The final drive is the last stage of the power transmission in a motorcycle and is the significant factor affecting the performance of the bike. If we look down to our bike’s rear wheel, we’ll probably going to see one of three things, either it will be chain and sprocket, belt and pulley or a drive shaft. Each system has its own pros and cons, but which set is best? You won’t buy a motorcycle solely on what kind of final drive it has but it’s totally worth knowing how the system differs.
The early motorcycles were all belt drive and drove by way of a tensioned leather belt running from engine’s output shaft. Nowadays we see belt drive basically in cruisers and occasional e-bikes. Compared to shaft drive and chain drive, the belt drive is smoother, cleaner, super quiet during the operation and doesn’t need any lubricant for maintenance. Belts can last exceptionally a long time, a properly maintained belt can go up to 1.5 lakhs kilometer or more or can last up to a decade and that is the reason why most cruisers specially Harley uses belt drive.
Belt drive has great life expectancy, but if it breaks on a long tour, you would have a good trouble just for the replacement of the belt as it requires removing of swing arm, also packaging is a big draw back in the belt drive and it has 11% of frictional loss in power transmission which is far more than the chain and sprocket. Moreover belt drive is not cheap, but if we consider the life and the reliability that it offers then extra money does make sense.
The drive shaft is found only in those motorcycles in which the engine is mounted longitudinally, which means the drive shaft runs parallel to the direction of the engine. Company like bmw has been using shaft drive in their motorcycles since 1923. Shaft drives are enclosed in a housing immersed in oil which protects it from rain and dirt, require low maintenance as it mostly needs only oil change in transmission housing, it doesn’t break easily, that makes it last longer and it is easy to clean.
On the other side shafts are complex, they weigh a lot and no easy gear changes. If the shafts had a breakdown, they can cost you a good amount to built and the frictional losses are far more than any of the final drive systems.
Chain and sprocket are the most common form of final drive. They are produced in masses as they are cheap to make, they are fairly durable, compact, easy to replace, offer easy gearing changes and are the most efficient means of power transmission. That is the reason most of the super bikes has chain drives.
But every tech has its drawbacks. Despite being economical they require regular cleaning and lubrication, they wear out much faster than belt drive and they are a bit noisier. You have to intermittently adjust the chain to maintain its proper tension, the sprockets are also subjected to wear and need to be replaced from time to time.
So, to conclude which is the best and why?
That depends upon the purpose for which you are buying the motorcycle.
If you want to cover long distances and simultaneously want your motorbike to be clean and shining without getting your hands dirty. Belt drive is the best option to go for. Harley Davidson Sportster, BMW F800 GT, Kawasaki EX250-C uses belt drive.
If you are planning to cross states and also want a low maintenance touring bike in which you don’t have to stop now and then to adjust and lubricate the chains after each 300-400 kms, you should go for the shaft driven motorcycles. That is the reason bikes like Honda Goldwing, BMW K 1600 GT, Kawasaki Concours uses shaft to spin their wheels.
If you are applying for races or stunts with your bikes, you should go with chain drives as these are quiet affordable with best design flexibility strength. Super bikes like Kawasaki Ninja H2 SX, Ducati Penigale V4 S, BMW S1000 RR uses chain drive for high speed and dynamic ride. Chain drives are also used very widely in the economic motorbikes.