Loud Bicycle: Car horn for your bike

An outstanding Kickstarter project - a bike horn that is as loud as a car horn!

Cycling in traffic can be frightening and dangerous. The Loud Bicycle horn prevents accidents by alerting motorists with a familiar sound. The safety benefits of the horn give more people the confidence to travel by bike.

How does it work?

Drivers react to car horns before they even know where the sound is coming from. A driver that gets beeped at while backing out of a driveway for example, will immediately brake. These kinds of reflexive reactions are perfect to keep cyclists safe. Some motorists don't realize that their driving habits can be dangerous for cyclists. Drivers will learn to be more aware of cyclists after a Loud Bicycle horn is honked at them.

I want a loud horn for pedestrians.

Loud Bicycle: Car horn for your bike

• [Hanglyman]

  Why stop there?
  http://boingboing.net/2012/05/08/train-horn-attached-to-bicycle.html

  • [Lobster]

     That’s what I’m talkin’ about!

• [Navin_Johnson]

  Awesome. I was actually thinking about the possibility of this just yesterday while biking to work. 

• [Wreckrob8]

  I want a car horn for pedestrians and fast and slow walking lanes strictly enforced and a car horn for tube users to honk people out of the way who stand on the left side of escalators.

  • [acidrain69]

    Done. https://www.google.com/search?q=air+horn&hl=en&safe=off&tbo=u&tbm=isch&source=univ&sa=X&ei=_OXMUP-iHovC9gT7r4DgCQ&ved=0CFQQsAQ&biw=1920&bih=929

  • [Nathan Hornby]

    People standing on the left hand side of the escalators… I hate those people.

    • [tudza]

      I think people in Japan stand on the left to ride.

      • [Nathan Hornby]

        Well that’s just silly.

        • [Ipo]

           I’m confused. 

      • [benher]

        Fun Fact! In Osaka/west Japan we stand on the right. Only Tokyo people stand on the left. 

  • [Labbit]

     Something like this perhaps?

    http://www.youtube.com/watch?v=kQd6vlF0f2k

  • [Rindan]

    We have these in Boston.  I actually saw someone use it today.  A dude was crossing the street and a car tried to plow through him when making a right on red.  The man bellowed at the top of his lungs, drowned out all other car noises, “Fuck you asshole!” (phonetically, it sounded more like “Fahk you asshooole.”)

• [Scott Rubin]

  “Drivers react well to car horns” 

  Why don’t you come pay us a visit here in NYC?

  • [Jonathan Lansey]

    haha … _untested_ in NYC, but I bet it will still work.

• [Michael Smith]

  Problem is the ear damage you get from the horn. Then you need ear protection and you have a safety problem again. I am a bike commuter and I have built things like that at different times. I reckon that abusive words are worth a few db of sound intensity anyway.

  On a related note I once saw an older guy in an electric wheelchair struggling through a heavy crowd in a local shopping center. It turned out that he still knew how to wire things up because he had a car horn on that thing. Man did those pedestrians scatter.

  • [dragonfrog]

    If you’re using it often enough that you’d get ear damage, then either you’re using it wrong, or you’re cycling in such dangerous conditions that ear damage is the least of your concerns.

    If I had one, I’d probably use it wrong, because how much fun would that be?

• [capawesome]

  So people are now asking to be run over?

  • [dragonfrog]

    Ooh, an internet tough guy.  Specifically, an internet tough guy threatening vehicular manslaughter on a thread about cycling safety.

    How surprising.

    • [capawesome]

       [whoop whoop Maury audience noises]

    • [Petzl]

       Capawesome, YOU ARE NOT THE FATHER

• [beforewepost]

  What? 115 dB ain’t enough? 

  http://www.modernbike.com/itemgroup.asp?igpk=2126175349&TID=367&gclid=CNLulIypnbQCFUjZQgodEGMAkg

  • [vonbobo]

    wow, smaller landfill, cheap, nice!
    However, it is missing the key dual tone technology, and the Dyson Jr commercial spot. 

