Schwalbe, the leading brand in Europe for bicycle tires and inner tubes, has developed a inner tube for mountain bikes made from a novel material that is based on BASF’s (Ludwigshafen, Germany) thermoplastic polyurethane (TPU), Elastollan. The brand is owned by the German company Ralf Bohle GmbH, a third-generation family-owned company, who collaborated with BASF on the development of the new material. This resulted in the new electric-blue Evo Tube, an inner tube offering the same strength as butyl-based inner tubes, but with a considerably reduced wall thickness. Due to the excellent mechanical properties of the new material, the weight of the Evo Tube is as much as 65% less than that of a standard 29-inch tube; depending on the size of the tire, the new inner tube weighs between 68 and 76 grams. According to Schwalbe, the tube will be in stores from December 2015.
The new material is particularly resistant to abrasion and wear and therefore very long-lasting. Furthermore, an inner tube made from this plastic can withstand a very high level of continuous load and—despite its greatly reduced wall thickness—maintain a constant air pressure over long periods. A really clever feature of the solution that was developed with Schwalbe is that the tube, valve base and valve stem are all made from materials based on Elastollan. This simplifies the production process and also allows the product to be easily recycled.
BASF helped Schwalbe over a period of two years with selecting the material, carrying out production trials and providing ready-made components from BASF's own Application Engineering Center. During the work on the project, extensive mechanical stress tests were carried out, especially with regard to temperature and pressure resistance and gas permeability.
"Our close partnership with BASF was focused and constructive in every way: we received intensive support and advice and were flexibly supplied with sample components throughout the whole period of the project," said Marcus Lambertz, the Evo Tube Product Manager at Schwalbe. "We are already working on developing more versions based on the same material."
The thermoplastic polyurethane from BASF also has a wide range of possible applications in other industries and sectors, for example in the automotive industry or in mechanical engineering and medical engineering. The synthetic material can also be processed in various different ways: among other things, Elastollan can be injection molded, extruded or blowmolded.