Rolling Resistance in Cycling
Optimising Tyre Choice for Maximum Efficiency
In cycling, aerodynamic drag is widely recognised as one of the primary resistive forces acting on the rider. However, when pursuing marginal gains, focusing solely on aerodynamics overlooks a critical factor: rolling resistance and total system efficiency.
Beyond aerodynamic drag, performance losses occur through drivetrain inefficiencies, mechanical properties of the frame, and, critically, tyre rolling resistance. These combined losses contribute to overall cycling power loss, directly impacting race-day performance.
Why Rolling Resistance Matters in Cycling Performance
Rolling resistance is the energy lost as a tyre deforms while in contact with the road surface. While often underestimated, it plays a significant role in cycling efficiency, particularly over long distances and at high speeds.
Even small reductions in rolling resistance can translate into measurable gains, making tyre selection a key factor in marginal gains cycling strategies
Pedalling Efficiency Rig (PER): Measuring True System Loss
The Pedalling Efficiency Rig (PER) at Silverstone Sports Engineering Hub was used to carry out this investigation.
The PER measures:
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Power input from the athlete
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Power output at the roller (useful power, propelling the rider forward at the road surface
From these values, the PER can quantify the losses and state it in terms of efficiency or absolute power loss. A change in the system setup will be noted as a change in efficiency, allowing for the optimisation of equipment choices.
By isolating variables, the PER enables accurate cycling performance optimisation, helping teams identify the most efficient equipment setup.
Test Method: Controlled Rolling Resistance Analysis
A speed sweep was carried out between 8m/s and 12m/s, at 1m/s increments, with a sample time of 30 seconds. The tyre pressure was kept at 110psi. The chain tension was kept the same and a fixed gear bike was used to ensure no change in chain alignment.
The participant ramped up to 8m/s and when at a constant velocity, the first sample was run. Once the sample time was complete, the participant ramped up to the next velocity. The participant remained on the bike for the duration of the speed sweep from 8m/s to 12m/s.
The speed sweep was carried out across a baseline tyre and four other tyres. The baseline tyre was repeated at the end of the data collection to ensure there was no deviation from the first run.
Results: Tyre Performance and Power Loss Comparison
In the speed sweep, the PER was able to measure a noticeable difference between the five tyre samples. As seen in the graph below, there is a consistent offset between the tyres. Tyre 1 has the lowest power loss across all speeds and Tyre 3 had the highest power loss across all the speeds. Each of the tyres followed a similar trend, with greater power loss at higher speeds. Plotted lines of power loss vs road speed followed a similar offset between samples. Tyre 2 and Tyre 5 performed similarly together across all speeds.
Writing these observations in terms of efficiency: Tyre 1 was the most efficient and Tyre 3 was the least efficient across all the speeds. Tyres 2 and 5 performed similarly to each other. As the speed increased, so did the efficiency of the tyre, indicating that they all performed better at faster speeds.
Reducing Rolling Resistance for Marginal Gains
This study highlights the significant impact of tyre selection on rolling resistance cycling performance.
For professional teams, the ability to quantify and reduce these losses offers a clear competitive advantage. Selecting the optimal tyre can lead to meaningful improvements in cycling performance optimisation, particularly in high-stakes racing environments.
Optimise Your Cycling Performance
Optimising rolling resistance and system efficiency can deliver measurable gains at the elite level.
To quantify your equipment choices and reduce power loss, book a session on the Pedalling Efficiency Rig at Silverstone Sports Engineering Hub.