Road and Suspension

Road and suspension

OpenShaker guide › Effects

The effects that carry the road: Suspension bumps, Kerbs / rough road and Surface feel.

Suspension bumps

What you feel: the road through the seat. That means bumps, ripples, and a low hum that grows as the surface gets rougher.

How it works. This effect has several ingredients, and each preset uses a different mix:

• Road bed (Forza and Assetto Corsa EVO presets): a continuous low tone around 41 Hz. Its strength follows how fast the suspension is moving, so smooth tarmac is quiet and broken surfaces are louder. It has a slightly buzzy, square-wave character to match HaptiConnect, and plays above 1 m/s.
• Bumps (Trackmania):
  • A separate short thump for each wheel when that wheel's suspension moves quickly: 38 Hz at the front, 30 Hz at the rear.
  • Faster movement gives a stronger thump.
  • Each wheel thumps at most once every 0.04 s.
• Texture (Trackmania): a fine, low rumble (noise below about 40 Hz) that follows how busy the suspension is overall.
• Vertical-g thumps (fallback): when a game sends no suspension movement at all, a thump plays when the vertical g-force jumps suddenly. That is always the case in BeamNG, and in Forza while the car is in the air.

After a pause, a race start or a gap in the data, the effect starts its measurements over. Unpausing never plays a phantom bump.

Default in each preset:

Preset	Default	Level	Notes
Forza Motorsport	On	1.6	Road bed only: 41.2 Hz, following suspension speed, with a 50 ms hold. Per-wheel bumps and texture are off. In the air, a 45 Hz thump plays on vertical-g jumps over 12 m/s², at most every 0.1 s.
Forza Horizon 5/6	On	0.6	Road bed that follows suspension movement in metres, timed on the game's own clock, frame by frame (no hold). A band of rumble noise at 37-45 Hz is added. Bumps and texture are off.
Assetto Corsa EVO	On	1.0	Road bed from the game's suspension data, with a 50 ms hold. Bumps and texture are off.
BeamNG.drive	On	0.7	BeamNG sends no suspension data, so there are only vertical-g thumps: 45 Hz at a fixed level, on jumps over 12 m/s², at most every 0.15 s. Needs Motion Sim. The level has not been checked against HaptiConnect yet.
Trackmania	On	0.6	Per-wheel bumps plus texture, no road bed. Suspension is held while a wheel is in the air and settled after landings, so a jump does not turn into a burst of bumps.

Game data: each wheel's suspension travel (Forza Horizon uses metres), the vertical g-force for the fallback, and speed.

Strength slider: loudness of every part of the effect.

Tips:

• Assetto Corsa EVO: Advanced... → ACE suspension travel scale (m) (default 0.08) sets how many metres count as full travel. A smaller number makes the same movement count as more travel, so the road bed gets stronger.
• Trackmania: big jumps are handled by Landings. Small hops are left to this effect.

Code: SuspensionEffect in openshaker/effects/racing.py.

Kerbs / rough road

What you feel: the rattle of rumble strips and kerbs, rising in pitch as you go faster.

How it works. When the game reports that a wheel is on a rumble strip, a repeating wave plays. Its pitch climbs with speed, the way the ridges pass under you faster. It stops as soon as no wheel is on a strip.

The details:

• In Forza Motorsport the pitch is 1.25 Hz per m/s of speed: about 35 Hz at 100 km/h and about 69 Hz at 200 km/h. It is limited to 6-100 Hz.
• The effect also has a built-in rough-road noise, but the calibrated presets do not use it and no shipped preset plays it.

