SPROCKETS

Sprockets need to be though, hard-wearing and light. Front (engine) sprockets are almost always steel – it's cheap and strong. And since it's hidden behind a cover, it doesn't need to look particularly flash. Rear sprockets can be steel, but the performance option is aluminum alloy. The larger rear sprockets rust and look hideous after a few thousand miles. Aluminum sprockets do wear quicker than steel though, so the mile – munchers and penny – pinchers will have to do with a brown scabby rear. Fans of bling could have magnesium or titanium sprockets made up, but that's bordering on madness.

WHY A CHAIN ?

A chain isn't the only way to drive your rear wheel. The earliest bikes used leather belts, and modern designs use shafts, belts or gears, Chains have remained top choice for performance bikes though, because they're cheap, light and efficient. Shaft drive is heavy, and absorbs more power than a chain. The action of the shaft also affects suspension movement, and the gyroscopic effect of a heavy, rapidly spinning shaft can also affect handling.

Belt drives is used on lighter commuter machines, as well as Buells. There is a limit to the maximum power a belt can take, though, and they are very wide, making swingarm and wheel design tricky. Changing gearing is also an expensive job – the belt runs on pulleys which are more pricey than sprockets.

There have been some bikes – old Nortons, Heskeths, MZs and the like – with enclosed final drive chains. These have a sealed case around the chain, which runs in an oil bath. The chain lasts virtually for ever, but it is hideously unstylish.

Like the chain itself, chain maintenance is simple in essence. Keep it clean, lubricated and adjusted and it will last for thousands of miles. But in real biking life, that's as easy as giving up fags or choc digestives. If you're a real mileage junky, then there are plenty of automatic oiling devices out there – the Scottoiler is probably the most famous. In essence, these contraptions have an oil reservoir and some tubing, and they drip a constant flow of oil onto the rear sprocket. The flow of oil is controlled either by a vacuum feed form the engine, or an electronic switch, or a motion sensor. The oil deeps the chain lubricated and clean, and the flow can often be turned up to deal with bad weather. Chain adjustment varies according to our bike, so check the owner's manual. The main points to check are that each side is equally adjusted, and there is the correct amount of slack in the chain – again, check the manual or ask your dealer. Make sure the rear spindle id properly tightened up, and any split pins or R-clips are back in place, and you're set.

<<Previous page