Your Tires Could Be Costing You Minutes. Tire Rolling Resistance with Josh Poertner

Summary

In this video, Josh Portner, a pioneering expert in marginal gains, discusses the crucial factors influencing tire rolling resistance and how optimizing tire pressure can significantly improve cycling performance. He explains the science behind tire pressure, the role of hysteresis in tire design, and debunks common misconceptions about tire choice. Josh emphasizes that lower tire pressures often result in lower rolling resistance and greater comfort, challenging traditional road cycling beliefs. The conversation also touches on innovations like tubeless sealants and tire inserts, providing insights on how they contribute to speed and efficiency. This discussion is packed with actionable advice for cyclists aiming to go faster.

Takeaways

• 😀 Lower tire pressure can reduce rolling resistance, improving speed by reducing energy loss from tire deformation.
• 😀 Many cyclists overinflate their tires, resulting in increased rolling resistance and slower speeds. Most cyclists run pressures that are too high for optimal performance.
• 😀 Tire pressure calculators are useful tools for optimizing tire pressure based on factors like tire width, weight, and course conditions.
• 😀 A lower pressure tire is not just more comfortable but can also help you produce fewer watts at a given speed, improving efficiency.
• 😀 Tire inserts can help prevent flats, but depending on their design, they can add rolling resistance if they touch the tire sidewalls.
• 😀 The rubber compound of the tire plays a significant role in its performance; tires with lower hysteresis (energy lost due to deformation) are generally faster.
• 😀 Lighter tires tend to have lower rolling resistance, but the relationship between tire weight and rolling resistance is complex and not always linear.
• 😀 Tubeless tires allow for thinner tires with fewer layers, reducing hysteretic losses and improving speed and comfort.
• 😀 Some tire technologies, like those using latex or advanced rubber compounds, are more efficient due to their lower hysteresis, providing better performance.
• 😀 Testing in real-world conditions is essential to determine which tire and pressure combinations perform best for different surfaces and conditions.
• 😀 Tire pressure should be adjusted based on surface conditions and course type; too low a pressure can be inefficient, but too high a pressure is typically worse for performance.

Q & A

Why does selecting the right tire and tire pressure matter for cycling performance?

The right tire and tire pressure can significantly impact your speed, potentially saving you 10 to 20 watts or more. Small adjustments in tire selection and pressure can make a noticeable difference in cycling efficiency and overall performance.

What role does tire pressure play in reducing rolling resistance?

Lower tire pressure reduces rolling resistance by improving contact with the surface, making the tire more compliant and less energy-consuming. However, there is an optimal pressure range, as too low or too high pressure can increase rolling resistance.

What is the misconception about tire pressure in cycling?

Many cyclists believe that higher tire pressure is always faster, but the truth is that lower pressure is often more efficient. While higher pressure reduces casing losses, it increases impedance losses, making the tire less efficient overall.

What did Josh Portner and his team discover about tire pressure and rolling resistance?

Josh Portner and his team found that the rolling resistance decreases slightly with increasing pressure, but after a certain point, the impedance (vibration losses) increases significantly. This makes lower pressures more efficient for most cyclists.

How do tire width and rider weight affect optimal tire pressure?

Tire width and rider weight are crucial factors in determining the optimal tire pressure. Wider tires and heavier riders typically require slightly different pressures for optimal performance. A tire pressure calculator can help determine the best pressure based on these variables.

Why is tire compound and construction important in determining rolling resistance?

The rubber compound and tire construction, including the number of threads per inch (TPI) and the casing material, affect rolling resistance. Tires made with low hysteresis rubber compounds or thinner casings tend to have lower rolling resistance.

How does a tire's tread pattern affect its speed and rolling resistance?

While the tread pattern can influence rolling resistance, especially for off-road cycling, smoother tires generally have lower rolling resistance compared to knobby ones. For road cycling, the tread pattern is less of a factor compared to tire material and pressure.

What role does sealant play in improving tire performance?

Tubeless sealants allow for thinner tires with fewer layers, which reduces hysteretic losses. This leads to faster and more efficient tires, as sealants help prevent punctures while maintaining low rolling resistance.

How does tire insertion technology impact rolling resistance?

Tire inserts can add some rolling resistance due to the foam material, but their effect depends on the type and size. Inserts designed to protect the tire without affecting the sidewall too much have a minimal impact on rolling resistance while providing safety benefits.

What is the difference between high and low hysteresis materials in tire construction?

High hysteresis materials, like memory foam, convert more energy into heat, increasing rolling resistance and reducing efficiency. Low hysteresis materials, such as high-quality rubber compounds or foams, minimize energy loss, making the tire faster and more efficient.