Optimal tubular pressure on the wooden velodrome: analysis of the Crr-pressure relationship, impedance loss phenomenon and compromise between rolling and lateral grip

The traditional heuristic associating higher inflation pressure with lower rolling resistance coefficient on wooden surfaces does not hold experimentally. Data published since 2018 by Bicycle Rolling Resistance Lab and AeroCoach document the existence of an optimal point below the tubular's maximum admissible pressure, whose crossing simultaneously penalises Crr and grip on banked corners. Quantitative determination of the optimal interval constitutes a relevant material component of performance in individual pursuit, kilometre time trial and sprint events.

Specificity of the tubular-wooden surface interaction

The Siberian pine (Pinus sibirica) used in the construction of a covered velodrome track is arranged in laminated slats 4-6 cm wide. Between adjacent slats a microscopic joint exists. The surface visually perceived as continuous and smooth presents, at velocities of 55-65 km/h, a succession of discontinuities on the order of 0.05-0.2 mm every 5 cm. An over-inflated tubular does not absorb these micrometric irregularities: it rebounds, and the rebound translates to quantifiable energy loss.

The phenomenon is termed impedance loss and has been documented by Bicycle Rolling Resistance Lab and AeroCoach through dozens of real-track measurements. The Crr curve as a function of pressure does not present monotonically decreasing behaviour: it exhibits a minimum between 8.5 and 10.5 bar depending on the tubular, the surface and the cyclist's mass.

Experimental shape of the Crr-pressure curve

Measurement on a Siberian pine surface velodrome (Continental Sonderklasse 22 mm, 74 kg cyclist) documents the following experimental profile:

The experimental minimum sits in the interval 9.5-10 bar. Elevation to 12 bar provides no benefit: it penalises 2.4 additional watts. Reduction to 8 bar penalises 1.3 W; to 7 bar, 3 additional watts. The minimum does not describe a flat plateau but a distinct parabola. Adoption of the manufacturer's maximum pressure as operational criterion constitutes a decision with quantifiable chronometric cost.

Correction by cyclist mass: adjustment equation

A 60 kg cyclist induces tubular deformation inferior to that produced by an 85 kg cyclist. Consequently, the experimental pressure optimum shifts towards lower values by 0.3-0.5 bar. The operational rule is synthesised in the following approximate expression:

Calculated values correspond to: 62 kg cyclist, 9.1 bar; 78 kg, 9.9 bar; 85 kg, 10.25 bar. The equation constitutes an operational approximation: each tubular presents its characteristic curve, whose experimental verification requires specific instrumentation.

Compromise between Crr and lateral grip on banked corners

Inflation pressure does not exclusively affect Crr on rectilinear trajectory. On 42% banked corners —standard geometry of the UCI Cat.1 250 m velodrome— the tubular operates under significant lateral load. An over-inflated tubular presents a contact patch of reduced width and lower lateral force generation capacity. In the extreme regime, the manifestation is slippage.

For individual pursuit events on continuous trajectory, this margin is rarely explored. For sprint events in keirin or 200 m flying time trial, the interaction occurs systematically. A sprinter seeking to maintain the black line on corner exit at velocities above 70 km/h requires a pressure 0.5-1 bar below the pure Crr optimum. The rolling penalty sits at 1-2 W; the gain in lateral grip may correspond to a full lap of clean line.

Operational recommendations by discipline

Thermal correction: cold-measured pressure versus competition pressure

The tubular experiences heating during roller warm-up prior to competition, with a characteristic pressure increase of 0.3-0.5 bar relative to the cold reading. If the target operational reference is 9.5 bar during competition, cold inflation pressure must be adjusted to 9.1-9.2 bar to converge on the desired value after warm-up. Systematic omission of this correction explains the empirical observation of superior performance in the second heat of the day relative to the first: the second heat is executed, without explicit planning, closer to the experimental optimum.

References: Bicycle Rolling Resistance Lab (2024). Track Tubular Pressure Study. AeroCoach (2024). Track Optimisation Report. Continental Reifen AG (2025). Sonderklasse Test Protocol. Debraux, P., Grappe, F., Manolova, A. V., & Bertucci, W. (2011). Aerodynamic drag in cycling. Sports Biomechanics, 10(3), 197-218.