How to Perform Aero Testing at Home: A Step-by-Step Guide for Cyclists

Besides your power output, how aerodynamic you can make yourself the greatest factor in how fast you can become in cycling.

Getting your CdA (Coefficient of Drag x Frontal Area) as small as possible will allow you to ride faster for less effort. Wind tunnel testing is the gold standard for optimising aerodynamics, it’s highly accurate and allows minute changes to be studied, however it’s often inaccessible due to cost and location.

Thankfully, with modern tools and the innovative Chung Method, you can perform aero testing at home. By combining equipment most serious riders now own like power meters and speed sensors with free software such as Golden Cheetah, you can fine-tune your position and gear to ride faster and more efficiently.

This guide explains everything you need to know about at-home aero testing, from understanding the methods to setting up your tests and analysing the results.

Why Is Aero Testing Important?

• At higher speeds, aerodynamic drag accounts for 80+% of the resistance you face. Reducing your drag coefficient (CdA) allows you to optimise your position and equipment like helmets, clothing and bike setups to find the most aerodynamic options. The result being that you can:

• Ride faster: Achieve higher speeds with the same effort.

• Save energy: Conserve energy for critical moments, such as sprints or climbs.

Rolling resistance, though smaller in effect, also matters—especially on rough surfaces. By understanding both aerodynamics and rolling resistance, you can make informed decisions to maximise your performance.

Getting Started with Aero Testing

Before diving into specific methods, follow these essential tips for accurate and reliable results:

1. Choose the Right Route: Find a quiet, safe course with minimal traffic, smooth surfaces, and no unexpected obstacles.
2. Start and Finish at the Same Point: This ensures the net elevation change is zero, making data analysis simpler.
3. Pick Calm Conditions: Avoid windy days, as gusts can distort your results.
4. Maintain a Steady Position: Hold the same posture throughout each test run.
5. Maintain a steady speed: Braking and accelerating mid-run can interfere with your data, so aim to complete runs smoothly.

Virtual Elevation

The virtual elevation method, developed by Robert Chung, is the foundation of at-home aero testing. Here’s how it works:

• Aerodynamic Drag: Power required to overcome drag increases as a cube function with speed. Doubling your speed creates four times the drag and requires eight times the power to overcome.
• Rolling Resistance: This increases linearly with speed. Doubling your speed doubles the power needed to overcome rolling resistance.

By analysing power, speed, and elevation data, you can estimate your drag coefficient (CdA) and rolling resistance coefficient (Crr) in Golden Cheetah (GC). To get your true value for these, shift your estimated numbers in GC up or down until the virtual elevation metric matches the actual elevation recorded during your ride.

Step-by-Step Testing Protocols

The Chung Method

The Chung Method is ideal for closed loops and is considered the most accurate for aero testing.

What You’ll Need:

• A power meter.
• A dedicated speed sensor for precise measurements.
• A bike computer that can provide altitude data.

How to Perform the Test:

2. Find a Loop: Choose a closed circuit with smooth turns and a slight incline, lasting 30 seconds to 5 minutes per lap.
3. Do Multiple Laps: Perform at least three laps (five or six are better) without braking.
4. Vary Your Power: Do three separate runs for more data. Conducting these runs as low, medium, and high efforts will help collect diverse data.
5. Hold Your Position: Stay consistent in your riding posture to avoid skewing the results.

The Shen Method

If you don’t have access to a loop, the Shen Method is a great alternative using an out-and-back course.

What You’ll Need:
Same as the Chung Method: power meter, speed sensor, bike computer that records altitude data altitude data.

How to Perform the Test:

1. Set Up an Out-and-Back Route: Place a marker at the turnaround point for consistency.
2. Turn Smoothly: Avoid braking at the turn, or brake hard at a fixed point to make this point easily visible in your data file so it’s easier to edit.
3. Do three separate runs for more data. Conducting these runs as low, medium, and high efforts will help collect diverse data.
4. Hold Position: Stay steady in your posture, as consistency is key.

Coast-Down Testing

This is the easiest method if you don’t have a power meter.

What You’ll Need:

• A dedicated speed sensor (critical for accuracy).
• A cycling computer with an altimeter.

How to Perform the Test:

1. Choose a Gentle Descent: Find a consistent downhill segment.
2. Coast at Different Speeds: Perform three runs at slow, medium, and fast speeds.
3. Edit Your Data: Ensure start and end points are consistent before analysing results.

Single Climb Test

This protocol is perfect for gravel surfaces or when loops aren’t practical.

Same as the Chung Method: power meter, speed sensor, bike computer that records altitude data altitude data.

How to Perform the Test:

1. Find a Steady Climb: Choose a hill lasting 1.5 to 5 minutes.
2. Perform runs at low, medium and high power to collect diverse data.
3. Analyse in Software: Import your data into Golden Cheetah and adjust CdA and Crr until the virtual elevation profiles align.

Analysing Your Results

To analyse your data:

1. Upload to Software: Use a free tool like Golden Cheetah.
2. Adjust CdA and Crr: Tweak these values until your virtual elevation matches your actual elevation.
3. Compare Setups: Test different equipment or positions and note how changes affect your drag and rolling resistance.

If you want to be quick and dirty about it, A/B testing can be done even without golden Cheetah.

Edit your data so that the start and end points are consistent. Making or using a segment on Strava can be done for this if the route is long enough for where small changes can result in differences of over a second in finish time. Simply look a how fast one run was in comparison to another after making one change. Complete the segment faster across multiple runs? Congratulations you found some gains!

Conclusion

Aero testing doesn’t have to cost a fortune. By using the Chung Method or alternative protocols, you can gather precise data to optimise your performance.

Whether you’re refining your position, testing gear, or experimenting with tyre pressures, these methods give you actionable insights to ride faster and smarter.

For even greater gains, pair your optimised setup with our aero kit, designed to reduce drag and give you a competitive edge.