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Hytrel thermoplastic elastomer furnishes the appropriate levels of impact and flex fatigue resistance, high and low temperature performance, and recyclability.

Stephen Moore

October 20, 2022

3 Min Read
Image courtesy of Stephen Moore

Demand for e-bikes has skyrocketed in recent years. Changing demographics, escalating urbanization, and rising interest in outdoor activities have led to a growing demand for sustainability-minded mobility. Between 2020 and 2023, more than 130 million e-bikes (using all battery technologies) are expected to be sold, and in 2023, e-bike sales are forecast. to top 40 million units worldwide.

The Light Electric Vehicle Association estimates that the US imported approximately 790,000 e-bikes in 2021, a huge leap from the nearly 450,000 e-bikes imported the year before, and roughly 250,000 imported in 2019. In 2020, e-bike sales in the United States outpaced the sale of conventional two-wheelers.

Many firms and municipalities also now support mobility solutions such as e-bikes to reduce CO2 emissions from commuters. E-bike riders and manufacturers alike benefit from DuPont Mobility & Materials’ polymer solutions. Exhibiting at K 2022 in hall 6, booth C43, the company is translating its expertise in automotive applications to this emerging market with reportedly stellar results.

“E-bike manufacturers leverage our experience to achieve goals such as lightweighting, parts consolidation, thermal management, chemical resistance, friction reduction, shock reduction, and greater sustainability. It is a fast-growing, fast-moving industry that is a joy to be involved in,” says Clément Lopez, Application Development Specialist for E-bikes & Robotics at DuPont Mobility & Materials.

In one recent project, designer Didier Biron, founder of Biron-Etudes (Dornes, France), worked with DuPont to build an airless tire concept. Lopez and the team helped to select a specific Hytrel thermoplastic elastomer (TPE) grade (HYT6356) with Shore D hardness of 60 that would provide the correct levels of impact resistance, flex fatigue resistance, high and low temperature performance, and recyclability.

The design incorporates Hytrel flanks on which a rubber tread band is adhesively bonded. These flanks were devised as two half shells that could be mounted on standard rims.

Testing by Biron confirmed that the design and material combination could bear the load/stress and meet the max acceptable (vertical) deformation. Moreover, based on frontal curb impact tests, the airless tire offers excellent impact resistance.

Biron’s airless tire can significantly reduce maintenance time and cost because it isn’t vulnerable to punctures, and the two-part design enables swift replacement without removing anti-theft screws. The new airless tire efficiency is 80% that of a conventional tire due to higher rolling resistance. Because it is intended to be used for self-service bike fleets, lower efficiency is acceptable.

“There is more to come from DuPont in terms of solutions for e-bikes,” adds Lopez. “In addition to the tires, we are also focusing on the frame and the saddle. We are looking at a fully injection-molded frame as well as the use of foamed Hytrel, potentially our Eco B bio-based product, in the saddle to replace thermoset polyurethane.”

Hytrel can be foamed using a supercritical fluid (SCF) foaming process using CO2 and N2 gases to achieve 15% greater resilience and 20% less weight than polyurethane, which requires a chemical foaming agent.

K 2022 runs through Oct. 26 at Messe Düsseldorf in Düsseldorf, Germany.

About the Author(s)

Stephen Moore

Stephen has been with PlasticsToday and its preceding publications Modern Plastics and Injection Molding since 1992, throughout this time based in the Asia Pacific region, including stints in Japan, Australia, and his current location Singapore. His current beat focuses on automotive. Stephen is an avid folding bicycle rider, often taking his bike on overseas business trips, and is a proud dachshund owner.

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