Master Link

So your bike chain fell off …

Once you’re done screaming into the sky and whacking the nearest tree trunk with the biggest stick you could find, let’s help you get that chain back on. And once that’s out of the way, we can offer a few pointers to keep it from falling off again. We at Jans absolutely advise that all your bicycle maintenance is performed or overseen by an experienced bicycle mechanic – but here’s some info to carry you through until you get back to the bike shop.

How to put your bike chain back on:

Step 1: Before putting your chain back on, you first want to make sure that it’s still in working order. If your chain has been damaged, you’ll need to replace all the affected links. Simply reassembling a broken chain with the same links that broke in the first place puts you in prime position to break it again. Unless you have spare links available and are well-versed in chain maintenance, seek the help of a qualified bicycle mechanic to remedy or replace your chain if it is damaged.

Step 2: If your chain is in good working order, next, shift your rear derailleur into the highest gear. If you have a front derailleur, shift it into the lowest gear. This means that both your derailleurs are hovering over the smallest rings in your drivetrain. This position puts the least amount of tension on your derailleur cables and chain.

Step 3: Starting with your rear derailleur, pull the chain back like you’d pull an arrow in a bow, guiding it with the upper pulley as needed. When the chain is over the highest (smallest) gear, slowly lay it over the teeth, from rear to front, on the top of the cog.

Step 4: Once the chain is sitting properly on your rear cassette, pull the slack from under your front chainring. Lay the links over the the top of the chainring until several teeth are engaged.

Step 5: Once teeth are securely engaged, pedal through a few strokes to assure the drivetrain is pedaling smoothly. Be sure to keep your fingers clear of the drivetrain while the chain is in motion.

Step 6: Before you hit the trail, you may want to shift out of the gears you used to get the chain back on. Shift into a moderate gear, and take a spin.

To assure it doesn’t happen again:

  • Assure your derailleur hanger is straight. This entails standing behind your bicycle, and looking at the chain as it travels up from the bottom pulley, around the upper pulley, and over the cassette. These three points of contact should form a straight, vertical line. If the line is crooked or diagonal, your derailleur or derailleur hanger may be bent, and may require adjustment or replacement.
  • Make sure your chain is the right length. Having too many or too few links in your chain can contribute to drivetrain issues. Assure that your chain is the right length for your drivetrain.
  • Check your limit screws. The limit screws on your derailleurs limit how high or low the derailleur can move. They’re typically labeled “H” and “L” respectively. If your limit screws are not properly set, it can cause the derailleur to push the chain off the rings. Shift into the highest and lowest gears, and apply added pressure as needed to see if the derailleur can push the chain off the rings. If the derailleur pushes the chain off the high or low rings, tighten the limit screws accordingly.
  • Go over your chainrings to make sure no teeth are missing. Broken drivetrain components–especially chainrings or cogs–can cause chains to drop, and can contribute to further damage. Replace all damaged drivetrain components before attempting to ride again.
  • Assure that all your drivetrain components are compatible. Drivetrain components are very specific. Everything from the width of the chain to the spacing of the teeth has been uniquely designed to be run with a specific kit. Mixing components from incompatible brands or kits can prevent your drivetrain from working properly.

Hopefully some of these pointers have helped quell your frustration and get you back on the trail. If something in your drivetrain is still amiss, consult with a professional bicycle mechanic as needed to fully resolve your mechanical issue.

Bent Link
This chain has a bent link. Photos courtesy of Park Tool.
Stiff Link
This chain has a stiff link. Photos courtesy of Park Tool.
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