Extremely Loud Train Horn Bicycle




About: A newbie DIY enthusiast in the process of becoming a pro.

So you want to be loud? You want to make a statement? You want to scare the crap out people? A train horn will do the trick. Do you want to stand out in the process? Than a bike with a train horn attached will defiantly do the trick! 

So you may be asking yourself why would you possibly attach a train horn to a bike? Well the first reason is that I currently do not own an automobile, so this is the best that I can do. The second reason is that it just so unexpected and fun to use. Have you ever heard a train horn in the middle of the street and seen that it was coming from a bike? I didn't think so.

To start off, let me explain some things:
     1. The reason why there is a portable air tank on the back of my bike is that hooking up an air horn to an air tank is much louder than attaching an air horn with the provided compressor. 
     2. The horn I used can be heard from over half a mile away. Although this is not as loud as an actual train horn, it does the job.
     3. The total cost of the project varies. If you happen to already own all of the materials, it will cost nothing. If you own none of the   materials, it could cost over $200 to construct.
     4. It takes about 30 minutes to construct.
     5. This is an extremely fun way to scare/prank innocent pedestrians, although it should be used respectively. Blowing it near traffic is NOT a good idea!

Step 1: The Bike

The most important part of this instructable is of course the bike that your going to be using. While you could use any bike for this project, a cruser is 100% recommended. The reason why I recommend a cruser is that most of them include luggage racks on the back. This luggage rack is vital because this is where you will place your air tank.

* If you do not have a bike with a luggage rack, you could build one using either wood, metal scraps, or even PVC pipes. 
Some nice instructables on building bike luggage racks...
                carpespasm's instructable
                darlingtom's instructable
                graphicsman's instructable

Step 2: Materials Used

Materials Used:
    - A 10-gallon air tank. (Any tank will work)
    - Dual trumpet air horn. (Any large horn will work)
    - 2 bungee cords (Any strap will do)
    - Duct tape
    - Air blow gun attachment for air tank
    - 4 foot long 1/2 inch thick hose (running from the air tank to the horn. Any length of hose will do)

Optional Materials:
    - An old towel (so the air tank doesn't scratch the bike luggage rack)
    - A large hose clamp (for placement of the horn)

    Air Horn-   Any where from $15 to $200 on Amazon. The one i used is HERE
    Air Tank- Any where from $30 to $60. I used some old tank. You can buy them HERE
   Bungee Cords/ Straps- Very cheap @ any local hardware store. About $5 each.
   Air gun attachment, duct tape, hose, and large hose clamp- Very cheap @ any hardware store.

Step 3: Attaching Materials to the Bike

Now that you have your bike ready and your materials on hand, it is time to construct it all. 

             Before Attaching the Materials:
1. Fill up the air tank with air. Over half a tank is recommended.
2. Make sure that your portable air tank is attached to a piece of 1/2 inch thick hose. The length of the hose is up to you.

             Steps To Attaching The Materials:
1. If you don't want to scratch your luggage rack on your bike, place a towel down.
2. Set your air tank on top of the luggage rack.
3. Take your bungee cord or strap and wrap it around the air tank and the frame of the bike. (Be sure to wrap it around a secure spot on your bike frame)!
4. Take your other bungee cord or strap and wrap it around a different spot on the bike frame and the air tank. (Attaching any other cords/straps for extra support is recommended but optional).
5. Take your hose running from the air tank and strap it on the frame of the bike using (duct tape) until it reaches the handlebars on the bike. 
6. Try to place the blow gun attachment at a comfortable position on the handlebar. Strap it down with duct tape. 
7. Attach the blow gun attachment at the end of the hose to the hose from the air horn.
8. Position the horn on the handlebar. This is where the hose clamp may come in handy. Luckily this bike has a cup holder to position the horn on so a hose clamp is unnecessary. 

Step 4: Test Drive

You are finished! Now that wasn't so hard, was it? To blow the horn, simply make sure that the air tank valve is open and push down the lever on the blow gun attachment.

Now that your amazing project is completed, it is recommended for pranks, scares, showing off, and just having fun. The possibilities are all up to you! 

Please comment and favorite if you like it! This is my first instructable so please follow me for cool new ideas. Oh and one last note, if you see the police, i DON'T recommended blowing the horn. 

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    41 Discussions


    2 years ago

    awesome! I have Ontario northland train horns, so I will mount them on my pickup truck, instead of the bike. All mount them in the truckbed so no one will think that I have train horns in my truck bed. All also use a bigger compreser.


    6 years ago on Step 4

    that is utterly ridiculous and want it on my bike


    7 years ago on Step 2

    If the bike is tipped over or crashed and the tank gets cracked or the valve breaks off, what are some of the safety concerns for having a air tank strapped so close to a person. Don't want a Wild E Coyote incident happening with the tank. I have hear of large high pressure tanks falling over and the valve breaking and the tank getting shot through cinder block wall and wrecking cars in the parking lot. Old retired dude told me that story.


    7 years ago on Step 3

    Cool project!

    But I'm afraid I'm gonna have to jump on the safety bandwagon here, but I'll jump off pretty quick.

