Calculators5 min readUpdated: 2026-09-16
Impedance Break-Point
Definition
The impedance break-point is the critical tire pressure threshold beyond which additional inflation causes rolling resistance to increase dramatically due to surface vibration losses.
Detailed Technical Breakdown
Discovered through empirical on-road testing by SILCA CEO Josh Poertner, the impedance break-point represents the inflection point where tire casing deflection efficiency is overtaken by vibrational kinetic energy dissipation. On real-world roads, an over-inflated tire bounces over micro-roughness rather than conforming, deflecting the entire rider mass upward and dissipating significant wattage into human muscle tissue as heat.
Key Technical Specifications
- Inflection point: Rolling resistance decreases up to the break-point, then increases steeply.
- Vibrational losses (impedance) scale exponentially with surface roughness and speed.
- Tubeless tires lower the break-point pressure safely without pinch flat risks.
- Penalty for 5 PSI over the break-point can waste 15 to 25 Watts of rider output.
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