What Is Shock Aeration

Shock aeration occurs when the oil and nitrogen gas inside a shock absorber mix and foam, causing the shock to lose all damping power. Whenever a shock moves, the piston and valve move through the oil. In situations when the shock cycles a lot, such as long trips offroad or on rough roads, that movement through the oil can cause aeration.

A shock gets its damping ability from the valve attached to the piston, which slows the movement of the piston through the oil. During aeration, the foamed oil and gas mixture allows the piston to flow freely and provides no damping (see our FAQ: What does a shock do?)

Nitrogen gas was added to shocks a long time ago to reduce aeration and allow shocks to operate for longer time periods in higher heat (see our FAQ: What's the difference between an oil shock and a gas shock?). Higher gas pressure can reduce aeration in shocks along with other technical advancements like specialized valves, external oil reservoirs and better heat dissipation.