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.