Autumn usually brings a flurry of articles about being well lit up when cycling, but I think an overlooked area of cycling safety is the ability to warn cars of your presence on the road. The bike bell is very important for pedestrians but useless for that car door about to open in front of you or the car who hasn’t seen you on a give way. I have tried several techniques to catch the unattentive motorists ear, starting with loud (and mostly polite) shouting which is usually only done under extreme circumstances, when it’s too late i.e they have already pulled out in front of me. I did have an impressively loud air-horn mounted on my bike for a year or two and they were extremely good for more pre-emptive situations, but only when I remembered to pump it up with my bike pump on a regular basis (at least weekly or after one blast). Unfortunately there were too many times when I had not got around to pumping it and was very disappointed when depressing the lever to have a frail dying goose noise come out instead of the expected 100+ dB freight train I was desperately needing.
I upgraded to a 12V battery connected to two old car horns via a relay, all mounted on a front rack, and a pushbutton mounted at the end of my J bar (bar ends). The 2A-hr sealed lead acid battery lasts six months or so before needing charging, depending on how many blasts it gets. It has saved me from dangerous encounters on many occasions, alerting cars to the fact they haven’t seen me.
It seems to go in cycles, with several weeks typically passing with no tooting required, then there’ll be three blasts needed in the space of five minutes. Occasionally I still end up frustrated when the car driver frantically looks around for the car or truck they’re about to hit and still manages to look right through me. This most often happens with a left moving car cutting me off when I’m in their blind spot. Overall it gives me a great sense of empowerment on the road and I feel a lot less like a victim waiting to happen, mainly because it’s so easy to give a friendly toot which can make all the difference to my safety. It particularly makes an improvement in a few ‘high alert’ areas around Christchurch (e.g. Riccarton Road) where my thumb is hovering above the button for long periods of time.
I highly recommend a decent horn on any commuting bike – well worth the extra few grams of weight. Build your own up or they are easy to find online if you want to spend a bit more money. I’m sure you could make it look more beautiful than the one on my bike but I intentionally like an ugly bike for it’s anti-theft benefits.