Chains

A bicycle chain is a roller chain that transfers power from the pedals to the bicycle wheel, thus propelling it. Chains are made up of a repeating series of inner plates, a roller, a chain rivet, and outer plates. The chain rivet presses into both outer plates, but the rivet slides freely through the inner plates and the roller. Chains have a small amount of play at each link, even when brand new. As a chain is ridden, it wears the rivets and the play at each link increases. This is sometimes called "stretch," although the plates do not literally become longer.

What happens when a chain is worn out?


A worn chain will not engage the cogs correctly and will eventually slip over the cog teeth when pressure is applied. It will also wear down the gear teeth. Therefore, neglecting the chain means you not only have to replace the chain (fairly cheap) but now you also have to replace the chain rings and probably a few cogs on the rear gear cluster as well. It's much cheaper to replace the chain in a timely manner.

Derailleur Capacity: Refers to the derailleur's ability to take up chain slack as the derailleur shifts between different gear combinations. If the derailleur capacity does not match the gear sizes on a bike, the chain may appear to fail either the "too long" or the "too short" test.

Chain Size

1. Pitch
   
   • Distance between rollers (1/2" on all modern bicycle chains)
   • Measuring a bicycle chain's pitch can be used to identify chain wear and flag the need for a replacement chain and/or cogs and chainrings
2. Width
   
   • Internal width where the sprocket teeth fit in A.K.A. distance between the two inner plates
   • Related to the maximum thickness of a sprocket that can realistically engage with the chain and that dictates the thickness of gears which in turn is specific to the type of bike. Typical sprocket thicknesses range from 1.7mm to 2mm.
     
   • Comes in two typical widths:
     
     • 1/8": standard width of a BMX bike chain and also on most single-speed bikes
     • 3/32": standard width for all modern multi-speed bikes. These chains are commonly referred to as "derailleur" chains

Chain manufacturers typically use the number of gears as the way to differentiate chains for a 10 speed bike vs a thicker chain for a 9 speed bicycle. You'll commonly see "10s" or "9s" in the listings rather than referring to the actual measured external width, although often this information is available as well.

How to determine the bicycle chain size you need:

1. Chain Internal Width: 3/32" for derailleur bikes
2. Chain External Width: i.e., 10s
3. Chain Pitch: Typically 1/2"
4. Sprocket Shape: Shimano v.s. SRAM

How to check for chain wear

Measure the chain by placing the ruler's "0" mark directly above the center of one of your chain pins. Now count 12 complete links. A complete link equals 1 inner and 1 outer (apprx. 1"). A rivet on a new chain should line up exactly with the 12 inch mark using this method.

• Wear Indicators
  
  • If the rivet is less than 1/16" past the mark, your chain is okay
  • If it's between 1/16" and 1/8" past the mark, you'll likely need a new chain, but your sprockets should be okay
  • If it's more than 1/8" past the mark, you'll have to replace both the chain and the rear sprockets
    
    • Why? Because the rear sprockets generally wear with the chain. While the chain is "stretching," the gap between the teeth on your sprockets also gets wider and wider. This causes the chain to ride up over the teeth and slip while pedaling under pressure.

How to calculate the right chain length

1. Use the old chain length
   
   • Before removing the old chain, check the bike for acceptable length. If there is sag (too long), then subtract 2 chain rivets. If too short, ("S" bend as chain passes through the pulley wheels when it's on the largest chainring and second largest rear cog)
2. Measure off the largest cog and chainring
   
   • Remove the old chain. Shift into the front largest chainring and smallest rear cog. Wrap the chain around the largest cog and chainring but do NOT run the chain through the rear derailleur. Bring the ends together on the front chainring until they can be just connected, then add one extra link to the length (should = 1").
3. Chain sizing by equation

How to break a "standard" chain

1. Check to make sure there isn't a quick-release link.
   If there is no master link and is not a Shimano chain, the chain is known as a "standard" chain. It is a disappearing breed as bikes now have more rear cogs and correspondingly narrow chains.
   
2. Take the chain tool and back out the pin by turning the handle counterclockwise. The outer cradle is used to connect/disconnect chains. The inner cradle loosens stiff links. Place one of the chain links on the outer cradle.
3. Tighten the handle clockwise until the chain tool's pin connects with the end of your chain pin. Continue tightening until the handle starts showing resistance. Take off the chain tool. There should be about 1mm or so of rivet protruding.
   
