Quick answer: To put a dropped bike chain back on, shift into your smallest front chainring, push the rear derailleur forward to create slack, hook the chain over the bottom teeth of the chainring, then slowly turn the pedals forward until it seats. It takes about two minutes and no tools. The grease on your hands takes longer, so keep a wipe in your bag.
Why did my bike chain fall off?
Chains don't drop for no reason. The most common causes are:
- Shifting under load. Changing gear while pushing hard on the pedals, especially uphill, can throw the chain off the front chainring.
- Cross-chaining. Riding in the big front ring and the biggest rear cog (or small and small) puts the chain at a steep angle.
- Rough ground. Bumps, roots and potholes bounce the chain, especially if it's a little loose.
- Derailleur adjustment. If the limit screws are out, the derailleur can push the chain past the smallest or largest ring.
- A worn or dirty chain. A stretched chain, or one caked in grime, doesn't sit on the teeth as well.
What do I need to fix a dropped chain?
- Your hands (no tools needed for a simple drop)
- Somewhere safe to stop, off the road or trail
- A cleaning wipe for afterwards, so the grease doesn't end up on your grips, bar tape, face or lunch
How to put a bike chain back on, step by step
- Get somewhere safe. Pull fully off the road or trail before you start.
- Shift to the smallest front chainring. If you can, click your front shifter to the small ring and your rear shifter to a middle or smaller cog. This gives you the most slack.
- Stand the bike up or flip it. Lean it against something on its non-drive side, or turn it upside down to rest on the saddle and handlebars.
- Make some slack. Push the rear derailleur cage forward, toward the front of the bike. The chain will go loose.
- Hook the chain on. Drape the chain over the bottom few teeth of the small front chainring, at the front of the ring.
- Turn the pedals slowly forward. Lift the rear wheel if the bike is upright, or turn the cranks by hand if it's flipped. The chain should pull itself onto the ring.
- Check it runs cleanly. Make sure the chain sits on the teeth all the way round and passes through both small wheels on the rear derailleur. Spin the pedals a few times and shift through a couple of gears.
- Clean up and go. Wipe the grease off your hands before you grab your grips.
What if my bike is a single-speed?
Single-speed and hub-gear bikes have no derailleur to give you slack. Usually you can still work the chain onto the front chainring and turn the pedals. If it's too tight, you may need to loosen the rear axle nuts, slide the wheel forward, refit the chain and then re-tension and retighten the wheel before riding.
How do I stop my chain coming off again?
- Ease off the pedals for a moment while you shift.
- Avoid extreme gear combinations (big-big and small-small).
- Keep the chain clean and lubricated.
- Replace a worn chain before it wears out your chainrings and cassette.
- If it keeps happening, have a bike shop check the derailleur limit screws and the derailleur hanger.
When should I take it to a bike shop?
Stop riding and get it checked if the chain is twisted or has a stiff link, if the rear derailleur looks bent or is hanging close to the spokes, or if the chain drops again and again after you've refitted it. Riding with a bent derailleur can pull it into the wheel.
How do I get bike grease off my hands without a sink?
Chain grease is a mix of lubricant and road grime, which is why it smears instead of rinsing off. When there's no sink, a heavy-duty cleaning wipe is the easiest fix. Grease Monkey Wipes are tough, textured wipes made to cut through grease, oil and grime with no soap or water needed. Our individually wrapped wipes fit in a saddle bag, jersey pocket or frame bag, so one is there when the chain drops.
FAQ
Can I put a bike chain back on without tools?
Yes. A chain that has simply dropped off the chainring can be refitted by hand in a couple of minutes. You only need tools if the chain has broken or a wheel needs adjusting.
Should I turn the pedals forwards or backwards to put the chain back on?
Turn them slowly forwards once the chain is hooked over the chainring teeth. That pulls the chain onto the ring the same way it runs when you ride.
Why does my chain keep falling off when I shift?
Usually because the shift happens while you're pedaling hard, or because the front derailleur needs adjusting. If easing off while shifting doesn't fix it, ask a bike shop to check the derailleur.
What's the best way to clean chain grease off your hands on a ride?
Use a heavy-duty cleaning wipe made for grease. Ordinary baby wipes and paper towels tend to smear it around rather than lift it.
Chain back on. Grab a Monkey, clean up those greasy hands and get back on the bike.
