Drivers who use high-performance racing motorcycles are being killed at a rate nearly four times higher than those who navigate all other types of bikes, finds a U.S. study.

The Insurance Institute for Highway Safety (IIHS), which conducted the research, also found that the popular "supersport" motorcycles had the worst overall insurance losses.

"Supersport motorcycles are indeed nimble and quick, but they also can be deadly," Anne McCartt, senior vice-president for research at IIHS, said in a press release.

"These bikes made up less than 10 per cent of registered motorcycles in 2005 but accounted for over 25 per cent of rider deaths. Their insurance losses were elevated, too."

The bikes are built on racing platforms and then modified for the highway before being sold to consumers.

They boast a light weight, powerful engine and are meant to be all about speed. IIHS says the bike is especially popular among riders younger than 30.

In the U.S., motorcyclist fatalities have more than doubled in the last decade, reaching 4,810 in 2006. The figure accounts for 11 per cent of total highway fatalities.

Here's a breakdown of deaths per 10,000 registered motorcycles in 2005:

• Supersport drivers: 22.5 per 10,000
• Sport and unclad sport bikes: 10.7 per 10,000
• Cruisers and standard motorcycles: 5.7 per 10,000
• Touring motorcycles: 6.5 per 10,000
• Other/unknown: 4.3 per 10,000
• Total: 7.5 per 10,000

Between 2000 and 2005, overall motorcycle driver deaths rose 59 per cent in the U.S. Meanwhile, the overall death rate climbed to 7.5 driver deaths per 10,000 from 7.1.

Only 51 per cent of drivers wear helmets certified by the U.S. Department of Transportation, compared to 71 per cent in 2000.

Motorcycle popularity

As motorcyclist deaths rise, so does the popularity of the vehicles. Between 2000 and 2005, total registrations in the U.S. climbed by 51 per cent. In the supersport category, registrations were up 83 per cent during the same time period.

Still, cruisers and standard motorcycles made up the bulk of registrations.

The IIHS found speeding and driver error to be the biggest factors in fatal crashes of supersport and sport and unclad sport bikes.

Speed was cited in 57 per cent of supersport fatal crashes in 2005. It was cited in 46 per cent of fatal sport and unclad sport motorcycle crashes.

"Supersport motorcycles have such elevated crash death rates and insurance losses because many people ride them as if they were on a racetrack," said McCartt.

"Motorcyclists presumably buy supersports and sport bikes because they want to go fast, and manufacturers are happy to oblige."

McCartt suggests capping the speed of the street-legal racing machines at the factory as a way to reduce their risk.

The supersport bikes also have the highest overall collision coverage losses among 2002 to 2006 model bikes. The figure is almost four times higher than touring motorcycles and six times higher than cruisers.

The bikes are also popular targets among thieves, stolen at a rate seven times higher than the average for all 2002 to 2006 motorcycles.

"These bikes own the field when it comes to elevated death rates and collision losses. They also hold the distinction of being the most frequently stolen motorcycle," says Kim Hazelbaker, senior vice president at the Highway Loss Data Institute.

"We found a strong correlation between motorcycle class and insurance losses, with supersports showing up time and again as having far higher losses than other types of motorcycles."