  • [kartwaffles]

     Yep. AirZound horns are great. Not knocking the electric one linked to in this thread, but it’s hard to beat a battery-free horn at 1/3 the price of the kickstarter horn. Use any beverage bottle for an air reservoir. Fill it up with your bike pump. Louder than hell, too.

• [fenester]

   That’s what came to my mind too.

• [Airplane]

  airzounds works great, $20 at LBS

  • [Ian Wood]

    I used one of those to great effect while riding in NYC. Made a jaywalking Japanese businessman do a full-on Jerry Maguire in a crosswalk once.

    • [Aloisius]

       Why would you honk at a pedestrian? They have right of way.

      • [Ian Wood]

        I suppose I could’ve just plowed into him, but it seemed best to alert him to my presence.

        • [Funk Daddy]

          Probably best to just brake if possible. The way all vehicles should. I think that’s what Alosius was indicating.

        • [dragonfrog]

          That’s what horns are for – warning of danger.  Danger such as “I don’t have enough room to brake for you, so you’ll have to stop despite having the right of way.”  You can say sorry afterward, since everyone will hopefully be uninjured and capable of speech.

          If it’s possible to brake, then indeed, n need to honk.

        • [Funk Daddy]

          I was only re-iterating the other guy, rules of the road are tattooed to the underside of my eyelids.

      • [Wreckrob8]

        I dunno. A bike nearly ran straight into me a few days ago as I was crossing a quiet London side street early in the morning. Of course, I was only listening for cars and not looking for bikes in a familiar local street. A lot of swearing by the cyclist woke me up in time. Totally my fault.

        • [miasm]

          perhaps an audio loop of engine noise?
          I know those bloody electric cars could use some.
          Or maybe I’ll try and just start looking. ;3

      • [Jonathan Peterson]

         ”jaywalking” – no right of way.

        • [Funk Daddy]

          Right of way is not a right and most sets of codified traffic laws maintain that a pedestrian where they are not supposed to be must still be observed and avoided, even if it means (shudder) braking.

          I’m not defending careless behaviour I’m just writing against the oft-perceived notion that someone with right-of-way is not legally bound to give it up to avoid harm to another. They are.

          A motorists/cyclists decision to proceed with just a warning when the option to stop or slow would have reduced harm can be justifiably found negligent. Likewise a pedestrian that is oblivious is partly responsible for their own harm when they err or choose to err.

          Safe road behaviour has little to do with right, rights or wrongs.

        • [Jonathan Peterson]

          Ian Wood honked at a pedestrian who was breaking the law, he also successfully avoided hitting him. Had made no effort to avoid the pedestrian he would have been clearly negligent.  But he was clearly in the right to use a horn to warn the pedestrian, who was endangering both of them by breaking the law. By alerting the pedestrian to his presence, he also increased the safety for BOTH of them.

        • [Funk Daddy]

          Your post has no information.

• [spacedmonkey]

  I totally need one of these.

• [Navin_Johnson]

  I’ll be the first to pay for one that plays La Cucaracha.

• [Gulliver]

  Judging by how often motorists try to Easy Rider my ass, I need one that shoots plasma bolts.

  Kneel before Schwinn!

  • [Navin_Johnson]

     ”Easy Rider my ass”

    Love this.

• [JohnQPublic]

  The guy starts telling the story about his friend Jen getting hit by a car and they fade to the image of a Ghost Bike – which is a bike painted all white and parked next to the location of the accident as a temporary memorial to mark a fatality involving a cyclist at that location.  However, the guy says Jen made it out of the hospital… which is great, but that makes the use of the Ghost Bike completely wrong and bad marketing as it uses the whole “You’ll die without this product” tactic.

