— La scienza della pressione — per la bicicletta
Campionato di precisione

La
Pressione

Passion for Cycling
Science-based tyre pressure
recommendations for road & gravel
Metric · bar · v2.0
Display units
Primary output in bar · psi shown as secondary
Front tyre — recommended
—bar
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Rear tyre — recommended
—bar
—
Difference
—
bar · front → rear
Optimal Crr
—
rolling resistance ×10⁻³
Watt penalty
—
vs optimal ±0.3 bar
Comfort
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Rolling speed
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Puncture risk
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Rolling resistance vs pressure
Deformation Vibration Total Crr
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La guida tecnica

The Science
Behind the Numbers

Why "harder is faster" is mostly wrong — and what the physics actually says about tyre pressure, rolling resistance, and contact patch dynamics.

Principle I

Two Forces in Conflict

Tyre rolling resistance is not a single force — it is the sum of two competing loss mechanisms that pull in opposite directions as pressure changes.

Tyre deformation loss occurs because rubber is not perfectly elastic. Each time the contact patch flattens under load and then springs back as the wheel rotates, energy is lost as heat. Higher pressure reduces this deformation — on a perfectly smooth surface, a harder tyre genuinely rolls faster.

Vibration loss works in the opposite direction. On any real road surface, microscopic and macroscopic texture causes the tyre to bounce. A rigid, over-inflated tyre cannot absorb these impacts — it transmits them to the bike and rider, who then waste energy re-accelerating after each tiny deflection. Lower pressure damps this vibration.

The optimal pressure is where the sum of these two losses reaches its minimum — and this minimum shifts dramatically depending on surface roughness.

Principle II

Width Changes Everything

A wider tyre run at the same pressure as a narrower one carries a much larger volume of air relative to its load. The contact patch area is determined by the load divided by the internal air pressure — so a 32 mm tyre at 5.0 bar and a 25 mm tyre at 5.0 bar have the same contact area, but the 32 mm patch is shorter and wider.

This shorter, rounder contact patch completes its deformation cycle more gradually as the wheel rotates, dissipating less energy per revolution. This is why modern road cycling has moved decisively toward 28–32 mm tyres at lower pressures: they are measurably faster on typical road surfaces than the old 23 mm + 7–8 bar orthodoxy.

For gravel and rough roads, the effect is even more pronounced. A 40 mm tyre at 2.5 bar can absorb surface irregularities that would bounce a 25 mm tyre off the ground entirely.

Principle III

Front and Rear Are Different Wheels

Most cyclists inflate both tyres to the same pressure. This is almost always wrong. The rear wheel carries approximately 55–60% of the combined rider-and-bike weight, while the front carries only 40–45%. Running equal pressure means the front is overinflated relative to its load.

An overinflated front tyre provides a smaller contact patch and reduced grip — exactly where you need grip most for braking and steering. Running the front 0.3–0.5 bar softer than the rear is the correct approach, and is standard practice among professional riders.

The weight split also varies by riding position: aggressive aero positions shift more weight forward; upright touring positions shift it back. Adjust your split accordingly using the calculator above.

Tubeless tyres can be run 0.5–1.0 bar lower than equivalent tubed setups on both wheels, since pinch flats are eliminated. This is a free performance and comfort gain — take it.

Quick Reference — Pressure Ranges by Category
Road racing · 23–28 mm
5.5 – 7.5 bar
Smooth tarmac. Tubeless: subtract 0.5–0.8 bar. Front always softer than rear.
Endurance road · 28–35 mm
4.0 – 6.0 bar
Mixed surfaces, comfort matters. Lower end for rough roads and heavier riders.
Gravel · 35–50 mm
2.0 – 3.8 bar
Tubeless strongly recommended. Go as low as possible without rim strikes or burping.
Cobbles / pavé · 27–30 mm
4.2 – 5.2 bar
Paris-Roubaix territory. Vibration loss dominates — low pressure is genuinely faster.
Bar ↔ PSI Conversion
BarPSITypical use
2.029Gravel / very wide tyres
2.536Gravel tubeless minimum
3.044Wide gravel / MTB
3.551Endurance 40 mm+
4.058Endurance 32–38 mm
4.565Cobbles / endurance 28 mm
5.073Road 28–32 mm standard
5.580Road 25–28 mm
6.087Road 25 mm / racing
6.594Road 23–25 mm racing
7.0102Road 23 mm maximum
7.5109Track / tubular only
8.0116Track sprinting
Fine-Tuning Protocol
1.Start with the calculator's recommended pressure for your weight, width, and surface.
2.Ride a known section of your typical road. Note comfort and feel — particularly over rough patches.
3.Drop pressure in 0.2 bar steps until the ride feels noticeably harsher or tyres feel squirmy in corners. The step just before is your lower bound.
4.Raise pressure in 0.2 bar steps until you notice vibration or buzzing through the handlebars. The step just before is your upper bound.
5.Your optimal is typically in the lower third of that range for most road surfaces. Re-check when changing tyre brand or batch.
6.Check pressure before every ride — tyres lose 0.1–0.3 bar overnight through normal permeation, more through the tube/valve.
Common Bike Weights — For Total System Weight Calculation
Bike typeTypical weightRange
Road race (UCI legal min)6.8 kg6.8 – 7.5 kg
Road endurance / sportive8.5 kg7.5 – 10 kg
Gravel / all-road9.5 kg8.5 – 11.5 kg
Cyclocross8.0 kg7.5 – 9.5 kg
Touring / randonneur11.5 kg10 – 14 kg
City / commuter13.0 kg11 – 16 kg
Electric road bike14.0 kg12 – 18 kg
Electric cargo / urban25.0 kg20 – 35 kg
Mountain bike (hardtail)11.0 kg9 – 13 kg
Mountain bike (full-sus)13.5 kg11 – 16 kg
Track / velodrome7.5 kg7.0 – 8.5 kg
Triathlon / TT8.5 kg7.5 – 10 kg

