Effect of road friction and temperature on radial damping and stiffness of bicycle trailer tyres

This study investigates the dynamic radial stiffness and damping characteristics of bicycle trailer tyres under varying friction and temperature conditions. Using a cantilever test rig, we conducted free-fall impact experiments on two 20" tyres as used on bicycle trailers (Schwalbe Big Apple 50-406 and Schwalbe Kojak 35-406) across multiple inflation pressures (100–650 kPa), three surface friction conditions, and ambient temperatures ranging from −20∘C to 30∘C. Results demonstrate that both contact patch friction and temperature significantly influence tyre mechanical properties. The coefficient of restitution (COR) increased by up to 59% when the temperature rose from −20∘C to 0∘C for the Kojak tyre at low inflation pressure and the damping coefficient increased by 75% to 300% over the same temperature span, while variations remained within 5% for COR and within 30% for damping coefficient in the 10–30∘C range. Surface friction coefficient variations resulted in 2–3% differences in COR, with lower friction surfaces yielding higher energy return. Radial stiffness showed similar temperature sensitivity, with variations up to 33% at sub-zero temperatures but remaining relatively stable above 0∘C. This work provides the first quantitative relationship between carcass-related viscoelastic damping and tread-related frictional damping in bicycle trailer tyres. The findings enable more accurate vehicle dynamics simulations and improved suspension design for cargo bicycles and child trailers, contributing to enhanced comfort and safety while reducing road-induced vibrations experienced by young passengers.