River Rider Water Bike




Introduction: River Rider Water Bike

Hi Instructables, here is the abstract for the river bike project I've been working on all winter. This is more of a broad guide on how I made it and what I learned then a how-to make your own river bike step by step.

The best way to figure out the project is to watch the video then skim through extra notes I added here. Don't forget that the youtube player has speed adjustment under the gear icon if you need to see something slower.

Project Goals:

  • Build a bike that I can ride to work on the bike paths then I can ride home down the river.
  • I do not want to have to swim while using the bike.
  • The bike can not sink very far into the water because it needs to float over rocks.

Project Mile Stones:

  • Carve pontoons out of EPS foam.
  • Shape & seal pontoon.
  • Weld legs to bike frame.
  • Constrain pontoons with cables.

Step 1: Pontoons

The pontoons for the bike were the trickiest part, and would have been much easier if I had spent the money on fiberglass. The pontoons are 2 sheets of EPS foam glued & bolted together (glue did not work well). The plywood is there for 2 reasons, first to protect against rocks, and second bolt the EPS together. Notice the bolts going through the pontoons from the plywood to steel straps.

The EPS isn't very water proof, especially when it was 2 sheets, and spray paint will eat it. I should have used Epoxy and fiberglass to cover it. I did use bondo, calking, and wood floor polyurethane because it was cheep. The polyurethane really did a nicer job then I thought it would and after paint, sanding, painting, sanding, then finally spray painting it felt very good. The pontoons feel like the soft foam surfboards from wallmart or somewhere when done.

Step 2: Frame

This is one of my biggest welding projects and my Harbor Freight welder pulled through after replacing some fuses. The basic strategy is to support each pontoon at 2 places and not have the hinges to close to the ground. I used angle iron so it would be stiff in 2 axis's and it was easier to weld to the frame. The easiest method is to weld the bars to the frame then weld the hinges to the bars, otherwise the hinges don't stay straight.

Step 3: Cables

I used cables because it seemed like the lightest quickest way to constrain the pontoons. Basically the bottom cable is doing most of the work by pulling the edges of the pontoons down while the water is pushing them up. The other cables are mostly for keeping everything together when I lean off balance. I'm still playing with the best way to do the cables, right now it seems like the 2 outer cables should be the same length and the bottom cable uses a turnbuckle to tighten everything together.

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    30 Discussions

    Great Design. Loved it. I read below some suggestions for propulsion. Have you seen the battery drill trolling motor? There are cheap on Amazon. A simple battery drill is used for power and A length of metal rod passed through a 1/2 pvc pipe with a propeller attached at the other end. they will move a canoe at a respectable stride.

    Excellent!!! Keep going and post the finished boyke :) Question. What did you use to paint the syrofoam to make it water tight ?

    Come up with something to attach to pedals that would work like a paddle to catch the water. Great idea!


    2 years ago

    Great idea, and if you just modify the rear mudflap, and add a chain set, like those for Snow driving, but with small paddles, you can actually pedal you way!

    Some kind of rudder will be needed, too...

    1 reply

    It's a Tyre chain set, of course.


    2 years ago

    OH..MY...GOD! I am
    not sure what I liked more, the idea or the video! Doesn't matter, I totally enjoyed myself on
    both accounts! The idea was great and
    not over-engineered. Your craftsmanship and ability to incorporate readily
    available materials is MacGyver 2.0!

    Keep up the good work!

    I take it part two of the video isn't completed yet.

    To propel it through the water, why don't you make something that turns the rotational force of the back wheel into a spinning crankshaft to drive propellers?

    Imagine if you were able to squeeze two polyurethane tires, like a pair of inline skate wheels, against the side of the standard bike tire. You would need some sort of clamping mechanism that could be easily released of course to move them away from the back tire when you were on the road, sort of like how bicycle caliper brakes squeeze the back tire. So now imagine a steel rod attached to those two skate tires, and angled down at about 30 degrees into the water. Put a propeller on each steel rod and you have a nice little propeller system with two propellers.

    Next step after that is to put a sliding dropdown rudder on the front wheel to steer.

    1 reply

    Speaking as a complete noob, what if propellors were fitted about where the 'ver' is painted, on both sides of the bike, with a gear system running down to the bottom of the pontoons, so that when they're lowered, the system connects to the sides of the tyre? The props might need protection, like the railings on quadcopters provide.

    I know, this would mean reduced clearance and greater risk of snagging, but for elegant (I think, anyway) propulsion...

    There's another potential benefit. If clearance is going to be reduced at the back anyway, fins, around six inches long, could be put on the front pontoons, at around the same height,so that when lowered, they would provide steering.

    Again, I'm no expert, and there are probably pitfalls I haven't considered, but it's just a thought.

    Cool idea. If you raised the floats up about 6", it would put your wheels into the water which would, A) lower your center of gravity, and B) aid in propulsion and steering.

    Steer by covering the spokes of your front wheel in a solid disc. This would make the front wheel your rudder.

    Help push yourself forward by tying every other diagonal spoke together on the rear wheel. Now when you pedal, the rear wheel would push through the water like a paddle.

    Great instructable! Looked like you had loads of fun making it and just as much fun riding. :)


    2 years ago

    damned crazy thing I'll follow !

    Great concept. I'm looking forward to seeing it complete. For the pontoons, instead of using a cable under the pontoons, have you thought about using a locking support on the top side of the pontoon. Similar to the link below? It may be quicker to deploy and fold back up. http://www.sugatsune.com/180PDF/336.pdf

    3 replies

    Ya that kind of hinge was my first plan but i had a hard time finding somthing cheep that was as strong as in your link. It was also hard finding a place to mount it perlindicular to the botom hinges.

    Bigger folding card tables have something like that to hold the legs out. If you found one that had a ruined top but good legs...

    I see what you're saying. Those things are expensive. Since your hinges are mounted forward and aft of the axle, you could maybe mount a section of pipe (like EMT conduit??) in each pontoon to act as a strut. You could fold down the pontoons, and insert the strut between the axle and a support plate on the pontoon?

    It looks like the cables work, but since you said there's concern of shallow water/floating over rocks, I'd be worried about the cables snagging on something. Regardless of what you do, it's a fantastic project and I look forward to seeing it completed.

    Wow.. this is amazing.. but I think that if the wheels were little bit more into the water it can go faster?


    2 years ago

    You need a 'daggar boards' for the front pontoons - or at least a fin, like you'd find on the back of a surf board. Otherwise your front wheel will drift sideways. Lastly, just like folks put chains on snow tires in the Winter for traction, I'm sure you put something similar on your rear tires that have small fins, like you'd find on riverboat paddles (or paddle boats) Lastly, if you wanted a challenge, rig up a gear wheel that uses the friction of the rear tire to run a propeller on the back. If you did that, you would not need to keep the rear tire in the water. Or you could do both the chain (paddle fins) and propeller. Inflatable innertubes might be another good addition to the outside of the pontoons. And lastly for ocean biking - small outrigger pontoons, like you'd find on one side of Hawaiian 'war canoes'. Good luck with all these ideas.


    2 years ago

    The propulsion system is still a bit sketchy I see :)

    If you weld the hinge a bit higher the wheel will sink a bit more. But I'm not sure if you'll have enough friction to get you move in the river.

    Does it actually work? Does it ride on rivers? Have you tried it?

    Hi, how about buoyancy calculations to make sure your water displacement matches your total target weight and the desired submersion depth?