What is Cycling Wind Tunnel testing?
A technology previously reserved for aerospace and Formula 1, a wind tunnel is an aerodynamic testing tool designed to measure the forces acting on an object moving through air. Built specifically as a sports research and development tool, Silverstone Sports Engineering Hub’s (SSEH) tunnel operates at speeds realistic to sports such as cycling.
Wind tunnel testing typically consists of an object, or in our case a rider or bike, being tested at various speeds and yaw angles (to simulate crosswinds) to assess the effectiveness of changes to equipment or position in terms of performance.
How does the SSEH wind tunnel work?
Simply put, air is sucked through the tunnel over the rider. Air is drawn through flow screens in order to smooth the flow and minimise turbulence. The airline area decreases, the air is squeezed and accelerates towards the test section where the desired airspeed is achieved. The forces acting on a cyclist are measured using a balance system located in the Ergo. To find out more about the features of a wind tunnel, check out our article here.
Importantly, aerodynamic drag (the largest force a rider will have to overcome on the flat) is measured. Reducing cycling drag is a key component in improving cycling performance.
Operating a wind tunnel
A tunnel technician operates the tunnel via a PC and is able to control the air speed and yaw angle, as well as communicate with the rider while they’re testing.
At SSEH, our bespoke software enables easy and efficient aero testing. The rotating turntable enables accurate and efficient crosswind simulation by yawing.
Simulating realistic conditions
Every athlete and event are different and therefore testing at the relevant yaw angles and speeds is important to make the most out of testing time. Yaw refers to rotating the turntable to simulate a crosswind that may be experienced during racing.
For example, the individual pursuit record yielded an average speed of approximately 37 mph where as the 180.25 km bike section record at the Ironman World Championships yielded an average speed of approximately 27 mph. The sterile environment in the velodrome has controlled ambient conditions. Whereas the Ironman World Championships hosted in Hawaii is renowned for being notoriously windy and subject to more varied environmental conditions.
Therefore designing a speed and yaw testing matrix that enables a full range of crosswind scenarios and realistic speeds to be tested is important to ensure that they are relevant to the athlete and event, allowing for the realistic simulation of competition conditions. It’s often the case that equipment or clothing that may work for one event may not be the most suitable choice for another.
The numbers game
Two key statistics the tunnel measures are drag force and CdA (aka drag coefficient multiplied by frontal area). The aim is to minimise these numbers as this means the power required to ride at a certain speed is less.
One method of lowering CdA is improving riding position. A more aerodynamic position, where the frontal area is less, saves watts that are normally required to overcome aerodynamic drag. The tunnel can detect smallest of drag savings.
A successful tunnel session
A wind tunnel is an advanced tool that enables sports scientists and engineers alike to attain an understanding of the importance of aerodynamics in sport. It can find medal winning equipment and position combinations. In fact, a successful wind tunnel session effectively and accurately assesses pre-determined variables of interest e.g. TT bar angle, overshoes or even position in comparison with a baseline to measure a change. A coach or athlete will use this to maximise performance.
Want to find out more about Cycling Wind Tunnel testing? If you’d like to arrange a meeting to discuss your requirements do not hesitate to contact us on 01327 222830. We’d be happy to answer your questions.