The number of wheel-only tests that can be completed per hour depends on the specific test protocol, including the number of wind speeds and yaw angles being evaluated.

As a general estimate, wheel-only testing typically takes 15–20 minutes per wheel, allowing for approximately 3–4 tests per hour.

The SPWT is capable of testing at speeds of up to 28m/s (approx. 100kph or 60mph), but limited to 22m/s for cycling, with a yaw range of 0 to +/- 30 degrees (representative of real world conditions).

The SPWT is able to accommodate all road, track, and time trial/ triathlon bike axle standards. We also have fixtures to be able to accommodate some mountain bike standards, however would require confirmation of the bikes specification prior to testing.

Prior to testing, all customers will be provided with a safety briefing by the tunnel operator which includes the location of the fire exits, PPE required, safely moving equipment in and out of the wind tunnel and what to do during testing. You will also be shown the location of the changing facilities and social area for making drinks etc.

During the session, the wind tunnel will be operated by an SSEH Technician or a trained tunnel user. The Technician will carry out the safety briefing outlined in section 2.1 and also be responsible for operating the tunnel in accordance with a pre-agreed testing protocol.

Please note; in order to uphold our impartiality, the Technician will not be able to offer aerodynamic advice during the session. If this service is required, please refer to 'Aerodynamic advice/consultancy services' for further guidance.

In order to achieve our goal of providing industry leading R&D facilities for the advancement of sports engineering and athlete development to both manufacturers and teams, we feel it is important for us to provide an impartial and fully confidential service. As such, we choose not to provide aerodynamic advice
ourselves, however, if this is required, we have many of the industry leading performance consultants making regular use of our facilities who would be able to accommodate your requirements.

If you would be interested in receiving further guidance during your session, we have created a section on our website with a list of current consultants.

The equipment you should bring with you on the day will vary dependant on your testing protocol and what you are looking to focus on during the session. As a guideline, we would suggest ensuring you bring the following items:

• Bike
• Wheels/ additional wheel configurations if required
• Helmet
• Glasses (if usually worn when riding)
• Pedals
• Cycling shoes
• Cycling clothing

Yes, if required, SSEH can provide a bike and/ or a rider on request. This can often be helpful for companies based overseas looking to keep travelling time and expenses to a minimum. Please be advised that this service would be chargeable at the standard hourly Technician rate.

More information on our remote testing service

The SSEH Equipment Room was designed to enhance the customer's experience of the Sports Performance Wind Tunnel by providing the resources required to carry out thorough and precise aerodynamic testing of products from the cycling performance market.

We have created, with the support of many of the leading cycling and apparel brands, a variety of options which can be included in a customer’s test programme at no cost. This provides the rider with the opportunity to test products in the market, to ensure they are maximising their aerodynamic potential.

In order to enhance accuracy of testing it is important to take a tare of the rider/ equipment prior to starting the test. This is performed without the wind on and used to isolate and subtract the load of the rider/ equipment and any static offsets from the drag data.

When choosing the sample time of each test, it is important to factor in the variation of drag measured by the rider/ equipment throughout the test. For all testing, whether rider, or just equipment, we would recommend a minimum of 30 seconds per record, in order to obtain an accurate average.

Depending on the time available, it can be useful to conduct tests at two or more wind speeds to create a clearer picture of drag at the speeds you may encounter in real-world riding. As a starting point, it is advisable to pick a baseline speed based on the riders typical average speed for the event. Depending on the number of runs you wish to complete and the time available, you may then choose to repeat the test at a different speed.

In the wind tunnel, we are able to rotate the ergo platform to change the effective orientation of the rider to the wind, simulating a crosswind. This is referred to as yaw. Yaw angle is the resultant
vector generated by the magnitude and direction of travel and a cross wind.

During your test, riders have the option to include one, or more yaw angles to build a clearer picture of how a change in position, or equipment may perform under different conditions.

The ergo is capable of reaching yaw angles of up to +/- 30 degrees, which is representative of conditions a rider may face in real-world riding.

In order to better understand the time taken to perform one run during testing, please find the example protocol below based on 3x yaw angles and 2x test speeds:

30 second samples at 2x speeds and 3x yaw angles (6x events for each run), would equate to 180 seconds of data recording. We would expect this run to take approx. 5 minutes (300 seconds) accounting for the rider settling into position, taking a zero-wind tare at the 3x yaw angles, turning the fan on/off, and changing wind speed/yaw angle.

To provide a more realistic body position on the bike, we are able to provide resistance for the rider to push against whilst pedalling. To ensure repeatability, it is advised to select an intensity that can be easily sustained throughout the duration of testing, whilst providing enough resistance to hold a position representative of what the rider would adopt on the road/ track. A good starting point would be approximately 50% of the riders functional threshold power.

