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I need your suggestions for my upcoming iBle!!! Answered

I was deciding on whether to let y'all know what I'm working on, and since I don't know much in the area I'm working in, I decided it would be best.

I am working on an amphibious bicycle that can operate efficiently on land and water. There are just a few on the Interweb, and they are for sell at high prices ($500 bucks at least.)

I am trying to do this with as little cost and as much recycled materials as possible.

So far, I've decided that:

My propulsion mechanism either has to be a prop like your average boat, or a paddlewheel. Both would be powered by my back wheel.

I am considering wooden pontoons filled with 2 liter bottles or gallon milk jugs, reminiscent of this iBle.

I want to stay as high as possible, but I want to be able to go straight from land to water and vice versa. Basically, no assembly required to change terrain.

If anybody has any ideas at all, please let me know!

Thanks much,



Couple of suggestions. Get a couple of cheap bathroom scales, set your wheels , one on each, sit on the bike and have some one note the load on each scale so you can properly distribute flotation. I'd build the floats out of "doorskin" plywood, it's 4mm and available at most Home Depots. Fill the floats with expanding foam, and seal with polyester resin (also at HD), be sure to take the density of the foam into account in your flotation calcs. Wear a lifevest, you're one of the non-annoying younger members here, and we need you ;-).

I'd build the floats out of "doorskin" plywood, it's 4mm and available at most Home Depots.

How is the "doorskin" plywood different or better than marine plywood?

Fill the floats with expanding foam

I suspect you mean the type you pour? Would HD sell this in the pour type?

seal with polyester resin

If I knew the cubic ft of my foam, would I be able to figure out how much resin I would need?

Wear a lifevest, you're one of the non-annoying younger members here, and we need you ;-).

Aww, shucks. ;-)

It's cheaper ;-) Marine plywood has two characteristics, it's void free and it can survive x period of time boiling without de-laminating. Since lakes aren't usually boiling my personal test is, if I put a piece of wood in a bucket of water until it sinks, does it delaminate? The doorskins I got at HD did not. (doesn't necessarily mean yours won't) Yes the expanding pourable foam, HD probably not, thou in desperation the cans of "Great Stuff" they sell would work, but West Marine would have it and there are a boat load of stores in Ga. you can't apply the resin to the foam directly it would probably melt it. So let's say you determine you need 5 cubic feet of flotation, build the floats from wood, fill with foam and seal the wood with resin. the bottles of expanding foam will have a chart on the back telling you how much you need to mix per cubic foot, and the polyester resin will have a the same for per square foot coverage (Trebuchet03 has A LOT of experience with resin).

It's cheaper

Good. Any idea on the cost per sq. foot?

West Marine would have it and there are a boat load of stores in Ga.

That there is.

So let's say you determine you need 5 cubic feet of flotation

It's a bit less than 4 cu ft actually, unless I calculated wrong.

Would you happen to know any way I could power a screw prop by my back wheel or from a second chain on my cluster. I have two sprockets from a busted derailleur if that's of any help.

Thanks again!

A 3x7 foot sheet is $8, I know cuz I just bought some for the boat I'm building ;-). A prop? hmmm maybe a right angle drive for an electric drill could be adapted?

Ooo, how about using a right angle drive with a friction wheel turned by your main wheel, and throw in the natural paddle wheel effect.

Eh, you mean a screw and a paddle wheel? I'm sorta lost here....


Reply 10 years ago

From what I've researcher, paddle wheels are very inefficient compared to the screw prop.

Sure they are but his suggestion of using the already rotating rear wheel as a propulsion system isn't bad, though not as easy to implement... So the screw sounded ok to you in the end? Also foam could be a better idea, unbreakable in comparison and the plastic is buoyant in it's own right, adding the air...

The foam is more buoyant: a cu ft of air would support 28.3 lbs, while a cu ft of foam would support 60 lbs.

I will almost definitely be trying the screw first.

I didn't know he meant to add paddles to the rear wheel. I was thinking of doing the same, like this guy.

WHOA! Hold on there, the maximum buoyancy will be from air and approximates 60lbs/cubic foot, all buoyancies go down from there.

Huh? The foam says it supports 60 lbs/cu ft. Did I miscalculate?

Right, a cubic foot of air will support approx 62.5 lbs per cubic foot, subtract 2.5 lbs per cubic foot as the density of the foam and you have 60 lb per a cubic foot. Where did you get that 28.3 lbs per cubic foot for air from.

So using the foam would just help keep water out of the box and make it strong, right?

