What is what does it mean when a biker taps his helmet?

Here's what it typically means when a biker taps their helmet:

A biker tapping their helmet usually signals a warning to other riders about a hazard ahead. The most common meaning is that there is police%20or%20other%20law%20enforcement presence ahead, such as a speed trap or officer on the side of the road.

However, the signal can also be used more generally to warn of any%20hazard in the road, such as:

• Potholes
• Gravel
• Debris
• Accidents
• Stopped vehicles

It is a quick and easily recognizable way for riders to communicate without using verbal communication. Note that helmet tapping can%20be%20subjective, with meaning changing on a per-area basis.