Most motorcycles use a chain to send power from the gearbox to the rear wheel. It is efficient, light and easy to change for different gearing, but it needs regular attention. A neglected chain wears quickly, wastes power and in rare cases can break.
Types of chain
Standard (non-sealed) chains have no seals between the plates. They have the least friction and are used on some small bikes and in racing, but they wear quickly and need frequent lubrication.
O-ring chains have rubber rings that seal grease inside the pins and bushings. They last much longer than standard chains and are common on road bikes.
X-ring and Z-ring chains (and other variants by different makers) use seals with different cross-sections that reduce friction while keeping the lubricant in. They usually last longest and cost more.
Chains are identified by their size, such as 520, 525 or 530, which must match your sprockets. Use the size and type specified for your bike.
Cleaning and lubrication
Clean the chain every few hundred miles, and after riding in rain or dirt. Use a chain cleaner or kerosene that is safe for O-rings, a soft brush, and a rag. Avoid gasoline, aggressive solvents and high-pressure washers, which damage the seals.
Lubricate when the chain is clean and slightly warm, applying lube to the inner run so it spreads as the chain turns. Let it set before riding, wipe off the excess, and keep it off the tire and brake disc.
Adjusting tension
Your manual specifies the slack, usually measured as the vertical movement at the midpoint of the lower run, often around 20 to 40 mm (about 1 to 1.5 inches). Check it with the bike in the position the manual describes and at several points, since chains wear unevenly. Adjust using the axle adjusters, keeping both sides equal to keep the rear wheel aligned, then tighten the axle nut to the specified torque.
When to replace
Replace the chain when it reaches the wear limit (measured by stretch), shows tight spots or kinks, or can be pulled away from the rear sprocket noticeably. Sprockets should normally be replaced at the same time: hooked or pointed teeth mean they are worn, and a new chain on old sprockets wears out quickly.
Alternatives
Some bikes use belt drives (common on Harley-Davidson and some scooters) or shaft drives (BMW touring bikes, many tourers), which need much less maintenance. For everything else, see the rest of your bike’s servicing; for related noises, troubleshooting common motorbike problems.
