The Test

Facebook like buttonTwitter like buttonEmail share button

All bicycle tires are tested on a rolling resistance test machine with a 77 cm drum and a DC electric motor. The drum is covered with diamond plate to simulate an average road surface.

rolling resistance test machine with a road bike tire mounted

Measurements are taken with an Arduino microcontroller equipped with custom software and hardware. Our setup calculates the average power required to keep the drum at a set speed for a period of 30 seconds. Using our custom setup to measure input power results in a very accurate rolling resistance measurement.

After a warm-up period of 30 minutes, three measurements per air pressure are taken. We then calculate the average of these three runs. After a correction for the electric motor efficiency and subtraction of the power required to spin the drum and wheel to the set speed, the result is the rolling resistance of the tire.

To guarantee our setup delivers consistent results over an infinite time period, we've built a calibration tool that's used to calibrate our machine to known values. We do not use control tires as we feel control tires do not provide a stable baseline over a longer period than 1 year.

The calibrations tool also provides a motor efficiency mapping that we use to calculate the rolling resistance of the tires to real watts.

Some facts about our "standard" rolling resistance test:

  • 77 cm drum diameter.
  • Standard test drum speed of 200 RPM which translates to a speed of 18 mph / 28.8 km/h.
  • Diamond plate drum surface.
  • 42.5 kg load.
  • Computerized measurements.
  • Controlled temperature between 21.5-22.5 °C / 70-73 °F.

For a detailed explanation of rolling resistance check Wikipedia.

Puncture Resistance

Steel needle puncturing road bike tire to test puncture resistance

Puncture Force Test

The puncture resistance test is performed with a 1 mm steel needle to which weight can be added.

The needle gets positioned at the center of the tread for the tread puncture test and on the sidewall for the sidewall puncture tests. More weight gets added until it punctures the tire.

The puncture test is performed 5 times for both the tread and sidewall. We then take the average of these 5 punctures and calculate this to a puncture force score in points. A score of 10 in the puncture force test means it takes twice as much force to puncture when compared to a score of 5.

Puncture Factor

Puncture Factor is calculated by multiplying the puncture force from the puncture test by the measured tire thickness. Just like the force required to puncture a tire, the thickness of the tread and sidewalls is also very important to prevent punctures in real-life.

What we've found is that casing material and anti-puncture strips take a lot of force to puncture. The rubber, on the other hand, doesn't take much force to puncture as it's a very soft material. We found that a tire without an anti-puncture strip but that does have a thick layer of rubber doesn't take a very large force to puncture. In reality, it does offer a lot of puncture protection because the thick layer of rubber simply doesn't allow the object to reach the inner tube.

Puncture Factor will give a better judgment of real-life puncture resistance than puncture force alone.