4. Twist and pull to disconnect the chain.
5. Watch the derailleur. It will swing back. Carefully note how the chain was routed through it.

How to install a new chain

1. Determine chain length
2. Shift to smallest front and smallest rear cog (to have max slack to work with)
3. Make sure the pin is pointing away from the bike before you start
4. Starting with the bottom pulley, guide the chain up and through the rear derailleur, over the smallest rear cog and through the front derailleur. Bring the chain ends together around the smallest front chainring.
   
5. Push the ends together, snapping the end link over the little stub of pin. Use the chain tool to push the pin back in until it's flush at the other end.
   
6. The process of re-connecting the chain has caused the chain links to compress together, making a stiff link. To fix this, use the inner slot on the chain tool and tighten it just barely, about a quarter of a turn.

NOTE: Most chain failure is due to one of the pins being improperly installed.

Shimano ChainShimano chains have a special connecting pin called a "subpin" to ensure a stronger chain connection. The 7 and 8 speed chains use a black connecting rivet and 9 speeds use a silver connecting rivet. When disconnecting a Shimano chain, be sure to select a chain rivet identical to adjacent rivets. Do not select a previously installed connecting rivet or a rivet immediately adjacent to a connecting rivet.

Connecting a Shimano Chain

1. Remove any extra links, pushing the appropriate rivet completely out
2. Line up the chain ends
3. Push the subpin in with your fingers, pointed end in first. It will go in about halfway
4. With the chain tool, push the subpin through until there is only as much left protruding at the tail end as the other rivets in the chain.
5. Break off the leading half of the subpin with a pair of pliers.
   
6. The chain should move freely. If it does not, flex it back and forth to relieve the stiff link.

Master Links (below covers 2 common types, both of which only need pliers to connect/disconnect)

• Type #1: Found on BMX and single-speed bicycles. There are 3 parts: one link plate with two chain pins attached, a plate with no chain pins that slide on the other side, and a clip that holds the link together once installed.
  

Disconnecting Type #1:

Place the jaws of your pliers on the chain pin and the other jaw on the other open end of the clip. Then squeeze your pliers until the clip pops off. Then you can remove the outer plate and slide out the rest of the link.

Reconnecting Type #1:

Slide in the link with the chain pins, place the outer plate on the other side, and then put the clip back in place. This time, place one jaw of your pliers on the closed end of the clip, and the other jaw on the opposing chain pin. Then squeeze them together until the clip snaps into place.

• Type #2: Found on derailleur chains. There are only 2 parts: each of the two plates are identical and each has a chain pin on one end.

Disconnect Type #2:

Place pliers on opposing ends of the link. and then squeeze the pliers together until you hear a click. Now you can slide both links out.

Reconnect Type #2:

Slide both ends of the link together and then rotate your chain on the bike until the quick release is on the top and the pedal is facing forward. With both wheels on the ground, compress your brakes so your bike doesn't move. Then step down on the pedal. The links should snap into place.

How to Clean your Chain

1. Shift the chain to the smallest rear sprocket.
   
2. Wipe the chain clean with a solvent soaked rag, by holding the chain still at the rear derailleur cage while firmly wiping the lower run of the chain. Then, move the chain backwards and wipe again until you've wiped the entire length of chain.
3. Wipe between the rear sprockets, cogs, and jockey pulleys
4. Use a rag dipped in water to wash off the solvent.

How to Lube your Chain

1. Shift to the middle sprocket in the front and rear. Remember, oil does a good job of spreading itself so do not try to over-apply the lubricant.
2. Run the chain backwards while dropping oil down both sides of the rollers.
3. Shift through all the gears to spread the lube evenly through the drivetrain
4. Drop a few drops of lube into the cassette
5. Use a rag to wipe off any excess oil

How to troubleshoot a squeaky chain:
(Squeaking is caused by dry or rusted surfaces inside the chain rubbing on each other)

1. Wipe down and lubricate the chain
2. If the squeak does not go away, replace the chain.
   If the initial remedy does not work, the chain is too dry inside and probably rusted as well. Chains seldom heal from this condition)