It is generally recommended to replace a motorcycle helmet after it has been dropped, even if there are no visible signs of damage. The impact from a drop can compromise the structural integrity of the helmet, even if the exterior appears undamaged. The foam liner inside the helmet, which is responsible for absorbing impact energy, can be compressed or damaged in a way that is not visible to the naked eye.
The general rule of thumb is that if a motorcycle helmet is dropped from a significant height (usually considered to be around 3 to 4 feet or 1 to 1.2 meters), it should be replaced. This guideline applies regardless of whether the helmet was in use during the drop or if it fell from a stationary position.
Even a seemingly minor drop can affect the helmet's ability to provide adequate protection in the event of an accident. Helmets are designed to absorb and disperse the forces of an impact, but once they have experienced a significant drop, their ability to protect your head may be compromised.
It's important to prioritize your safety and invest in a new helmet if your current one has been dropped. The cost of replacing a helmet is small compared to the potential consequences of wearing a compromised helmet during an accident. Always follow the manufacturer's recommendations regarding helmet replacement and consult the specific guidelines provided with your helmet.