A silk-reinforced bicycle tyre prototype aims to combine high-performance riding with a lower environmental footprint.
Prototype bicycle tyres reinforced with natural silk outperformed comparable nylon-reinforced tyres in durability, puncture resistance and cord strength.
Researchers in Thailand have developed a prototype high-performance bicycle tyre that replaces conventional nylon fabric reinforcement with natural silk.
The team combined laboratory-scale material testing with pilot-scale tyre manufacture. Natural rubber composites were produced by placing a layer of silk or nylon fabric between rubber sheets and bonding the layers using a resorcinol-formaldehyde-latex coating. The selected composite formulation was then used to manufacture full bicycle tyres.
Tests showed that the silk-reinforced rubber composite had higher tensile strength and better adhesion than the comparable nylon-reinforced material. Dynamic mechanical analysis also showed lower energy dissipation in the silk-reinforced composite, indicating reduced heat build-up under repeated deformation.
The prototype silk-reinforced tyre was compared with a nylon-reinforced control tyre made using the same basic structure and rubber formulation. It was about 10.5% lighter and achieved:
- 29% greater endurance;
- 57% greater puncture resistance; and
- 143% greater cord tensile strength.
The silk-reinforced tyre also showed substantially higher adhesion strength between the rubber tread and reinforcing cord.
The researchers linked this performance to the structure of silk fibres and their interaction with natural rubber. Silk contains protein-based molecular groups that can interact with components in natural rubber, while its fine fibrous structure can improve stress transfer across the composite interface.
Scanning electron microscopy showed good contact between the coated silk fabric and the rubber matrix, with few visible interfacial voids. The silk fibres also had a finer structure than the nylon fibres, which may have contributed to more effective reinforcement.
The team also conducted a gate-to-gate life cycle assessment comparing the material inputs used to produce one kilogram of silk- and nylon-reinforced tyre material.
Within the limits of the assessment, the silk-reinforced tyre showed lower impacts across the four categories examined. Its estimated global warming potential was 0.79 kg carbon dioxide equivalent, compared with 5.06 kg for the nylon-reinforced tyre. It also showed lower fossil-resource depletion, ozone-depletion potential and photochemical oxidation potential.
The assessment covered material inputs within the tyre-production facility. It did not include upstream raw-material extraction, factory energy consumption, tyre use or end-of-life treatment. The environmental results should therefore be interpreted as a comparison within this defined gate-to-gate boundary rather than as a full life-cycle comparison.
The study demonstrates that natural silk can function as more than a renewable substitute for synthetic reinforcement. In this prototype, it improved several mechanical and tyre-performance measures while also reducing the environmental impacts captured by the study.
The researchers note that longer outdoor trials are still required. Future work will need to examine performance under real cycling conditions, production at larger scale and further optimisation of the bond between silk and rubber.
Paper details
The paper, “Development of Sustainable Rubber Composites Reinforced with Silk Fabric for High-Performance Bicycle Tires: Material Characterization and Prototype Testing”, was published in ACS Omega in 2025. DOI: 10.1021/acsomega.5c05422.
The research was led by Dr Wirasak Smitthipong at Kasetsart University, Thailand, in collaboration with researchers from Bangkok Metropolis Motor Co., the University of Haute-Alsace, the University of South Brittany and the University of Cambridge.
Dr Kheng-Lim Goh of Newcastle University advised the team on the design, execution, validation and interpretation of the gate-to-gate life cycle assessment, and on the mechanics of fabric reinforcement in rubber composites.
For further details, contact Dr Wirasak Smitthipong, Kasetsart University, at [email protected], or Dr Kheng-Lim Goh, Newcastle University, at [email protected].
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