  • [Jonathan Lansey]

    It was difficult to present the gravity of the situation without making the video too heavy. That particular bike is a memorial to a friend of a friend that was killed earlier this year at MIT (link below), an extremely sad story as they always are.
    http://tech.mit.edu/V131/N60/kyaw.html

    • [Funk Daddy]

      Sorry for your friends loss and yours.

       I can say as someone who knows that if that truck in the article was turning right off Mass onto Vassar  toward Main then the product you have there is one of the few things that may have changed that outcome. 

      It also could have possibly made a difference if the truck was turning left and this was a mid intersection collision. I did not read further than your link.

• [winkybb]

  I commute bike bike every day (about 25km each way into Vancouver). In spite of frequent transgressions, I’ve given up on trying to “correct” motorists, pedestrians and dog walkers etc, when they do things that place me in danger. The rights and wrongs are irrelevant. Any cyclist’s attempt to express displeasure with, for example, a car running them off the road or an off-leash dog running infront of them, will only be met with abuse. It is just the way it is. 

  Cyclists are almost universally despised by other road users. I just cycle with extreme politeness. I ride assertively where warranted but I no longer yell, gesture, slap on the hoods and/or trunks of cars etc. I just avoid the hazards  smile and continue on my way. I am much less stressed by not attempting to change the things I can’t affect Aggressive cyclists actually just make it worse. this “invention” will achieve nothing other than make everyone angry.

  I have chosen to preserve my inner calm and simply move along….much happier. “Serenity Now!”

  • [Gulliver]

    Individual rebukes are indeed a big gamble. I’m very cognizant that when I’m riding to work and school, I’m all but helpless against any driver that decides to try to kill or maim me. And let’s be clear: Whether that’s their explicit goal or not is irrelevant when they’ve chosen to play chicken with someone while they’re in a two-ton loaded weapon and I’m on a leg-powered aluminum frame. It’s the equivalent of if they’ve got a shotgun and body armor, and I’m in shorts and a t-shirt. The road is indeed an example of an armed society is a polite society, to the armed citizens. To the unarmed citizens, it’s a goddamn skeet shoot and we’re the fair game. I’m for anything that actually levels the playing field, but I doubt this will accomplish that.

    Ultimately, the only effective solution I can see is to make swiping a cyclist as taboo as swiping a pedestrian. In the mean time, I’m careful and I carry a licensed concealed firearm, which I practice with on the range twice a month, in case anyone does decide to follow me with the intent of causing harm.

    • [winkybb]

      I feel that carrying a concealed firearm is so far beyond any reasonable and rational response to the dangers of cycling in traffic that I don’t know where to begin. We agree on nothing.

      • [dragonfrog]

        I was just going to say the opposite – that’s the only argument for legalizing concealed firearms, against which I have a hard time bringing my usual arguments – not that I don’t believe them to be just as true, but because I have so much more emotional investment.

        My wife and I have both been assaulted by motorists while we cycled – me with the car itself, while my wife had a motorist throw a bottle at her head.  In both cases if the assault had connected, there would have been a serious likelihood of our dying.  If it were known that a large proportion of cyclists carried guns, I seriously doubt either of us would have been thus attacked.

        • [Antinous / Moderator]

          Why concealed then? Wouldn’t you be better off with an M41A pulse rifle, ten millimeter with over-and-under thirty millimeter pump action grenade launcher, slung over your shoulder?

        • [Funk Daddy]

          If it were known that a large proportion of cyclists carried firearms your doubts would be removed. 

          They would be attacked regularly for/and robbed of their weapons.

      • [Gulliver]

        Actually, the gun is more for when I’m riding where there is no traffic. I have a road bike and like to ride on country roads where some young alpha male may decide I’m roadkill. Mind you I consider the possibility mildly remote, but definitely within the realm of possibility. And if I am targeted, I want something that will scare the homicidal maniac off. I wouldn’t fire the gun in traffic lest I hit another motorist. But if someone tries to put me in a wheelchair or an early grave, I intend to fight back while I memorize plates and seek cover.

