry, with the bike on a stand or upside down, before you need it on the road.