    You say the tank is old. When compressed air is cooled, the humidity in the air condenses and pools up in the bottom of the tank. The tank is probably fairly rusty on the inside, especially where it's welded together. Assuming the tank is about 8" diameter, you have roughly 50 square inches in the welded-on ends of the tank. Assuming a modest 100 PSI (you didn't say what pressure you fill it to, or I missed that part), that's 5000 pounds pressing against it. IF the weld were to break simultaneously all the way around, and someone got in the way, they would be hurt, probably severely. It's unlikely, but I like to play it safe... when there is no fun lost in doing so :)

    I DON'T suggest doing the following (it's probably considered dangerous or something..., I want no liability here):
    What I do to pressure test an old tank is duct tape the pressure relief valve so it doesn't open at the pressure it should. Somewhere on the tank it will have a maximum pressure and burst pressure stamped into the metal. I fill the tank to 20-30 PSI below the burst pressure (or as high as my air compressor goes, depending what the rating is) AFTER placing it in a steel box. I fill it while monitoring a second pressure gauge outside the steel box. If it holds up, I use the tank for another year. I had one break once, and it put a good sized dent in the side of the 1/8" thick stainless steel tool box in the bed of my truck. But it was also about 14" in diameter and burst somewhere around 140 PSI, so a lot more force.

    1 reply

    Reply 7 years ago on Introduction

    Hmm good observation, however I would have to say that there's a much better chance of falling off your bike and getting seriously injured, then the tank exploding and seriously injuring you.


    7 years ago on Introduction

    While this is a really neat idea in theory, I have to add another caveat to this. If you are anywhere near traffic, don't use it. I don't think the owners of these things realize how startling they are to the unsuspecting motorist/pedestrian. I have a neighbor who has one on his truck, and I've seen dogs and cats dart into the street, cars hit the curb and go into a lawn, and several almost-collisions when he's blown his horn. People will most certainly slam on their brakes, swerve (hopefully not into your bike), and do all other sorts of unexpected things when you blow this horn.

    If you do decide to use it, I hope you have good insurance.

    3 replies

    Reply 7 years ago on Introduction

    Having been personally run off the road, and chased by countless dogs, I would not hesitate to use this, I will be the first to buy one when they are miniaturized and I will laugh when the guy that was about to kill me "is startled". I love this thing.


    Reply 7 years ago on Introduction

    Not as loud, but you can buy a miniaturized one:


    7 years ago on Introduction

    I was thinking about this, strapping the air can to the bottom of a trailer and out of the way. I think Micah hit the nail on the head below though. I've got a Hill pump that can do 3300 PSI. So fill a reservoir with high pressure bottle with high pressure air attach a regulator and you're off with an air can that can fit in a water bottle holder.

    DIY Micah

    7 years ago on Introduction

    Another idea might be to use a paintball air tank. You can find them pretty cheap and I think they'd hold enough air for a couple blasts. They'd also be smaller and lighter and less conspicuous. Plus, people like GRBTA could probably equip a motorcycle with one a litter easier than a massive air tank; a paintball air tank could easily fit inside a saddle bag or in a backpack.

    1 reply
    SkymeatDIY Micah

    Reply 7 years ago on Introduction

    That's an excellent reply. A regulator could take the pressure to whatever you want. Easily refillable too. Though I'd think a non-cryogenic gas would be in order due to the amount of air required. So no co2, but nitrogen or scuba air....


    Yes, its frustrating on a bicycle or Motorbike when you are not noticed and put in danger by other road users, but a louder horn (from 20+ years riding experience) does not make you safer in 99% of incidents.

    Its great if a pedestrian waddles out in front of you, a loud horn will give them an obvious warning, but for actual danger situations - basically if a car has swerved across you and is heading for impact... blowing your horn will just reduce your controlled braking reaction time. Sure, if a car is slowly drifting across a lane it will help - but that is not a terminal manouvre. Regardless of that, i would always install a set of compact air horns on my motorbikes, however i never felt that much safer with them on board, its road craft that will keep you alive - not relying on a loud horn.

    On a bicycle its not much different, except you are going to be peddling this extra weight everywhere with you, and when you need to leave your bike somewhere - is this going to be tempting for somebody to steel? or maybe you could carry your huge air tank in a bag with you for safety!

    So i would also lean towards airhorns on a detachable bracket for a bike. I built some spotlights for my bicycle that are powered by an SLA battery in a drink bottle, the bulk of the setup dettaches in seconds. It would be possible to do something similar with a minicompressor and avoid carrying the huge air tank.

    The risks and inconvenience seem to outweigh the benefits, regardless of that i commend the builder on their ingenuity, it is an innovative build - and an interesting read.


    7 years ago on Step 2

    The first link is broke. Try this

    1 reply

    7 years ago on Introduction

    I have hooked up 'Semi-tractor' style air-horns on several vehicles (typically mini-pickups). Love to see how quick 'oblivious' people come to life when they hear that Howl. I do have a couple of train whistles, but never considered hooking them up on a vehicle. I do believe they would have even more 'Wake-up' effect then the air horns. BTW - - Nice instructable - -

    Be careful - some cities have completely outlawed train horns on ANY moving vehicle, and yes, bikes count!

    Still, this is a very cool idea, and could be a good thing for bike safety in a slightly quieter version.

    Might also want to beware of using this in residential areas.
    I'm a third shifter and asleep in the daytime.
    If one of the neighborhood kids used one of these in the middle of the afternoon, I would call the police on the little brat after I unstuck myself from the ceiling. And since I'd be unlikely to be able to go to sleep again, it would cost me a days work. Can't afford to use high speed power tools like I do when too tired, so I would be looking for a way to scare the piss out of the kid that did it.


    7 years ago on Introduction

    Did a thing like that on a motorcycle: Pull up some speed, Pull the clutch, roll out & USE THE AIRHORN !!"!


    7 years ago on Introduction

    Visiting a small town near Colon, Panama in 2002, I was deeply startled to hear a giant truck horn only to turn around and see a grinning 10-year old on a bicycle. They connected truck horns (same thing it seems) to rechargable fire extinguisher bottles, often with a dedicated bike pump attached for "refilling" the tank.

    Very fun, very cool.