Edited by Jean M. Hoffman

Engelbert Brenter invented the sitting ski in 1949, which became known as the ski-bob during the 1960s. In the mid-1990s, the sport experienced a renaissance as Brenter's grandson, Bernd-Eric Brenter, revamped and modernized the old design as the Snowbike.

Engelbert Brenter invented the sitting ski in 1949, which became known as the ski-bob during the 1960s. In the mid-1990s, the sport experienced a renaissance as Brenter's grandson, Bernd-Eric Brenter, revamped and modernized the old design as the Snowbike.


Components that secure and steer Snowbikes from Brenter in Austria are made from an impactresistant Zytel ST801 polyamide. The parts include a hinge that transfers handlebar movements to the front runner for steering and brackets for attaching skis to the frame. Snowbikes resemble bicycles but with two runners instead of wheels. Riders wear two short skis on their feet for stability through steep curves.

"The demands put on Snowbike components are extreme," says Bernd-Eric Brenter. "They must withstand UV exposure at 3,000 m (9,842 ft) and impacts at temperatures ranging from 20°C (68°F) in the hire-shops to subzero conditions on the slopes."

Zytel ST801 is an unreinforced polyamide 66 from DuPont Engineering Polymers, Wilmington, Del. It retains mechanical properties at temperatures down to 40°C (40°F) and thus, says Brenter, is an established material for winter-sports and other gear that must resist blows and impacts at temperature extremes. "Further, the material is weatherproof, scratch resistance, and provides an attractive surface finish."

The polyamide processes easily. This was also a decisive factor in material selection, says Brenter. "It is highly suited for the thick-walled, injection-molded parts in our Snowbikes. There is negligible warpage during cooling, and the risk of material deficiencies caused by voids and sink marks is also low."

"Zytel polyamide was the material of choice from the start, according to Peter Kulischek of Biesterfeld Interowa an Austrian distributor for DuPont engineering resins, the only question was whether a reinforced or unreinforced grade would provide enough strength and stability. "Tests showed the unreinforced grade fully met the Snowbike's challenging requirements," says Kulischek.

MAKE CONTACT
Brenter 43-6272-7777, www.snowbike.com
DuPont Engineering Polymers (800) 441-0575.
plastics.dupont.com