        Other precautions I’m working on include a wifi camera to mount on my handlebar and tether to my phone to store a few dozen hours of running live footage at just high enough res that assailants and vehicles can be ID’d.

        I don’t plan on ending up a pancake, and whatever keeps my bones intact is a rational response in my book.

    • [foobar]

      It takes two to play chicken.

      • [Funk Daddy]

        You are right. 

        Some people mistake the meaning of the word “right” in right-of-way and stupidly act as though killing or dying is the proper response to having been wrongly relieved of their right-of-way. Gulliver may not be one, but he certainly has a similar rationale if he believes there is a game of chicken on, ever.

        • [Gulliver]

          Bad choice of word. Obviously I’m not going to play chicken when I’m on a bike and they’re in a car. I’m not going to play chicken period, because I’m not a pinhead.

          Unfortunately, if someone in a car or truck decides to “play” with me, I have very limited ability to outrun them on a bike and better hope there’s somewhere I can go off road that they cannot (which is not always the case on the backroads of rural Texas). There’s a massive power-imbalance between me on my bicycle and a motorist. And while I, humanist that I am, believe most people are basically decent enough not to hunt others for the “sport” of it, it’s the occasional exceptions that I plan to be as prepared as possible against.

          My other options are give up riding my bike for fun and cheap healthy transport, or let myself be a soft target, neither of which I have any intention of doing. If you think I’m nuts or reckless for that, I can live with that :)

        • [Funk Daddy]

          It is always possible to get off the road be it gently or otherwise.

          The situation you describe most often presents itself to your back. I doubt you have the wherewithal to predetermine the attack vector of a vehicle approaching from the rear quickly and accurately enough to deploy and fire a weapon effectively.

          Where it is otherwise, if you are still on the road while fully aware you are in combat then you are effectively seeking it. 

          The situation you describe is ludicrously uncommon even in Texas, except where someone believes being passed closely or honked at would give them cause to brandish a weapon i.e. to escalate. Seeking it. 

          The cowboys you describe are more likely to take you up on the engagement if you brandish. After all, if they kill you then they are innocent, you threatened them and they did what they had to. Same story you would give. You’d both be wrong.

          Ludicrously uncommon. You are trying to dodge the raindrops to avoid using an umbrella. In order to justify the weapon you favour and pretend to need.

          I’m a Texan born and bred and a career cyclist. The people on the backroads who might, uncommonly, seem to you aggressive would simply drive away if you slowed enough to put up a hand without a finger upraised. You are seeking otherwise.

  • [Susan Jones]

    I’m not despised.   I know lots and lots of cyclists who aren’t despised by most other road users, either…  Perhaps a lot of your stress came from assuming you were being despised?   I do agree that the rights and wrongs are irrelevant and that drivers can easily launch into abuse but… far more often I’ve had overt acts of respect and kindness.  

    • [winkybb]

      Sure you’re despised. Just read the vitriol that spews forth in any discussion on cars Vs cyclists on the interwebs. You are despised for running red lights, for riding on the sidewalk, not riding in the gutter and for wearing lycra.

      I’ll acknowledge that my “almost universally” characterization is hyperbole, but is the overt acts of hatred and aggression that stick in one’s mind. I actually agree that most other road users are actually pretty good.

      • [Navin_Johnson]

         Yep, discriminated against definitely.  This is my new favorite piece on the whole thing:

        http://www.bicyclelaw.com/blog/index.cfm/2012/12/5/Confronting-the-Scofflaw-Cyclist

        • [winkybb]

          That’s a great piece. Highly recommended.

  • [Jonathan Roberts]

    I agree. One of the things you have to consider when cycling is that yelling and slapping on people’s hoods would be considered road rage if done by a car driver. As cyclists we are more vulnerable on the road but it is easy to be perceived as more aggressive or intrusive of people’s space if we react. Still, where I live in China no amount of honking, gesticulating or anything else would do much – even buses jump red lights (fast, and with no lights on at night if they don’t have passengers), there’s literally no lane discipline and cars drive on the sidewalk if they feel it will give them five seconds’ advantage. This may be my last post…

  • [Funk Daddy]

    Someone using a product like this to correct behaviour is using it incorrectly. You are correct regarding right and wrong, expressions related to same and where these rate. 

