Cyclescheme How to: Fix a bike chain

Cyclescheme, 01.01.2016

Cyclescheme How to: Fix a bike chain

A snapped chain may mean oily hands but it needn’t ruin your ride. Fixing a chain is no more difficult than fixing a puncture.

Chain wear is fact of cycling life. Most of the time it’s gradual. But occasionally the chain will snap while you’re out cycling. Fortunately it’s not difficult to fix. Here’s what you will need…

Chain tool

Workshop chain tools function best but aren’t very portable. Carry a small one like Topeak’s Super Chain Tool or choose a multitool that incorporates a chain tool.

Quick link

If your bike has derailleur gears, carry a quick link - a special joining link. Quick links are mostly interchangeable as long as you ensure you have a 9-speed quick link for a 9-speed chain, 10-speed for 10-speed, and so on; it doesn’t matter if it’s made by Sram, Shimano, KMC or whoever. However, Campagnolo 10-speed requires a quick link  designed specifically for Campagnolo 10-speed chain.

Spare chain links

If your bike doesn’t have a derailleur, carry at least one spare chain link that matches the chain. (Note: not half a link but a whole, articulated link.) You will not be able to shorten the chain – much or at all - so will have to replace rather than remove the broken link.

Wet wipes or gloves

Wet wipes will get the worst of the oil off. Gloves, such as those free ones you can get at garage forecourts, will keep your hands clean in the first place.

Fix using a quick link

  1. Give yourself enough slack in the chain to rejoin it. Shift gears to the smallest chainring and smallest sprocket, wrapping the chain around them if it’s come off. Thread it carefully through the derailleurs. Arrange the chain so that the break is at the bottom, between the end of the derailleur and the chainset.

  2. Fit the chain on the chain tool. If the tool has two sets of pegs for the chain, position it furthest from the punch so that the chain rests against the back of the tool. Screw in the tool handle and completely drive out the rivet of the broken link. You should now have a chain with an inner link (that is, a hole) at both ends. If not, drive out another rivet.

  3. Fit the quick link. The ‘rivets’ fit through the inner end of each hole. Tension the chain by hand to pull them into position at the ends of the link.

  4. That’s it. Your chain is now half a link a shorter but your bike is ready to ride. 

Fix without a quick link

You can rejoin chains up to 8-speed by removing the broken link and refastening the chain. This is possible with 9-, 10- and 11-speed chains too but it’s best as a get-you-home measure as these thinner chains aren’t designed to have their rivets driven out and in again. A shorter derailleur chain may not engage the biggest chainring and biggest sprocket simultaneously but will otherwise work fine. Hub gear and singlespeed bikes will probably need the broken link replacing rather than removing: use your spare link.

  1. Give yourself enough slack in the chain to rejoin it. For singlespeed or hub gear bikes, loop the chain around the bottom bracket inboard of the chainring.

  2. Fit the chain on the chain tool, on the pegs furthest from the punch. Making sure that the punch is centred on the rivet, screw the handle and start to drive out the rivet.

  3. Do not drive the rivet all the way out. It needs to stay attached to the outer link, with most of the rivet projecting past the outer edge and a small amount visible on the inner edge.

  4. Remove the chain from the tool and flex it at the projecting rivet to snap the chain apart.

  5. Snap the other end of the chain into place, over the inner end of the projecting rivet.

  6. Put the chain in the tool, on the pegs furthest from the punch. Carefully screw the punch onto the projecting rivet, pushing it back through the chain until it projects from the other side of the link by the same amount as the other chain rivets.

You’ll need to repeat steps 3 through 6 if you’re inserting a new chain link (or links) rather than just shortening the chain. If you’re lucky, you’re done.

If the refastened rivet(s) are stiff, they will prevent the chain from articulating. To check, bend the chain up and down or pedal the cranks backwards and watch for the chain skipping.

Free a stiff link 

This is when you use the chain tool pegs nearest to the punch.

  1. Line up the stiff rivet with the punch, with the rivet end that sticks out furthest facing the punch.

  2. Screw in the handle half a turn. As the far side of the chain isn’t braced against the back of the tool, this will spread the chain link apart a little, which should free the stiff link.

  3. If there’s still some stiffness, repeat step 2 or grasp the chain either side of the stiff link and flex it sideways, away from you and towards you. This should free it.

To refit the chain of a hub gear or singlespeed bike, you may need to loosen the wheelnuts so that the wheel can move forward to give you enough slack. If so, pull the wheel back afterwards to tension the chain, and then retighten the wheelnuts. 

As a final check for any bike: rotate the cranks to spin the rear wheel. This should reveal any problems – such as the bike being in the wrong gear or the chain being threaded wrongly through the derailleurs – before you set off. 


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