While various systems have been trialled over the years and adopted with some success (think BMW’s shaft-drive and other using belt drive), the good old chain is by far the most common way of transferring the torque output of the bike’s gearbox to the rear wheel and on to the road.
Chains are fairly cheap, easy to make and use, and pretty robust – as long as you look after them. This means not only cleaning and lubricating them regularly but also making sure their tension is correct.
If a chain is too tight, it can put undue strain on the bike’s transmission systems. Too loose and it can flail around, cause excessive wear and even run the risk of breaking.
Thankfully, looking after your motorcycle chain isn’t tricky. It's a simple bit of maintenance that's easily done by most owners, as it requires only basic tools and rudimentary skills. Looking after a chain is part of the upkeep of your bike, so you’ll need to do it regularly - unless you’re a big BMW owner.
Here’s how to look after your chain.
The first job is the check your bike’s chain tension. To do this, you need to measure the distance between a fixed point on the chain and a fixed point on the bike, starting with the chain hanging down in its relaxed state.
With the ruler in the same place, push the chain up as far as it will go without straining it. The difference between the two is your chain sag. You now need to compare this with the figures that will be specified in the handbook – there will be a minimum and a maximum.
If your measurement is within the stated tolerance in the handbook, all is good. If not though, you’ll need to adjust your tension by moving the back wheel backwards (increase tension/reduce gap) or forwards (reduce tension/increase gap).
To adjust the chain tension, the first thing you need to do to move the wheel is to release the rear-wheel spindle nut. This will be pretty tight, so you may need a breaker bar (a long-handled socket drive) or an extension bar on a shorter socket handle.
Release the torque on the nut enough so that the wheel can move, but not too freely – it needs to stay in position when you move it.
Now release the locking nut on the adjusters on each side of the swingarm. Yours may look like this, or they may be in front of the rear-wheel spindle.
With the locking nut released, you can now rotate the adjusting nut to re-position the rear wheel and change the chain tension. In this case, rotating the nut clockwise will move the wheel closer to the engine and counter-clockwise, farther away.
However, for adjusters in front of the wheel spindle, it will be the opposite way round. If you need to move the wheel away from the transmission on a bike with adjusters behind the wheel, you may need to physically pull it, then reposition it with the adjusters in the right place.
On some bikes with single-sided swingarms, you may need to rotate an eccentric adjuster to change the wheel’s position – the owner’s handbook should show how to do this.
Re-measure the chain tension after you have made small adjustments. Keep going until the figure reads as roughly in the middle of the range specified in the owner’s manual or workshop manual.
Once you have made sure the chain tension is correct, you need to check that the rear wheel is in line with the rest of the bike, otherwise, you will find the bike steers from the rear and you can also increase chain and sprocket wear if the chain isn’t running true on the sprocket.
There will be marks on the sliding section of the rear-wheel spindle mount on each side of the swingarm – check that there are in the same position.
Once you’re happy the rear wheel is aligned correctly, tighten the locking nuts on the adjusters so that the rear wheel can’t move. The tightening torque will be in the owner’s manual – we’re illustrating it here with a spanner, but you’d use a torque wrench to get this right.
Now it’s time to tighten the nut on the wheel spindle. Again, we’re illustrating it with a ratchet handle, but you should use a torque wrench to make sure you tighten it with the correct force.
This would be specified in the owner’s or workshop manual and on our Royal Enfield Himalaya (pictures), the figure is 70Nm or 52lb·ft. Finally, make a last check on the tension and the alignment to make sure nothing has moved as you tightened the rear wheel.
While you should check the chain tension regularly – such as when you clean the bike or check the tyre pressures – you won’t need to adjust it very often. This is particularly true if you’re cleaning and lubing it properly.
There are differing opinions on how often you should clean and lube the chain but we like to lube it with every wash or weekly and clean it every other wash. To clean it you need to be able to spin the rear wheel – either put it on the centrestand or use a real-wheel prop or roller and coat the entire chain in a cleaner.
While many will say leave then rinse off, we generally prefer to agitate the solution and grime to get the chain as clean as possible. A brush such as this is perfect; the three sets of bristles will clean the face of the chain and the sides of the links at the same time.
You fit the brush over the chain and hold it against a fixed part of the rear swingarm. You then spin the rear wheel and the brush helps to get rid of any accumulated muck and debris as the chain passes through it. Once you have done this a few times, you can rinse with water or another blast of cleaner.
Once your chain is clean, and with the rear wheel on a roller or propped off the ground, you repeat the process with chain lube. We usually spin the rear wheel fast and apply a coating directly to the chain links then one either side, ensuring good coverage to keep the chain as wear-free as possible and eliminate any tight sports that can affect the ride, handling and wear of the chain.