Check out AirZound, it’s a bike pump rechargeable horn.
Companies also make battery powered ones that sound like a car horn.
Finally, there are impact wrench driven train horns that are over 100dB loud for when you just can’t get their attention (WARNING: hearing damage guaranteed).
I used to have one wedged between the brake and gearshift levers of my bicycle, so I could hit the button with my thumb, it was very handy.
Check out AirZound, it’s a bike pump rechargeable horn.
Companies also make battery powered ones that sound like a car horn.
Finally, there are impact wrench driven train horns that are over 100dB loud for when you just can’t get their attention (WARNING: hearing damage guaranteed).