Kirsten Dijkman successfully defended "Impact of bicycle tire parameters on the total rolling losses" on January 11, 2024. Kirsten executed three experiments to investigate all aspects of forward motion energy losses due to the bicycle-rider system rolling on different road surfaces. She first characterized the tire contact patch for a set of modern tubular and tubeless racing tires, finding that tire carcass diameter had no effect on contact patch length and that inflation pressure (in the range tested) had no effect on contact patch width, but tire type and vertical load all correlate to contact patch dimensions. She then tested these tires for rolling resistance on a traditional drum testing machine and found that all testing variables (tire dimensions, pressure, load, and rolling speed) predict rolling resistance. Tubeless tires have more rolling resistance than tubular and rolling resistance decreases with increasing inflation pressure and decreasing speed. In the third experiment, Kirsten developed a first-of-its-kind trailer to create a windless environment for a cyclist to travel over any road surface which we named "De Veeger". She then measured rider input power over smooth asphalt and bumpier bricks to characterize the total rolling losses due to both the tire properties and the vibrational damping losses in the bicycle, suspension, and rider. This revealed a clear dependence on road surface type and travel speed: bricks and higher speeds causing more rolling energy loss. However, the input power estimates were not precise enough to show any effect of tire properties on the total rolling losses, which leaves room for future improvements to the measurement system.

Kirsten was co-supervised by Andrew Dressel (TU Delft & University of Wisconsin, Milwaukee), Harm Ubbens (Team DSM), Piet Rooijakkers (Team DSM), and Jason K. Moore (TU Delft). Thanks to Jan van Frankenhuyzen, the ME workshop, and Dijkman Carbaat Bouw for all the help. Everyone at the bicycle lab is very proud of Kirsten and wishes her the best in her next adventures.