Motorcycle Transmission Types

Pushing the Power to the Road

A motorcycle transmission isn't hard to understand. it doesn't take a genius to realize that the engine is producing a turning shaft which needs to be link to the back wheel. This is the key role for the bike transmission. For this page I just want to focus on the end part.

As the engine makes r.p.m (turns per minute) the motorcycle transmission links those turns to a better ratio (gear box) so that the engine power becomes usable to power the back wheel. The clutch will allow the rider to disengage the selected gear and move it to a new one (or neutral). Selected into a gear the engine power is directed towards the wheel via the final drive.

Drive belts
A drive belt is the oldest method for powering a bike. Belts have a very good track record. In the old days belts were made of leather but now they are made of high quality rubber. A belt will last longer than a chain, has hardly any stretch, rides very smooth and has very low maintenance.

Replace every 4500 miles / 8000 km. Inspect the quality of the the belt (play of ½ inch / 1,5cm play on the top strand. After replacement adjust the belt after its first few hundred miles / kms. Check that the sprocket is smooth and not slowly busting up your drive belt. That's all.

Drive shafts
A drive shaft is the same principle as on a car however the shaft is enclosed on a motorcycle. A drive shaft on a motorcycle is heavy and expensive but is low maintenance and gives a smooth ride. Extra disadvantage is that the turning of the shaft influences the riding aspects of the motorcycle.

Drive Chains
Chains have become the major form of powering bikes world wide and for a reason. A chain will only lose 1% of it's power when transferring from the engine to the wheel, they are cheap and durable in extreme conditions. Having this said chains are noisy, not super smooth in ride and need good maintenance to be effective. Also see my section on chains!

Motorcycle transmissions are split into three types: the drive belts, the drive shafts, the drive chains.

The speed that the crankshaft spins around is expressed in RPM's (revolutions per minute)

A unitized transmission refers to a transmission that is an integral part of the engine's bottom end (aka unit transmission)

The primary drive is the chain connecting the transmission to the crankshaft. Used in Harley Davidson motorcycles.

Transmission maintenance should be a regular part of your service schedule - check, adjust and lubricate chain - check, adjust and lubricate clutch cable - check drive belts on such bikes

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