Chain

Image of Chain DriveThe chain is at the heart of your bike. Without it the power from your muscles cannot be converted into the rotation of your bike’s wheels. Like your own heart, you need to look after it, although it is more easily replaced if it fails.

Inspecting your chain

You should inspect your chain regularly, at least once a month and possibly more frequently if you are doing a lot of riding in chain wrecking conditions (very wet, gritty or sandy).

The easiest way to check your chain is to use a purpose made tool. There are several brands available and most will indicate whether a chain is ok, may need changing or should be replaced. The tools are relatively inexpensive but you can also check your chain for free.

Image of chain wear tool

One visual way is to change gear to your biggest chainring (front) and smallest cog (rear). Now try to tug the chain away from the chainring at the 3 o’clock position. A new chain will not easily lift. A worn chain will lift. If the lift exposes 3 or 4 teeth the chain needs replacing.

A less touchy feely way is to use a ruler. Measure 24 links of your chain, rivet to rivet. A new chain will be 12 inches. It the distance is 12 1/16th inches the chain should be replaced.

Image of Chain wear measure

If the chain becomes too worn (more than 3-4 teeth exposed or 12 1/8th inches or more) it is likely that your cassette (cogs at the rear) will also need changing. This is because chains and cassettes wear together and if the chain becomes too worn it will damage the teeth on the cassette cogs. The result will be skipping and slipping gears, even when the chain is replaced. But it is not always the case so change the chain first and take it for a test ride – you might get lucky.

My advice is to buy the tool – you can get one for very little and a check will take seconds. That way you will do it!

Looking after your chain

Be nice to your chain. Look after it and it will last longer and provide you with smooth trouble free riding. Keep it properly lubricated and don’t abuse it:

  • Buy and regularly apply the right sort of lubricant for the conditions you are riding in. For instance, a dry weather lube will soon be stripped out in wet weather and a wet weather lube will be less efficient in hot dry conditions, attracting more dirt and dust.
  • Apply the lube to the roller, not the plates, of the chain. After applying the lube back pedal whilst holding the chain in a clean, dry cloth. This will remove any excess lube from the plates of the chain, which has no positive effect and only acts as a magnet for dirt and grim.
  • Do not change gear whilst pedalling hard, in particular whilst standing on the pedals. This will put undue stress on the chain and may cause the gear to jump or jam.
  • Try to stay in gears that keep the chain as straight as possible, so avoid being in the biggest/biggest and smallest/smallest cog combinations. You will have another gear that is almost the same but which keeps the chain straighter and therefore under less strain. For instance a big/big ratio of 52/26 (2:1) is the same as the small/medium ratio of 36/18 (2:1). Basically this means that, in either combination, your wheels will rotate twice for every rotation of the pedals.

Image of Cross chain shifting

Replacing a chain

First, buy a new chain. It is generally accepted wisdom that chains should be interchangeable between brands but you need to make sure you buy one for the right number of cogs on your cassette. If you are not sure just count them. Most modern road bikes now come with 11. A few years ago it was 9 or 10. The more cogs in the cassette the narrower the gap between them and hence the narrower the chain needs to be. A size 10 chain will not work with a size 11 cassette, and so on.

Having said that brands are interchangeable I have had an instance where a new Sram chain caused skipping on my Shimano cassette. When I swapped to a new Shimano chain there was no skipping. Since then I have matched brand with brand.

You will need a chain splitting tool to push out one of the rivets from the old chain. Once the rivet is out, pull the chain free of the gears, first noting its path, especially around the jockey wheels on the rear derailleur. If you get the new chain the wrong side of a dividing support between the jockey wheels it will not turn properly. Then you will have to take the new chain off and re-thread it. Been there, done it – more than onceJ

Your new chain will have a set number of links but this is unlikely to be exactly the same as the chain you are removing. They give you extra links because each bike will need differing numbers depending on the size of the cogs and chainrings and the size of the frame. So you will probably need to shorten the chain to be the same length as the old one. You can either lay the old chain on the ground and the new one next to it to judge the length or literally count the number of links on the old chain. Personally I do the latter, firstly because the old chain will have stretched, so lining the two side by side is not exact but mainly because the new chain will pick up a load of dust and grit from the floor. I also count everything twice because if you shorten the chain too much you will need another new chain (or at least another link pin top add links back on)!

Once you are sure you have the chain the right length use the chain splitting tool to remove the relevant rivet to shorten the chain.

Re-thread the new chain being careful to get the path correct. Please note that some chains have a right way around. For instance, Shimano chains should be fitted with the plates with the chain number on facing outwards. Guide the chain over the smallest cogs so that there is the greatest amount of slack. This will make attaching the two ends easier.

To connect the two ends of the chain you will need a quick link or a special fixing rivet. A quick link can be attached by hand but the fixing rivet will require the chain tool. The fixing rivet has a pointed attachment that makes it easy to push the rivet in, to hold the two ends of the chain together. Once in position you can use the chain tool to wind the rivet in until it is even each side. Then snap the pointed guide off with a pair of pliers.

Images of Chain Links

Test the chain by rotating the pedal and clicking through the gears.

If you have threaded the chain incorrectly you will need to remove it and rethread it. If you have used a quick link you can remove the link fairly easily. If you have used a special fixing rivet you are going to have to use some finesse (unless you have a spare fixing rivet). If this is the case, to remove the chain you need to locate the fixing rivet on the chain. It will have a solid face whereas the other rivets will have a dimple in the middle. You need to push this rivet out using the chain tool BUT DO NOT push the rivet all the way through. You need it to remain in the far plate. This is quite precise so you might need to do it a little bit at a time. It is a pain but if the rivet pops out you will not get it back in (although I have been known to super glue the pointy bit back on the rivet and even keep an old pointy bit just in case).

Once the chain is free, remove it and rethread using the end that does not have the rivet sticking out. Now reattach the two ends.

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