Dr. Frank Jamerson sent me the following comment on the two articles critical of e-bikes in the Wall Street Journal:

The article by Shai Oster (Wall Street Journal 1/19/10) on “E-Yikes! Electric Bikes Terrorize the Streets of China” emphasizes that traffic fatalities have been growing rapidly as more electric bikes are on the streets. However Oster neglected to use the more accepted way to discuss such numbers, that is on a per vehicle basis. Comparison can then be made to fatalities per vehicle caused by other vehicles to determine if the electric bike numbers are significant. Oster reports China had 2,500 fatalities in 2007 for 66 million (EBWR estimate) electric bikes on the road, thus 3.8 fatalities per 100,000 electric bikes for 2007.

Oster says China has 90,000 traffic fatalities annually, mostly from cars and trucks, with only 3% (2,500) coming from electric bikes. Vehicle population is around 30 million resulting in 300 fatalities per 100,000 vehicles. In the USA, the numbers are 40,000 fatalities for 200+ million vehicles or 20 fatalities per 100,000 vehicles. The higher number in China is understandable as car use is a recent phenomenon in China. Thus electric bikes are safer than gasoline powered vehicles on a fatality per vehicle basis.

The reason for the big difference in these numbers is that electric bikes are lighter and cars are much heavier so have more kinetic energy to dissipate in a collision. Kinetic energy is a product of mass and velocity squared. Take EB + rider weight of 200 pounds (50 pound EB + 150 pounds for rider) and speed of 20 mph. Take car weight 4,000 pounds, with driver, and comparable speed 20 mph. Calculation shows that the kinetic energy of the car is 20 times higher than the bike with rider, from the mass difference since speed is same. Cars can travel faster of course and at 30 mph car kinetic energy is 40 times higher than the EB. Thus car collisions will cause more damage to vehicles and passengers when compared to a much lighter bike that has much less kinetic energy to dissipate in a collision. This is confirmed with the statistics on fatalities, as calculated on a per vehicle basis.

Frank Jamerson, Ph.D.
Naples, FL
Electric Bikes Worldwide Reports
www.ebwr.com
Posted by: Bill Moore