Default in each preset:

Preset	Default	Level	Notes
Forza Motorsport	On	0.3	A pure sine at 1.25 Hz per m/s, 6-100 Hz, at a steady level. Triggered by Forza's per-wheel rumble-strip flags.
Forza Horizon 5/6	On	1.0	A richer wave, 6-42 Hz, getting quieter as speed rises. It plays nothing in Horizon, because the game never sets the rumble-strip flag. You only hear it in the Demo.
Assetto Corsa EVO	Silent (level 0)	0	HaptiConnect's ACE plugin has no kerb effect. The game does send a car-wide kerb signal.
BeamNG.drive	Silent (level 0)	0	BeamNG sends no kerb data
Trackmania	Off	1.0	Trackmania sends no kerb data. Surface feel replaces it.

Game data: per-wheel rumble-strip flags (Forza), the kerb vibration signal (Assetto Corsa EVO), and speed.

Strength slider: loudness only.

Code: RoadEffect in openshaker/effects/racing.py.

Surface feel

What you feel: what the tyres are driving on, whether dirt, gravel, grass, ice, plastic or metal. You also feel water sloshing and splashing, and the roof scraping.

How it works. Trackmania reports which material each wheel is touching, and each material has its own texture. That texture is a band of rumble noise with its own depth and level. "Resonant" materials such as plastic, rubber and metal also add a tone. Among the wheels on the ground, the strongest noise texture and the strongest tone are played. They can come from different wheels.

It grows with speed: nothing below 2 m/s, reaching full strength at about 150 km/h.

Water and roof:

• In water (more than 5 % submerged): a very low slosh (below about 18 Hz) that grows the deeper you are. It keeps at least 20 % strength even when slow.
• Hitting water faster than 5 m/s (18 km/h): a 22 Hz splash thump, stronger the faster you hit.
• Roof scraping the ground: a scrape noise (up to about 85 Hz), with at least 30 % strength even when slow.

Surface textures. "Depth" is the noise's brightness: a lower number means a deeper rumble. "Level" is how strong it is.

Group	Materials (depth Hz, level)
Smooth, nothing added	Asphalt, WetAsphalt, Tech, TechGround, TechSafe
Smooth, barely there	TechArmor (0.02), Concrete (0.03), RoadSynthetic (0.05), WetPavement (0.05), Pavement (0.06)
Stairs	PavementStair (40, 0.3)
Loose	Dirt (35, 0.55), DirtRoad (35, 0.5), WetDirtRoad (30, 0.5), Gravel (45, 0.6), Sand (28, 0.45), Rock (50, 0.5), Stone (50, 0.45)
Soft	Grass and Green (22, 0.4), WetGrass (20, 0.35), Forest (25, 0.45), Wheat (20, 0.3)
Slick	Ice (70, 0.05), RoadIce (70, 0.04), Snow (40, 0.15)
Wood	Wood (45, 0.3), SlidingWood (45, 0.25)

Resonant materials add a tone:

Material	Tone (Hz, level)
Plastic	62 Hz, 0.3 (on top of a 50 Hz / 0.15 rumble)
Rubber	55 Hz, 0.3 (on top of a 45 Hz / 0.2 rumble)
SlidingRubber	55 Hz, 0.25
RubberBand	58 Hz, 0.3
Metal	48 Hz, 0.3 (on top of a 60 Hz / 0.1 rumble)
ResonantMetal	44 Hz, 0.4
MetalTrans	50 Hz, 0.25
MetalFence	46 Hz, 0.35
TechMagnetic	70 Hz, 0.15
TechSuperMagnetic, TechMagneticAccel	70 Hz, 0.2

Default in each preset:

Preset	Default	Level	Notes
Forza Motorsport, Forza Horizon 5/6, Assetto Corsa EVO, BeamNG.drive	Off	0.5 if ticked	No surface data, so nothing plays even if you tick it
Trackmania	On	0.5	Replaces Kerbs / rough road

Game data: the material under each wheel, which wheels touch the ground, water depth, roof contact and speed. Only Trackmania sends these.

Strength slider: loudness of everything in this effect, including the splash.

Code: SurfaceEffect in openshaker/effects/trackmania.py.

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Next: Grip and braking

See also: Effects overview · Trackmania