Machine Design

A bicycle built for three

The lightweight kid carrier that attaches to the new trioBike is a vacuum-formed, five-layered structure made from coextruded sheets of Luran S and ABS from BASF Corp., Florham Park, N.J.

The trioBike pushchair was developed in cooperation with the Danish National Consumer Agency. The carrier features five-point safety belts, disc brakes, front and rear lights, and fireproof hood and seats tested for heavy metals. The seven-speed aluminum-framed bicycle has red diodes in the seat, sports double-bottom-rim tires for safe handling, and a patented control and braking system.

The trioBike, from the Danish company of the same name, recently won the SAS Scanorama Award for best Scandinavian design. The carrier also functions as a stand-alone pushchair that can hold two small children. It is outfitted with dual five-point harnesses that meet DS/EN:1888.2003 safety requirements.

The Luran S side of the coextrusion is an acrylonitrilestyrene copolymer modified with an acrylic-ester rubber (ASA). It serves as the outside layer of the thermoformed sandwich. ABS forms the hollow section which is filled with foam. The coextruded sheets are manufactured by the Vita Sheet Group and then thermoformed and foam filled by Gibo Plast. Both companies are based in Denmark.

This multilayer structure gives stability and keeps weight low. According to carrierbike creator Sammy Hessburg-Eisinger, the ease of processing, coupled with the plastic's toughness and high UV stability, were the main reasons for choosing Luran S plastic. "It was the most stable and by far the most UV-resistant of all materials tested at trioBike. Carrier-outfitted bikes inspected after one year looked as good as new. The Luran S side of the coextrusion did not show any signs of degrading," says Eisinger.

Once the kids have been dropped off at daycare or kindergarten, the pushchair dismantles with a few simple moves. The trioBike is available in Europe and will eventually come to Japan and the U.S.

BASF Corp. (800) 526-1072,
trioBike A/S, +45 36700070,

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