    This product if used correctly would be deployed rarely if the user is also using the road correctly. Since it has the potential to alert a road user that is beyond the reach of bells or voice it can be a benefit in some very specific but too common scenarios. Many cyclists are standing stock still or nearly stopped at an intersection when the number one most deadly situation arises. Vehicles making right turns slowly and legally.

    • [winkybb]

      Running down a stationary cyclist when making a right turn isn’t legal is it? Please tell me it isn’t.

      • [Funk Daddy]

        Look up right hook, and no. Passengers on an airplane may die when it crashes, but that does not necessarily mean the pilot did something illegal. You follow?

• [Susan Jones]

  A nice idea — what’s it made of?  
  For those who can’t cough up $95, for less than $25 an airzounds horn will work and there are no batteries; it’s an air horn.   IN my experience it works better than a car horn because it’s all kinds of loud but different.  I use it when I sense somebody not seeing me, not to be aggressive, winkybb.   (But then, I never slapped hoods and am almost always polite.)  
      I used mine today at a four way stop after watching one car wait patiently for the fellow who’d preceded him to go, then go anyway… and I realized that the middle aged fellow was highly engaged in, oh, something more interesting in his hand (I hope it was electronic) and was just sitting there at the intersection in his own little world.    Unfortunately, these are exactly the people who “snap out” of that state and hurry forward having not seen the “gorilla” (the unexpected) when they were only looking for cars… so I proceeded with caution, and then remembered that I had a horn and gave it a   toot when I was almost across (so he woudln’t have time to hit me if he thought I was behind him and just screamed forward).   He snapped to attention as I shrugged at the stopped car driver facing me waiting  his turn… and he gave me an affirming nod… I seriously doubt anybody was rendered angry unless it was at Mr. Handy.  
      My air horn tends to suffer from the weather in a year or so… I’d love something not made of cheap plastic.

• [Wayne Bonnet]

  A horn may be safe for warning a driver if you have lots of advance knowledge that someone is going to, say, back out of a driveway into your path.  But if a car is putting you into real danger, nine times out of ten you want to be squeezing your brakes, not reaching for a horn.

  My solution is to have my front brakes adjusted to be extremely squeaky.  This works remarkably well.  If I need to stop normally, I just use the rear brake preferentially.  If I need to stop fast, I am squeezing both brake levers hard, and the screech it makes gets everybody’s attention… much more than a car horn does.  I don’t have to do this often, only when put into real danger.

  Admittedly, this was a serendipitous result of being unable to adjust my brakes to be quiet.  It just took me some time to learn how to use them properly.

  Most bike mechanics should know how to introduce a squeak to your brakes… they may give you a funny look when you make the request though.

  • [Cowicide]

    if a car is putting you into real danger, nine times out of ten you want to be squeezing your brakes, not reaching for a horn.

    How about hooking up the horn to go off whenever one’s anus clinches?

    [hawwwnk!!!]

    • [Antinous / Moderator]

      You’ve been watching my XTube channel again, haven’t you?

  • [Funk Daddy]

    I’ve got two words for you. Right Hook.

    In a Right Hook (maybe a left hook in some places) it is too late to brake and if you can’t alert the vehicle to your presence or the presence of your bike trapped in a wheel well then you are fucked, dead or injured seriously.

    This product can definitely save a life in that situation. I can definitely show you deaths that may have been averted, but you have the google too.

    Also, your squeak, it is trumped by my yell. We all come with horns, but this one can penetrate the glass and steel cage.

    • [Wayne Bonnet]

      Yelling is effective too, but not nearly as loud as my squeaky brake.  My squeaky brake definitely penetrates the glass and steel cage, and to a driver it sounds quite urgent (which it is).  So your yell does not trump my squeak… it merely complements.

