There is no danger to others in biking without a helmet.
The helmet issue is mostly something to try to get at biking people, it is not a public health issue. That why all warning are worded along the line: “helmet prevent head injuries” (like knee pad limit knee injuries), and not “helmet improves general outcomes”.
Most studies agree that head injury absent a car strike are rare and are compensated by the long term benefits over the population. The most dangerous thing in a bike is the surrounding cars.
The helmet issue is mostly something to try to get at biking people, it is not a public health issue. That why all warning are worded along the line: “helmet prevent head injuries” (like knee pad limit knee injuries), and not “helmet improves general outcomes”.
Most studies agree that head injury absent a car strike are rare and are compensated by the long term benefits over the population. The most dangerous thing in a bike is the surrounding cars.