How to provide the same strength yet be ultra-low weight – the new inner tube for mountain bikes from Schwalbe takes on this challenge. The company, the market leader in Europe for bicycle tires and inner tubes, has worked with BASF to develop a new thermoplastic material. It is based on the thermoplastic polyurethane (TPU) Elastollan by BASF. The excellent mechanical properties of this material mean that the wall thickness could be considerably reduced. This gives the eye-catching blue Evo Tube an important advantage over butyl-based inner tubes: the weight has been reduced by as much as 65% compared with a standard 29-inch tube; depending on the size of the tire, the Evo Tube weighs between 68 and 76 grams. According to Schwalbe, the tube will be in stores from December 2015.

The thermoplastic polyurethane from BASF is remarkable for its many useful material characteristics. It is particularly resistant to abrasion and wear and therefore really 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. An interesting 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. “Thanks to our extensive portfolio of suitable types of Elastollan, we were able to find the perfect combination of materials to make the new Evo Tube,” explains Sascha Mattfeld, from TPU Sales at BASF.

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 Centre. 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,” adds 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 blow molded.