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Motorcycle Factors: Motorcycle Design Table of ContentsHomenhtsa

Introduction to Motorcycles

Motorcycle Design


Vehicle Modifications


Lane Use


The design of motorcycles has made them increasingly more capable and specialized, and generally reflects a greater emphasis on safety.

In general, motorcycle design has yielded steady safety improvements. The motorcycles of today are better in virtually every significant safety area than those of just two decades ago.

Current motorcycles have better brakes, greater stability, more responsive steering, more effective controls, improved ergonomics for better control and reduced fatigue, and improved reliability in all systems than those of even a decade ago.

The acceleration and top speed of the most powerful models (mostly sportbikes) have increased continually. The effect of these performance increases on safety is currently unknown.

Tires, which are particularly crucial components on a two-wheeled vehicle, have advanced significantly and have contributed much to vehicle performance, reliability, and safety. Modern tires are more durable, offer better traction for turning and stopping, and have contributed to significantly improving stability compared with their counterparts of the 1970s.

Some motorcycles have hand and foot controls that can be adjusted to accommodate various riders with larger or smaller than average hands and feet, thereby increasing the riders’ control of these motorcycles.

Brakes are often significantly more powerful and can have an antilock braking system and/or linked front and rear application.

Lack of rider protection is a characteristic of all motorcycles. Research into devices to reduce rider injuries in crashes is ongoing. Because of the lack of coupling between motorcycle and rider (which would create an additional hazard), motorcycle-mounted rider protection systems have significant limitations (Ouellet, 1990; see Personal Protective Equipment, page 27).

• Leg protectors have been devised and studied in the United States and internationally, but the results have been mixed thus far. There is no widespread agreement that they provide additional protection, and they may pose safety drawbacks.

• Motorcycle airbags have been under study for 30 years both as vehicle equipment and as a part of the rider’s apparel. At this time, the benefits and risks, such as undesired deployment, are still under investigation (Iijima, 1998).

The evolution and specialization of street motorcycles to meet specific requirements of the market have created some design features that raise safety issues and suggest further research.

• Studies of earlier types of machines have shown that fuel tanks that rise abruptly from the saddle immediately in front of the rider contribute to severe pelvic injuries in frontal impacts (Ouellet, 1981). Most current sportbike tanks have a similar style and are likely to present a similar injury mechanism.

• Some cruiser and touring motorcycles place components, such as instruments and controls, atop the fuel tank. These designs may increase uro-genital injuries during crashes.

• Motorcyclists complain that windshields that extend through a rider’s line of sight impede vision under certain conditions, including rain and nighttime.

• Although tubeless tires significantly reduce the likelihood of a blowout and resulting loss of control, tube-type tires are still fitted to many cruiser models in order to use wire-spoke wheels for appearance reasons. However, alter-native wire-spoke wheel designs exist that may be used with tubeless tires. Wire wheels may also be sealed for use with tubeless tires. The Hurt Report listed puncture flats as the primary motorcycle vehicle failure leading to crashes.

• Emphasis on styling simplicity, the search for weight reduction, and lack of space often dictates a single-bulb taillight. The failure of either the taillight or brake-light filament can leave the motorcyclist without rear lighting.


We want to understand the effects of current motorcycle design on safety. Specific issues that must be addressed include:

• The effects of rapid acceleration and high top speeds

• The run-flat performance of motorcycle tires

• Injury mechanisms of current designs

As with other vehicles, fashion is a significant factor in motorcycle design. However, there may be some safety consequences that are not desirable. Safety should not be sacrificed for the sake of fashion.

More motorcycles should offer control adjustments to accommodate riders who are larger or smaller than average.


Research is needed to learn about the effects of current motorcycle design and performance on safety.

Although some issues raised here concerning motorcycle design await research and technology for solutions, others—such as vision restrictions and tube-type tires—can be addressed with current technology as research results dictate.


• Conduct research to determine how current motorcycle designs affect crash and injury causation.

• Implement the use of available tire and wheel technology and explore technology, such as run-flat tires, to reduce frequency of loss-of-control crashes caused by puncture flats.

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