Creating new cycle helmets
Cycling equipment has evolved over the years from research in a variety of fields, including engineering science.
Cycling helmet wind tunnel test
A prototype cycling helmet from a 3D printer being tested at Canterbury University’s wind tunnel. Different hole configurations are used to determine how the number and location of holes affect aerodynamic drag and heat loss.
Dr Lindsey Alton, Guilhem Cornillon and Pierre Eloi (CPIT) and Dr Mark Jermy (University of Canterbury) are using 3D printers to test new helmet designs aimed at reducing aerodynamic drag.
3D printing builds 3D models by adding successive layers of material using a computer programme. It enables slight tweaks to be made in designs, in this case, of the cycling helmets.
How to improve performance
During a race, cyclists need to gain speed to improve their performance. A cyclist transmits power to the bike, which in turn transforms it into speed. There are two ways to improve this performance: either increase the power transmitted or reduce the power needed.
Reducing aerodynamic drag
One solution to reduce the power that is needed is to minimise the loss of power caused by the headwind, called aerodynamic drag. Aerodynamically efficient equipment helps reduce the forces slowing a cyclist down. This makes it easier for them to maintain a higher speed. At the same time, it saves their energy and so improves their endurance, leading to an improved overall performance.
The cyclist’s helmet
An important piece of a cyclist’s equipment is the helmet, which provides essential head protection.
This project aims to look at the aerodynamics of helmets used in competitive track cycling, studying both the positioning on the head and shape, size, number and placement of aeration holes. At the same time, the temperature of the head is measured to understand how the aeration influences heat concentrations around the head.
3D printing
A complete helmet shell was designed and manufactured using 3D design software and a 3D printer. A flexible heating resistance was then added inside the head to allow measurement of the temperature variations under the helmet.
Wind tunnel testing
The wind tunnel
Dr Mark Jermy describes how the wind tunnel at the University of Canterbury works and how it can be used to measure forces on cyclists. He describes how the drag force is measured using strain gauges and how voltages produced by the strain gauges are calibrated to give an accurate result for the aerodynamic drag on a cyclist.
The research team are using Canterbury University’s wind tunnel to analyse airflow and drag as high-speed wind moves over the various helmet prototypes. The results will help determine how the number and location of holes affect aerodynamic drag and heat loss.
Each helmet will be evaluated in term of aerodynamic and thermic performances in order to define the best helmet design. This research could be used to assist the New Zealand cycling team to improve their race speeds.
Activity idea
In the activity, Investigating airflow over shapes students investigate the aerodynamics of various shapes. They observe airflow over the shapes to find out which shape is likely to produce the least aerodynamic drag.
Related content
In this issue of Connected, Beating the wind is about cycling aerodynamics and features both Lindsey Underwood and Science Learning Hub resources.
