The Amphibious Bicycle




    In this design, I tried to make a bicycle that would be able to move in both water and on land. Even though other similar designs are out there, the eloquence of this design is that there are no adjustments needed to switch from land to water. One simply rides the bike on land, down an incline into water, and continues to ride in the water.

    For buoyancy, I decided to use a lot 1 gallon milk jugs to keep the cost down. According to Archimedes' Principle, the weight of the amount of liquid an object displaces is equal to its buoyancy. Because I weigh about 175 lbs and I estimated the bike to be between 35 and 45 lbs, I will need a total of 250 lbs of buoyancy. This is 32 gallon jigs.

    In order to get all of the materials I needed, I kept it cheap. The bike I got from a friend, but there are always cheap bikes available at garage sales. I used old tent poles as support. Duct tape and twine are relatively inexpensive. My biggest purchase was the wood that I needed, which came out to only $20. The largest purchase I made (well it was free so it wasn't a purchase) was getting all of the bottles from the recycling center. Get ready to go dumpster diving!

    Riding the bike on land is no problem if you put the floaters far enough in front and behind the pedals. Then, it is just a matter of getting used to the additional structures on the bike. Mine, for example, is not able to turn and pedal at the same time because of the floaters. Using twine or something simple will be enough to keep the floaters from hitting the ground.

    One of the most complicated parts of the build was keeping the floaters down while in the water. Because about 250 lbs of force will be pushing up I needed very strong supports. Unfortunately I only had tent poles, which were strong enough to keep only the bike buoyant. If I reinforced these with additional poles, the bike would be able to support myself also.

     The directional system in water is just the same as it is on land: turning the handlebars. Once moving by pedaling, that will allow the bike to turn while in the water. Because of the enormous amount of upward force present in the water, I was not able to test the bike with myself on it. However, if you wanted to adding a rudder wouldn't be a big problem.

    The propulsion system is lacking, but while pedaling the rear wheel will allow for some forward momentum. I had an idea of attaching a wheel to the rear wheel and water wheels to that, so that when you pedal the water wheels will propel you forward, but only in the water. However, you would need two wheels attached the the rear one if you want to go forward when you pedal forward!

    As a prototype, this design worked very well. With only a few minor adjustments, this will be able to support a person on the water and be able to go forward, however slowly. Feel free to duplicate this but be sure to let me know and post pictures so that everyone can see!

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    13 Discussions


    Does it go fast in water or do you pedal real fast but it barely goes. I was just thinking the verticalness of the walls wouldnt be able to get much traction. Maybe some packing tape from one side of the wheels spokes to the other side? Omly problem then is there'd be more air drag for land travel, though I dont think much more than the milk jugs already create. I opened this instructing thing this is hilarious I have to see this but it actually is pretty awesome. Learned something cool, thanks! I dont think there would be4 problems with the rusting. I mean your in the water then you're out and it dries. Chain would be more likely to rust from leaving bike out the rain, that exposure over time.

    3 replies

    Actually, it never stayed upright with me on it because the force of the weight of the box was too much for the containers, and in particular, the connections. (Most were tape/ string/ tent poles/ etc.) To be practical, I would imagine all of those would have to be welded togethor. Widening the clearance of the rear wheel and the seatstays may or may not be necessary to create a propulsion system based off of wide and flat rear spokes- similar to a paddle boat.

    What do you mean-are you saying the bike never stayed upright in water? Here's a couple things that might be interesting to you. The first one is a link to the 'aquaskipper' instructable. I;m thinking bike plus that...? The next thing is a picture of a bike antitheft shell cover. If it were clear it would work as a bike roof and I would imagine you could add aquaskipper fins to it. I realize that both suggestion are pretty lofty builds. Hopefully you'll get the thing working with better connections:) 2 3 foot sections of large diameter pvc pipe with endcaps may be a lot easier to balance than a lot of milk jugs, though more expensive and less hilarious than the milk jugs.

    bike roof.jpg

    Thanks for your suggestions. What I meant to say is that had I been on the bike when it was in the water, the whole thing would have fallen apart because the connectons weren't strong enough to suport the weight.


    Reply 5 years ago on Introduction

    if you know metric, 1 ML of water = 1gram

    so TECHNICALLY 13.78003318 gallons is enough to support you

    add another 35 pound for the bike, and you need 17.97397585 gallons

    but you want to float above the water, not be at in the water.. so yeah 25ish gallons is fiine.



    8 years ago on Introduction

    wait so can u actually move it in the water?

    Inventive design!

    dude, your chain is going to be totalled. you should also hink about how high your feet need to be out of the water...
    keep me posted; i am really looking forward to the end result!