      And as for the right hook… I’ve never met one where stopping was the wrong thing to do.I agree that my solution does not work in every imaginable scenario; but it is a fairly easy, gadgetless option that works remarkably well.

      • [Funk Daddy]

        Right hooks kill many stationary or barely moving cyclists No squeaks. Better to have properly tuned equipment.

  • [Tadas Jelinek]

    I have squeaky brakes (not on purpose) and live in London. Pedestrians constantly apologize when I stop to give them way even if it’s no danger situation ;) … 

• [Funk Daddy]

  Not bad, almost certain to be abused but the benefit for those that don’t should be had.

  If these were in common use at least we could also see the jerkwads that use it to communicate anything but imminent danger and shun them same as the drivers that use their horn for anything but imminent danger.

  I can think of many real-life incidents and several traffic situations where it could save a cyclists life, particularly right hooks. They may have mentioned that but I watched with the sound off because horn and sleeping family.

  But I seriously doubt the device, as solid as it looks, would remain unmolested in NYC and some other key markets. Needs to come with it’s own tool and matching heads on the bolts, if those are allen bolts the device is gone quick.

• [Funk Daddy]

  Oh and for all the Airzounds fans commenting, yeah, it’s great, but not for every bike/market.

  I’ve designed around an Airzounds on a high end bike, a cover to hide it, because ugly, but customer wanted the function. So he bought it for $20-25 as you mention and then paid me hella more than $95 for his own specific product to hide it.

  Even this one is bulky, but the lack of an air bottle (especially the throwdowns  on zounds) air tubes, the prettier mounting, the low profile actuator, these things more than justify the cost. $95 is very reasonable.

  • [kartwaffles]

     It’s also a complete boat anchor compared to an AirZounds. But for people who value form over function, a couple extra ounces doesn’t matter

• [cservant]

  You know, I can rig you one with a real car horn and a 12V battery pack for about 20 bucks?

  I’ve asked a friend that works in a body shop for a car horn part for halloween years ago.  He gave me a bag full of them.

  The battery could be done with a cluster of common batteries or just buy a specialty battery (like an alarm system battery) for about 10 bucks.

  Tada!  Solder to button, attach parts to bike, and there you go!  Whole system should cost less then 20 bucks.

• [tsoyptc]

  Potential Downside: Scaring the CRAP out of other cyclists and causing them to swerve into traffic.

• [simonster]

  This might seem like a good idea from a safety standpoint, but I can’t help but think it’s going to be used by cyclists to “own” the road, rather than in the rare instances where one needs to alert others of their presence because they can’t stop fast enough to avoid an impending accident.

  In the past, I’ve been nearly run down by cyclists who failed to stop at a red light and didn’t look for pedestrians. Once they have this, I will need earplugs to go to work.

• [Mitch_M]

  My favorite trick in the cab is to beep at a jay walker who is closer to a second car and seeing the jay walker get mad at the other driver for my beeping. I definitely see the potential to use a car horn on a bicycle to play motorists against each other in a similar manner.

• [winkybb]

  This thing is just pointless as a safety device. Car horns have been used so regularly and consistently to convey the message “go fuck yourself” that they scarcely have any other recognised meaning at all. Any use as a warning now comes a distant second.

• [Chuck]

  hmm. somebody using kickstarter to raise money to invent something that already exists. what a shock.

• [Bob MacNeal]

  I want one I can put on a grocery cart.

• [nixiebunny]

  I already have a Loud Bike. It is much more pleasant to listen to than a Loud Bicycle.

  http://www.cathodecorner.com/loudbike/

• [andygates]

  Thinking “awesome, I want one” a decade ago, I got an Air Zound: an air horn for your bike.  Great bit of kit.  But I discovered that I didn’t use it as I expected to: whenever things were *really* hairy, I didn’t have time to parp.  Whenever things annoyed me, I parped.  The horn seemed to turn me into a bit of an asshole, so I got rid of it.

