If you cycle commute, a loud horn can be very important because bells are too quiet to be heard inside vehicles.
Since I’ve experienced close calls, mostly close passes, in the past, I’m now really into cycling safely which is why I bought the Airzound horn and daytime safety bicycle lights. Mountain Equipment Co-op sells the horn for $19. I use it for dangers such as close passes and opening car doors. The horn is similar to aerosol horns except that it’s refillable with a tire pump up to 100 PSI.
It’s advertised to be 115 dB which is comparable to car horns. I have tested it to be 115.9 dB at 1 meter.
The horn is installed onto the handlebar of the bicycle with its air canister in the water bottle cage. If your handlebar is too thin, you can wrap it with duct tape. I installed it on the right side because I have a left handed bell for pedestrians. They have an option of attaching the canister to the bicycle frame with Velcro.
The horn has a volume control. From my testing, the canister holds enough air to last 8 seconds continuously at maximum volume and 25 seconds continuously at minimum volume.
When I used the horn for close passes, drivers often seemed surprised because they sped up slightly afterwards. They either didn’t expect me to use a loud horn, or didn’t even know that they were too close. Close passes is the main reason why I avoid busy streets. If I take the lane, drivers sometime honk.
I’m still learning how to react quickly and be able to use it at the proper time. It’s sometimes difficult to tell if a left turning driver notices you when you have the right of way.
If you want to see how effective the horn is, you can go to YouTube. They have lots of videos of cyclists using the horn for close calls.
The horn does have drawbacks which include build quality, reliability, and trigger location. The tube is UV sensitive. You can wrap it with tape to protect it from UV rays and scratches. It looks like volume is reduced by squeezing the tube. This may wear it out. I recommend never adjusting the volume and keeping it at maximum. They should have used an air valve instead. The weather must be at least -10°C for the horn to work which is rarely a problem in the west coast. When honking, you will lose braking power because you won’t be able to use the same hand to brake. It’s better to install the horn on the same side as the rear brake lever because most of the braking comes from the front brake.
If you cycle, my advice is to invest in a loud horn such as the Airzound horn. We need safer cycling.