Tire Pressure CalculatorJan Heine
The new Rene Herse tire pressure calculator is based on hundreds of tests of tires from 20 to 55 mm wide. These tests have consistently shown that supple high-performance tires roll fastest at two distinct pressures: A relatively high pressure that provides a firm feel to the bike, and a low pressure that optimizes comfort.
Here’s why both pressures roll at the same speed on smooth pavement: Lower pressure means less vibration and less energy lost to suspension losses. That makes up for the higher hysteretic losses due to greater deformation of the tire. These two factors – suspension losses and hysteretic losses – are not linear. The result: Mid-range pressures actually roll a little slower than either high or low pressures.
The Rene Herse Tire Pressure Calculator takes this research and combines it with Frank Berto’s measurements of tire deformation under different loads for dozens of tires to create a calculator that provides consistent, reliable results for everybody regardless of their weight, not just for lightweight racers. This is also the first tire pressure calculator specifically for supple high-performance tires, where sidewall stiffness contributes relatively little to supporting the weight of bike and rider. (You can also use it for other tires, of course.)
Plug in tire width and rider/bike weight, and the calculator returns two values. Use the ‘Soft’ value for rides on rough roads or for a more comfortable ride. Use the ‘Firm’ value if you like your bike to have a firm feel. Either value will optimize your speed by reducing rolling resistance to a minimum.
In a future post, we’ll look at the science behind our tire pressure calculator.