By Johan Bornman 

Chain life is a function of hygiene.

Chain drives are among the most efficient means of power transmission known, and modern bicycles use a 'roller chain' to connect the cranks to the rear wheel.

Although the modern bicycle roller-chain has a pitch of 1 double-link per inch, they come in two basic widths, being 1/8 inch chain for most single-speed and internally geared bicycles, and 3/32 inch chain for derailleur equipped bicycles (that have more than 3 speeds). Chains for derailleur applications also come in various external widths, as especially 10 speed (road) clusters use chain with thinner side plates and flush rivets. Older, non-derailleur chains are broken at the masterlink, whilst modern type chains can be broken at any point along their length.

The bicycle chain has a simple function: it transfers torque from the chainwheel to the cassette. It’s probably the filthiest part on a bicycle, and – consequently - the only part we actively avoid. For more than a century, inventors have been attempting to replace it with other devices, and yet the humble, filthy chain remains.

The anatomy of a chain is simple. It basically comprises of:
• link pins (‘pins’ for short), the short rods that push in and out in order to “break” the chain,
• sideplates (two types if you want to be pedantic – ‘inner’ and ‘outer’), and
• rollers, that meshes the chain with sprocket - cogs.
 
All of these components are made of hardened steel designed to withstand wear from articulation under tension. Bending (“articulating”) the chain is easy, but under the tremendous tension placed on it by pedalling, massive friction exists between the pins and sideplates. Add some fine grit between them, and you’ll understand what causes a chain to actually wear.

Riding with a chain past its prime is expensive, as - apart from further damaging the chain itself - it eats sprocket and cassettes. Changing your chain at just the right time saves you money (in extending the life of the cassette and chainwheel), however, change it too soon, and you'll waste money.

The chain is invariably coated with oil that readily traps grit. The oil is black because of a tiny amount of steel worn from the chain. (A small amount quickly dies a lot of oil black). This is a good sign as it means the oil is mobile, i.e. flows back in after being squeezed out of the pin / sideplate interface during a stress cycle.

Interestingly, wax based lubricants are not mobile and once forced out of an interface it remains ‘out’, and no longer transports worn steel particles and grit. The upside, which manufacturers often punt, is that the chain stays clean, but what they don’t tell you is that a clean chain is a chain without lubrication!

In many ways the chain is the most vulnerable component on the bike – out in the open, having to process destructive grit under angular(often) load stress - being the component that takes the most punishment. From time to time we shift carelessly and the chain protests by derailing, and ‘jumps’ off the chainring. In spite of their durability, chains do have a limited life. Contrary to bike shop lore - however - its lifespan is not determined by the distance ridden since new, but by hygiene. The cleaner you keep your chain, the longer it lasts.

Its dirt that does the most damage deep inside the chain’s joint between the two sideplates, and on the pin. It's also this grit that is the most difficult to clean out. Wiping your chain with a rag (or brushing with degreaser) does almost nothing, being purely cosmetic.

To clean a chain well, it really needs a good soaking with agitation in solvent, preferably off the bike. Quick- links make it easy to remove the chain each time you clean it.  I also like those gadgets that clip onto the chain and roll it through a couple of brushes and through a batch of degreasers. Alas, they’re expensive and don’t last all that long.

The best method is to remove the chain and immerse it in a bottle of solvent. (A two-litre bottle with 500ml of paraffin works best.) Close the bottle and shake it. If you think the chain is clean, fish it out with a piece of wire and give it a second cleaning with some water-based degreaser. Flush it with water until the run-off runs clear. Refit it ,and oil it by dripping a drop of oil on every second link (onto the roller). Don’t bother trying to oil the sideplates, they’ll get coated with oil soon enough.

(Note: decant and re-use the paraffin, discarding only the bit at the bottom containing the collected grit.)

To optimise the lifespan of your chain, you should clean it after every ride.  Avoid re-oiling it between washes, as fresh oil on a dirty chain does a great job of transporting grit (grinding paste) to the inside of the chain, damaging both the pins and the sideplates.

A chain that looks dry does not necessarily need oil. Oil on the outside does very little for a chain and it’s the oil on the inside that matters. A trained ear will quickly distinguish between a chain that looks dry, and one that actually is dry. Sometimes a chain will look like it needs more oil, yet it’ll run quietly – this means there is still enough oil inside to lubricate the moving parts and flow back into the interface each time the tension is released at the chain’s return cycle. A dry chain is noisy - it could even squeak - rather oil it (even if it is soiled).

And remember: if it ain't broke, fix it!