  For most situations, BELLOWING at the people around works as well, tbh.  And it’s faster to deploy.

  • [Lawrence L Lagarde III]

     I love the AirZound. You can adjust the volume so it doesn’t have to be obnoxious. As far as abusing the device, just mellow out.

• [raines]

  Why stop at a horn sound? I had one of these in the 90s, and the siren function was occasionally handy:
  http://www.nytimes.com/1992/01/11/news/a-bike-horn-that-wails-in-the-city-and-chimes-in-the-country.html

  I also have a little handlebar-mounted box that makes a bike bell sound and says “excuse me!” in a pleasant voice. Saves your voice when passing folks in a big group ride or on a trail.

• [Robert Holmén]

   When I was in Paris I was struck by the incessant horn-honking.  It was a continuous drone, day and night, it never, never stopped.  I wonder if anyone was warned about anything by a horn at that point.

  But that was decades ago, perhaps the French driver has become quieter since then.

• [Robert Cruickshank]

  For me, the answer is a Fox-40 whistle. The nice thing is that you can control the volume, for a nice little “I’m here” chirp, or a “closethatcardoorrightf%$#ingNOW” 120dB blast. and your hands can stay on the brakes, where they’re needed. takes a while to get used to riding with it, and you look like “one of those” cyclists, but it’s saved my bacon and that of countless jaywalking peds about a million times.

• [Robo-Design]

  it seems like its too close to the cyclist’s head and would project too much sound right at his ears. Maybe use an extended horn that projects out in front, almost as far as the edge of the front tire, to protect the cyclist’s hearing.

  • [traalfaz]

    I have had several horns on my bike including car horns.  This is not a legitimate issue. I’ve never felt that my hearing was even close to being damaged from a horn, and I have fairly good hearing.  Getting passed by motorcycles with straight pipes, I have honestly thought that there was a chance that I was having permanent damage done to my ears, it actually feels like someone was jabbing nails into my eardrums sometimes.  But not from horns.

• [bolamig]

  I find that a blood curdling “Wooooah” scream motivates people not to open their car doors into my bicycle.  

• [traalfaz]

  I have had a car horn on my bike for about a year now.  Before that I had an AirZound.  The AirZound is actually louder but it’s somewhat fragile and doesn’t work in low temperatures and only seems to work about a year before dying.

  The car horn cost about $45 to build.  All you need is a car horn, a relay and a button from the auto parts store plus a 12V gel cell from eBay.  I guess add another $8 if you don’t already have a battery charger.  I used a shelf bracket to attach my horn to the rear rack.

  Honestly when you are on a bike and get into a situaion where you want a horn, nothing short of the horn from The Mask (the one that shatters windshields and causes property damage) seems adequate.

• [lorq]

  I’d worry that a car driver, hearing the car horn sound, would become confused and instinctively take evasive action in relation to an unseen *car*, which could cause it to collide with the bike.  (E.g. swerving out of a car lane and right into the biking lane, or some similar scenario.)

• [John Wehmeyer]

  Here in NYC, the people with loud horns on their bikes seem to share a personality issue that causes the horns to be used against other cyclists and pedestrians — usually for no good reason at all. So it’s just like having two-wheel taxis behind you. 

• [HammerheadFistpunch]

  My bike’s horn is broken, so I use this. https://www.youtube.com/watch?feature=player_detailpage&v=WqOr60En_kg#t=42s

• [treacle]

  There already IS ONE.  And it’s air-powered, so you can refill it with your bicycle pump.

  http://deltacycle.com/Airzound-Bike-Horn

  They are great.  115db. 

• [a1penguin]

  Guess I was a little ahead of my time.  Back in 1979, I mounted a VW bug horn and a 6V lantern battery to my bicycle.  

  • [Jonathan Lansey]

    indeed you were ahead of your time. Kudos to you though!