Tire dependence for the aerodynamics of yawed bicycle wheels

The aerodynamic characteristics of a modern road cycling wheel in cross wind are studied through force- and planar PIV measurements in the TU Delft Open Jet Facility. The performance of the 62 mm deep rim is evaluated for three tire profiles, and yaw angles up to 24°. All measurements are executed at 12.5 m/s (45 km/h) freestream- and wheel...

Aerodynamics of a cycling wheel in crosswind by coaxial volumetric velocimetry

The aerodynamic characteristics of a modern road cycling wheel in crosswind are studied through force measurements and 3D velocimetry in TU Delft’s Open Jet Facility. The performance of the 62 mm deep rim is evaluated for two tire profiles, and yaw angles up to 20◦ . All measurements are executed at 12.5 m/s (45 km/h) freestream- and wheel...

Cyclist Reynolds number effects and drag crisis distribution

The Reynolds number effects on body limbs of a cyclist model, namely leg and arm, are investigated via robotic volumetric Particle Image Velocimetry measurements in the velocity range from 5 ​m/s to 25 ​m/s. The near wakes of such body limbs feature recirculation regions whose width and length are governed not only by the taper of the body...

Uncertainty assessment of the Ring of Fire concept for on-site aerodynamic drag evaluation

The Ring of Fire (RoF) measurement concept to perform on-site experiments of aerodynamic drag for transiting objects is investigated with a study that identifies the main sources of uncertainty. The main contributors to the uncertainty of the drag measurement are examined for the case of a cyclist riding through the measurement domain. A...

Drafting Effect in Cycling: On-Site Aerodynamic Investigation by the ‘Ring of Fire'

An on-site Ring of Fire (RoF) experiment is performed at the Tom Dumoulin bike park in Sittard-Geleen, the Netherlands. The current work investigates the aerodynamic drag of a cyclist following a lead cyclist at different lateral and longitudinal separations; additionally, the athletes’ skills to maintain their position and distance with respect...

A Novel Approach for Skin Suit Aerodynamic Optimization Using Local Momentum Deficit

A new approach is introduced to evaluate the potential drag reduction by skin suit design in speed sport. The approach relies upon local flow information measured in the wake of a cyclist mannequin. Lagrangian Particle Tracking is employed to measure the distribution of time-average streamwise velocity in a cross-plane of 30 × 100 cm2 behind the...

The Ring of Fire for in-Field Sport Aerodynamic Investigation

A novel measurement system, the Ring of Fire, is deployed which enables the aerodynamic drag estimation of transiting cyclists. The system relies upon the use of large-scale stereoscopic PIV and the conservation of momentum within a control volume in a frame of reference moving with the athlete. The rider cycles at a velocity of approximately 8...

Aerodynamic drag determination of a full-scale cyclist mannequin from largescale PTV measurements

Large-scale Particle Tracking Velocimetry (PTV) measurements are cond ucted in the wake of a fu ll-scale cyclist model in time-trial position at freestream velocities between 12.5 and 15 m/ s, corresponding to Reynolds numbers of the order of 5×105. Lagrangian particle tracking is employed to determine the velocity and static pressure statistics...