The chain is literally your driving force; without it you are going nowhere fast. It has to handle tremendous strength being applied against it – power and torque from the engine snap it forward when accelerating, the suspension traveling up and down constantly changes the freeplay available, heavy braking has it snatching to try to pull up a couple of hundred kilos of motorcycle and rider – all while fully exposed to the dirt, dust and water. To keep you chain at its best and improve its lifecycle, you should clean and lubricate it regularly.
The front sprocket will always show more wear than the rear as it’s smaller and in contact with the chain more often. Inspect it regularly and look for wear indicators such as chipped, broken or fish hook-like teeth and unusual shaping.
The rear sprocket is exposed to the elements more and runs the risk of being hit by dirt, grip and little stones as well as being exposed to rain water. Inspect the rear sprocket for wear the same as the front sprocket, but also sit behind the motorcycle and look for bends or twists by rotating the wheel. Especially with adventure bikes and enduro machines it sometimes happens that the rear sprocket develops a wobble.
You should also check the chain guides aren’t bent and that the wear rubbers aren’t worn out, as these protect the swingarm from damage by the chain.
Wash the worst of the dirt and grip off with a hose, then scrub the rest with a stiff-bristled brush or you can buy purpose-made chain-cleaner brushes. Personally I use some cheap toothbrushes. Make sure all the dirt and grime is removed from around the front sprocket. In some cases, and especially on adventure bikes you will need to remove the front cover. After cleaning, I usually spin the wheel around and hit the chain with water disbursement lubrication, such as WD40, which prevents any rust forming and stops links from seizing until the next ride.
At this point, the chain should be checked for adjustment and wear. Grab the chain on the rear sprocket and try to move it forwards and backwards – only minimal movement should be obvious between the chain and the sprocket teeth. Rotate it and make sure there are not tight spots or links that won’t pivot freely.
Lubricate the chain with quality purpose-appropriate chain lubrication just prior to your next ride.
When it comes time to replace any component, I always recommend replacing as a set – fitting new chains to old sprockets will greatly reduce the life of the chain. The rear sprocket may not look as worn but once you old a new sprocket up against an old one, the true wear will become obvious. Purchasing a new chain and sprockets may sound simple, but there are lots of choices out there. You’ll need to consider not just brand but also which type or material and this is also the time to decide if you wish to change the gearing – 13:50 or 14:48 can make a difference to how you get the power to the ground.
Steel sprockets are heavier than aluminum but usually last longer. However, many of the new anodized-aluminum sprockets also last well but are often more expensive. Running a quality hardened steel front sprocket with aluminum rear is very common for some motorcycles and will provide a good lifecycle, slight weight saving and excellent aesthetics. Some manufacturers new also offer ‘self-cleaning’ sprockets (mostly for Adventure-Bikes and Enduro machines) which have a small cut-out near the teeth, which allows dirt and grid to be squeezed out during rotation, increasing longevity.
You should also consider replacing the rear sprocket bolts. Many hubs have been damaged by bolts coming loose shortly after sprocket replacement. If you choose not to use new bolts and nuts, make sure you use high-strength Loctite on the threads.
But quality-brand chains - high-strength O- or X-ring chains will last longer and need less adjustment during their lifecycle.
The Don’t Do’s for Chain and SprocketsDon’t directly hit the link on a O-ring chain with a high-pressure cleaner.
Don’t clean with harsh chemicals or solvents, which can damage the rubber O-rings.
And final advice, if you like me and sometimes like to ride the dusty roads in North or Northeast Thailand you best not lubricate your motorcycle with regular chain lubrication – dust and mud will stick to it and form a grinding paste, which increases wear. I use chain lubrication for motocross bikes, it costs a bit more but my chain stays clean even if I ride the most dusty roads on the planet.