Motorcycle Transmission Types

Pushing Power to the Road

A motorcycle transmission isn’t hard to understand, nor does it take a genius to realize that the engine is producing a turning shaft that needs to be linked to the back wheel. This is the key role for the bike transmission. For this article we’ll focus on that last part.

As the engine makes revolutions per minute the motorcycle transmission links those turns to a gear box so that the engine power becomes usable to power the back wheel. The clutch allows the rider to disengage the selected gear and move it to a new one, or to neutral. Once locked into a gear, the engine power is directed towards the wheel via the final drive.

Motorcycle Transmission Introduction

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 is preferable for a few reasons:

  • it lasts longer than a chain
  • hardly any stretch
  • rides very smooth
  • very low maintenance

Replace the belt about every 4500 miles (8000 km). Inspect the quality of the the belt (play of ½ inch on the top strand). After replacement, adjust the belt after its first few hundred miles. Check that the sprocket is smooth and not slowly busting up your drive belt and you are good to go!

Drive shafts
A drive shaft works on the same principle as 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. Another 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 – for good reason. A chain will only lose 1% of it’s power when transferring from the engine to the wheel. Also, they are cheap and durable in extreme conditions. Having said that, chains are noisy, don’t provide a super smooth ride, and need good maintenance to be effective.

Motorcycle Transmission Tips

  1. Motorcycle transmissions are split into three types: the drive belts, the drive shafts, the drive chains.
  2. The speed that the crankshaft spins around is expressed in RPM’s (revolutions per minute)
  3. A unitized transmission refers to a transmission that is an integral part of the engine’s bottom end (aka unit transmission)
  4. The primary drive is the chain connecting the transmission to the crankshaft.
  5. 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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