Add accessories: saddle bag ~0.3 kg, bottles ~0.8 kg each, lights ~0.2 kg, pedals ~0.3 kg. Loaded touring adds 5–20 kg.

How to Use This Table
→Weigh yourself and your bike separately for the most accurate result. A bathroom scale works fine for the bike — hold it, step on the scale, subtract your own weight.
→If you cannot weigh the bike, use the typical figure from the table and add 0.5–1.0 kg as a margin for accessories.
→For loaded touring and bikepacking, add the full pack weight to the system weight — heavy panniers significantly increase optimal rear pressure.
→Rider weight should be your typical riding weight including kit, helmet, shoes, and any food or water you carry at the start of a ride.
→Every 10 kg of total system weight typically shifts optimal pressure by approximately 0.3–0.5 bar depending on tyre width.
Scientific & Technical References
Peer-reviewed · Ergonomics, 1999
Influence of Tyre Pressure and Vertical Load on Coefficient of Rolling Resistance and Simulated Cycling Performance
Grappe, F., Candau, R., Barbier, B., Hoffman, M.D., Belli, A. & Rouillon, J.-D.
Seminal laboratory study establishing the non-linear relationship between tyre pressure and Crr. Showed Crr decreasing 62% from 1.5 to 12 bar, described by a hyperbolic function. Foundation for modern pressure modelling.
View on ResearchGate →
Field research · Bicycle Quarterly, 2009–2016
Suspension Losses: Real-Road Tyre Performance Testing
Heine, J. — Bicycle Quarterly Vol. 8 No. 1; Vol. 5 No. 1 & 3; replicated by Poertner, J. (SILCA), 2016
Pioneering real-road roll-down tests demonstrating that suspension losses cancel hysteresis gains above a threshold pressure. Showed higher pressures do not yield faster speeds on real roads. Results independently replicated in 2016.
Suspension losses confirmed →
Field research · Rene Herse Cycles, 2015 & 2019
Tire Pressure Data and Details; Myth: Higher Pressure Is Faster
Heine, J. — renehersecycles.com
Detailed real-road datasets across multiple tyre types and widths. Demonstrates the "break-point" pressure concept and explains why moderately high pressures can be slower than both lower and higher pressures on smooth pavement.
Read the analysis →
Industry research · SILCA, 2015–2024
Rolling Resistance, Impedance, and the Breakpoint Pressure Calculator
Poertner, J. — SILCA LLC. Algorithm built from 4,000+ real-world optimisations with WorldTour and Olympic athletes.
Introduces "impedance" as distinct from Crr: the energy cost of lifting bike and rider over surface texture. Defines breakpoint pressure as the inflection where impedance losses overtake deformation gains. Basis of the SILCA Pro Calculator.
Read the series →
Independent lab database · bicyclerollingresistance.com
Rolling Resistance Test Methodology and Tyre Database
bicyclerollingresistance.com — ongoing, 2014–present
Largest independent tyre Crr database. Tests at four pressures per tyre, 42.5 kg load, 28.8 km/h on a controlled drum at 22 °C. Useful for comparing tyre models; note drum tests measure deformation losses only, not suspension losses.
See test methodology →
Technical review · Rene Herse Cycles
Tire Testing: Lab vs. Real-Road — Why Drum Tests Are Misleading
Heine, J. — renehersecycles.com
Critical analysis of steel drum test limitations — the convex drum pushes deeper into supple tyres than a flat road would, and the absence of a rider eliminates suspension losses entirely. Essential context for interpreting any lab-based Crr figure.
Read the critique →
Technical review · SILCA, 2024
Tire Pressure Calculator Explained — Methodology and Breakpoint Theory
SILCA LLC — silca.cc
Explains how casing losses and surface impedance interact to create a pressure optimum unique to each surface type. Confirms that every tyre tested gets faster with increasing pressure until a breakpoint, then slower — even on very smooth surfaces.
Read the methodology →