Animated superbike image courtesy of Electronic Data Systems Corporation.

Bike manufacturers have risen to the challenge of this hard-driving bunch, with design advances like featherweight composite frames and suspension systems that would rival your father's Buick. But there remains an Achilles heel: Bicycle rims, it seems, are most prone to buckling under off-road punishment.

But some material scientists, the late Frank Worzala and Terry Richard of the University of Wisconsin-Madison, are on the trail of new materials to help mountain bike rims withstand the onslaught. The duo teamed recently with TREK Bicycle Company of Waterloo, Wis., a leading mountain bike manufacturer, to explore options to improve the strength and performance of off-road rims -- without inflating the cost.

©1995 Mark Dawson/Fat Tire Fotos.

They found a good candidate in a metal-matrix composite, a blend of 80 percent aluminum and 20 percent boron carbide particles. Boron carbide is the same super-tough material the Department of Defense uses for helicopter components. "This turned out to have considerably better properties than other composites we tested," Worzala said. "It has very high strength and high modulus."

A material's modulus is essentially its stiffness. Standard aluminum rims are light weight but have a low modulus. Bolstering the aluminum rims with boron carbide roughly doubled the stiffness of standard rims, Worzala said.

The researchers are working with TREK to produce rim sections that can later be performance-tested by TREK's fleet of test riders. But another UW-Madison innovation is being adopted by the company, solving a different problem: Braking in rain-slicked conditions.

Adding a ceramic-metal composite to rim surfaces, through a plasma-coating process, produced better stopping power in wet conditions, they found. TREK recently began marketing ceramic-coated rims with improved braking, but the surfaces are brittle and crack easily. Worzala said their innovation -- adding 20 percent nickel and chrome to the ceramic -- helped the material bond more strongly to the rim. TREK is planning to market those improved rims in the near future.

Feeling cross? Check out this Team '96/Superbike puzzle at EDS.