CHICAGO - A polyurethane used in automobile suspension systems has replaced a metal shock absorber in a new cross country bicycle. Klein Bicycle Corp. of Chehalis, Wash., is using BASF Corp.'s Elastocell microcellular PU in the suspension shock cylinder of its Mantra all-terrain racing bicycle. The $4,000 bike is currently being ridden by Klein's professional racing team and will be on the market in June.
The Mantra's single shock cylinder contains two PU springs weighing 42 grams and 47 grams that can be compressed to 35 percent of their original height. The springs are in a canister and around an aluminum shaft.
Darrell W. Voss, vice president of operations at Klein, said the low-maintenance shock cylinder replaces a metal part that weighs five times as much, a major consideration on a high-end bicycle. All-terrain bikes have mostly used metal air cylinders that are heavier and prone to leak around the seals.
``We had previously tried open and closed cell foams without much success,'' Voss said. Then we came across the BASF material in an auto application and backtracked from there to develop our springs.''
Voss said the suspension system provides better cushioning and less bounce to the rider. The PU absorbs shock but has a slower spring back, which dampens jolts, he said.
BASF said the material can be tailored to different shock absorbing applications by changing the density of its components.
Voss said Klein will use PU shock cylinders on less-expensive models starting in 1996 and expects competitors to follow.