Rolling Resistance Testing

Have you ever wondered what the fastest tyre choice is for a road ride? With tyre manufacturers often claiming to have the fastest tyre on the market, it’s easy to become confused by all of the available offerings. Recently at Silverstone Sports Engineering Hub, we tested a range of tyres on our Rolling Resistance Rig, in order to show the typical differences to be expected between tyres.

Method

8 different tyres were tested using our Rolling Resistance Rig here at SSEH. The rolling resistance rig has been designed to test and quantify the rolling resistance of a bicycle wheel and tyre. It does this by measuring the difference between the power required to spin up a roller with and without a wheel running on it. The wheel is loaded with a specific mass in order to simulate a rider’s weight. The roller is connected to a torque meter, which enables the rolling resistance to be quantified by comparing the power required to drive the roller at a constant rotational speed, with and without a tyre in contact and thus the power required to rotate the wheel. The rig is capable of measuring marginal differences, such as tyre pressure, or change in the contact patch load (equivalent to changing the rider mass).

Testing protocol

To enable investigation of the tyre’s rolling resistance, the testing protocol used a single speed of 40kph. A 30 second record of each test speed was used, and the rolling resistance was averaged over this time. The tyre was also warmed up on the rig for 10 minutes at 50kph. A contact patch load of 40kg was applied to the tyre during the testing. All of the tyres tested were labelled as 25mm.

Results

A large spread of rolling resistances can be seen in the data, ranging from extremely low values of 8.9W, all the way up to larger values of 18.6W. Despite the tyres all being labelled as 25mm by the manufacturers, their widths also varied between 24.1mm and 27.4mm. Throughout the testing, the temperature of the tyres increased from 22°C for Tyre 1, then remaining constant at 25°C from Tyre 5 onwards. Interestingly, the rolling resistance and width seem to be independent, with the faster tyres being both extremes of width.

Conclusion

At 40kph, the tyre with lowest rolling resistance was tyre 8, with an impressively low value of 8.9W. The tyre with the highest rolling resistance was tyre 5, with a value of 18.6W. Amongst this selection of tyres, the correct tyre choice can therefore save a rider up to 9.7W.

If you would be interested in arranging a session on our Rolling Resistance Rig to optimise your own tyre choices choices, please refer to the Cycling Test Lab section of our website for further information – https://silverstonesportshub.co.uk/cyclingtestlab/