To achieve accurate and repeatable results during testing it is imperative for the rider to maintain their position on the bike throughout each test run. This can be achieved via the use of our live rider edge outlines. When taking a tare, the tunnel operator has the option to capture an edge outline of the rider that can then be seen both on the tunnel control room computer and projected on the display in front of the rider. This visual aid acts as a cue for both the rider and tunnel operator to ensure they maintain position throughout the test.

In addition to the rider edge overlays, wind tunnel customers also have access to Aerobody, an optical sensor which measures the position of a riders head and chest in relation to the stem or top tube of the bike.

The device has been integrated into the wind tunnel software, with an initial measurement taken during the tare. The position of the riders head and chest can then be monitored in real time by both the athlete and wind tunnel operator in order to ensure position is maintained.

Taking the information in this section into account, we would advise you to include the following best practice measures into your testing protocol:

• Taking a tare prior to each test run.
• Selecting a power and cadence that will be sustainable and repeatable for the duration of the test programme.
• Utilising the rider edges function to maximise repeatability.
• Selecting a suitable range of test speeds and yaw angles dependant on the athletes event history, or target event.
• Checking the baseline results repeat.

The wind tunnel instrumentation records data for a larger number of metrics such as ambient air and wind conditions, yaw angle and drag force measurements. Raw data is recorded at a sample rate of
100Hz.

Using an extremely sensitive six-loadcell force balance combined with an extensive force calibration process, aerodynamic drag is measured in the axis of the bike, the direction of travel.

Cycling metrics such as rider cadence, wheel power and wheel speed are also measured for reference information.

There are a large number of complex factors which affect drag including the ambient air conditions and velocity as well as the size, shape and surface texture of a body.

Analysing drag alone does not provide a clear picture of aerodynamic performance. CdA (Coefficient of Drag x Frontal Area) is a metric calculated and used to evaluate aerodynamic performance, considering the drag, air density and wind speed. The lower the CdA, the more ‘slippery’ an object is and will therefore experience less air resistance. CdA for cyclists typically range from ~0.15 to 0.4.

Using the drag force measurements, the ‘aero’ power required to overcome aerodynamic drag and move a body through the air at a specified speed is also calculated. Results are provided in the form of ‘watts’, in which athletes can easily relate to when understanding performance gains and reduction in power.

In reality, reducing drag and lowering your CdA allows you to ride faster for the same power output. Speed increases and time savings can then be calculated.

Repeatability is key to understanding and validating wind tunnel test data. Unless variables are meticulously monitored and controlled, the variability of results could be greater than the marginal differences attempting to be measured. How a wind tunnel session is managed can often influence the quality of results obtained.

The wind tunnel hall is temperature controlled and the wind tunnel control software compensates for changes in ambient conditions to prevent drift in results through maintaining either a constant Dynamic Pressure or constant Reynolds Number, normalising drag for STP (Standard Temperature and Pressure) conditions. This also helps to achieve comparable results if comparing data to that recorded on another day, where the ambient conditions may differ. What the wind tunnel cannot account for is how a human body reacts to ambient conditions and physical exertion. A change in body temperature or perspiration could well affect air flow
characteristics and therefore drag.

The test variable is the thing that is to be changed in order to measure aerodynamic differences (whether a different component, equipment or change in rider position). To accurately measure and quantify the differences that a change has produced, all other variables must remain constant. Examples of variables that could influence results and therefore should be considered are:

• Bike installation, vertical alignment.
• Bike accessories: computer head unit, drinks bottle, bottle cages etc.
• Rider or mannequin position: hands, arms, head, shoulders, back, position on saddle.
• Helmet fitment and orientation.
• Clothing fitment: zip position, pocket positions, sleeve lengths, short lengths, sock heights, position and orientation of seams and fabric detail.
• Rider effort, power, cadence.
• Gear selection, wheel speed.
• Ability of rider to maintain a position.
• Rider fatigue, temperature, perspiration.
• Crank position (if bike only testing).
• Wheel orientation and tyre valve position (if wheels are static).
• Wheel fixture position (if testing a wheel in isolation).
• Tyre pressure.
• Yaw sweep direction.
• Possible aerodynamic instabilities of static objects (such as a mannequin).

A rider simply getting off the bike and straight back on again can induce positional, helmet and clothing differences as well as a change in weight distribution on the force balance, all of which could have an effect on the drag measurements. Utilising software tools such as the photos, live athlete edges and taking a tare before a run will help to minimise unwanted variables. It is important to conduct baseline repeats to understand the variability of a test specimen to validate changes and results.

No two wind tunnels are the same. The design and architecture of the airline and test section, air flow characteristics, fan size and configuration, test specimen restraints, force balance design, calibration methods, compensation methods, and output calculations used will all affect the characteristics and outputs of a wind tunnel.

In reality, a bike is not constrained by stanchions and moves over a surface whilst passing through the air (rather than held on a static surface with moving air). Using constant Dynamic Pressure or Reynolds Number compensations has significant benefits for repeatability, but normalising drag for standardised conditions may contribute to over or under estimations. Aerodynamic blockage is always a factor within wind tunnels when comparing with real world conditions, the open jet configuration of the SSEH SPWT minimises the effect of blockage whilst allowing for testing at yaw angles. All of these factors could contribute to CdA being slightly higher in the wind tunnel than in real life. But one of the major benefits of a wind tunnel is controlled conditions, therefore making it easier to measure marginal differences.

It is important to remember that the wind tunnel is not the same as the real world, but can be used as a comparative tool, ultimately comparing relative differences of A vs B rather than establishing absolute values.

Tools such as Computational Fluid Dynamics (CFD) or controlled real-world testing also have different pros and cons, but can be used to compliment wind tunnel testing and help further validate and understand wind tunnel results.

No. Air flow characteristics, drag and CdA will change with wind speed and yaw angle. Something which works well at one speed or yaw may not work as well at another. It is therefore important to test over a range of relevant conditions.

No two riders are the same, again something which works well for one person may not necessarily work well for another. The performance of a standalone item or change often depends on the interaction with the other bodies around it and how it works as a full package or system.

During testing we have two forms of data collection available. The first is in a raw spreadsheet format, with all data points recorded line by line. The second is Aero Data Centre (ADC), a cloud based analysis software. The raw data files are presented in a CSV format and can be analysed in a tabular format using Excel. Postprocessing
of the raw data may be required as per the clients requirements typically using their own pre-determined results
template.

ADC has been developed for SSEH by Bramble to present the data in a user friendly format, allowing for quick comparison of each test run. The software provides the following features:

• Intuitive platform with data presented in a professional looking format which is easy to interpret and understand.
• Reduces the requirement to manually process raw data files in order to efficiently evaluate and compare results.
• Results instantly processed and reported immediately after each run.
• Easily accessible on multiple devices or viewed remotely away from the wind tunnel.
• All data stored and managed in one secure location.
• Historical data can be easily reviewed.
• Ability to run ‘aero maps’ to automate the wind tunnel control:
  • Pre-defined test conditions such as wind speed, yaw angle and sample time.
  • Reduces manual inputs and therefore the 2. time to run a test.
  • Gives the operator time to analyse the data, prepare test samples and attend to clients whilst the wind tunnel is in operation.
• Simple evaluation and comparison of results providing percentage and absolute differences to a selected baseline.
• Ability to convert CdA and Drag differences to performance metrics such as power saved, speed increase or distance gained.
• Averaging of repeats to provide more accurate results.
• Ability to take tabulated data and plot in graphs for a range of variables and comparison of different runs.
• Apply notes and descriptions to each run, which can be reviewed after the session for further clarity of the configuration.
• View and compare footage of each data record and overlay athlete edges.

Once you have completed your session, it is suggested that you take the raw data away with you, so it can be removed from the tunnel computer. In order to do so, please bring a storage device with a minimum capacity of 128gb.

If for any reason you are unable to bring a storage device with you, we will save the data to our own device and send a secure link to download the data remotely. Once this has been completed, we will then delete the data from our system.

If using ADC, data will be uploaded immediately after recording. The raw data files will still be available to download from the tunnel computer at the end of the session.

Once you have completed your session and downloaded the data to your storage device, we will ensure your data is removed from our system.

If using ADC, data is stored on your own secure account hosted by Bramble, in which SSEH will not have access to once the session is complete. All data saved to your account will remain accessible for a period of 12 months from your last session. If the account is reactivated for a session after this period, all historical data will become accessible again.

As well as remaining impartial, we also treat each session with full confidentiality, ensuring our clients remain anonymous and their data is not shared or accessible to other tunnel users.

When developing clothing or equipment, customers have the option of hiring a mannequin for testing. The mannequin ensures a constant position is achieved throughout testing, maximising repeatability, which is essential when aiming to identify marginal differences between test runs.

If you would be interested in testing the aerodynamics of wheel and tyres in isolation or on a bike (without a rider), we are able to support this in the Sports Performance Wind Tunnel with the option of testing either a static or spinning wheel.

Spinning wheel tests are performed via the use of a powered roller, capable of spinning a wheel to a maximum of 55kph. The benefit to testing a spinning wheel is that it provides data that is more representative of real-world riding.