Where did you get that 28.3 lbs per cubic foot for air from.

Must've made a miscalculation somewhere down the road.


Yes it will make it stronger, and it will keep if from filling with water, It is still important to seal all sides of the wood from water, so coat the inside as well with polyester resin.

If you use the doorskins, you should know two important things, they are very flexible and that can be increased with wetting, so you can make simple curved shapes (I'd suggest a simple 2D pisciform sharp) and secondly the wood STINKS, not just a little, like a three day dead rat but sealing will take care of that.

I worked on my boat today, heres the UPC, might make it easier to find, HD sometimes has this in lumber, sometimes in doors and sometime not at all.

boat etc 053.jpg


I'd suggest a simple 2D pisciform sharp

I've never heard of that. Is like a box that has been "inflated"?

Well "sharp" should be "shape", pisciform means fish shaped. As to the kayak I don't think the shape of the stern will affect stability at all. Stability will come from a wide beam and a relatively flat bottom.


Reply 10 years ago

Also, for someone who happened to be making a small kayak that is all about having maneuverability and stability, would having a flat stern be better than a pointed one?

Woah, you may aswell just copy it... Actually I did have a little idea while cycling up from work, to add the screws in tubes running up the middle of the floats, it seems like over complication in a way but from what I understand it would be more efficient, like using a tubed screw to pump water up a hill... Also you could use the front of the bike like a rudder, since the handlebars turn anyway, a spoke cover for the front wheel could add a little but would be a necessity if the front part of the float was a good shape... From what I see after a second look his boat appear similar in function...

Woah, you may aswell just copy it...

I very nearly am, from float shape to (maybe) propulsion. I don't know what that guy used to fill his floats with though.

I'm still working on the problem of attaching the floats. The guy seemed to attach them to his rear rack and fork via metal rods, but in the video on YT, it shows them able to "fold up", so to speak. Have you any idea about this?


My best guess would be something simple, maybe butt hinges with little lockout latches for each position, wouldn't be too hard to put together, they'd come out on their bars and a simple gate bolt could be used to lock them flat, for up they might just have a hook either side to hold on to...

If you're wanting an easy drive system my best guess would be a wheel either side of the rear wheel at a 90o angle, giving a similar system to a bike dynamo, that would power two screws, though you'd need to use a fixie to get reverse, unless you simply locked out the freewheel on the MTB and put a bolt through the cassette to stop it coming loose in reverse drive...

The thing I really want to know more than anything is how fast you could go and with how much manoeuvrability, it would be kinda cool to have a thing you could saunter about with on the lake and then suddenly tear away when the swans get pissed at you...

Right, I think a prop is a good idea, but technically more complex, since your back wheel will be partially submerged you may as well make it a paddle wheel like that Indian guy.

Gotcha. Have you any idea how to attach the floats to my bike? It seems the other guy used metal rods, but he could still fold the floats towards his bike to conserve space.


Reply 10 years ago

Presumably small hinges where the float attaches to the frame, then a strut between the outside edge of the float and the bike to stop it folding up in the water.

Gah, I keep forgetting stuff! The right angle drive system isn't much more than two bevel gears, right?

How about semi-dismantling a hand drill (or rotary egg whisk), use the tyre to rotate the hand crank wheel and attach your prop to the beater/drill part? Don't know how you'd attach it to the bike, but that depends on how you build the floats ultimately.

Oh, wow, that's cheap! Yay!

I know cuz I just bought some for the boat I'm building

I suppose there will be an iBle on that?

hmmm maybe a right angle drive for an electric drill could be adapted?

I'll look into that. Thanks.

How is the "doorskin" plywood different or better than marine plywood?

It's WAY cheaper. You can get 4mm marine, but prepare for sticker-shock.

It's certainly not as good (more voids, less plys, etc.)....but it's OK. Lots of hobby boats are built with Luaun and other cheapo ply.

Good, good, cheap is good! Thanks!


10 years ago

Does anyone know what I could use to mount the floats to my bike? Thanks y'all!

Sounds like an interesting project. My friends and I drew up plans for our own amphibious bikes back in 7th grade.

If I find our plans, I'll post 'em.

And if you can keep the cost low, I will definitely make one of these.

I'll try to keep the cost low, since that was one of main concerns. How do you define low?

As long as I can find it in the barn (which isn't hard) and then maybe just a few random parts from Home Depot (under $50) then we're good.

Well, most of what I'll probably be using is already listed on this page, so you can go with that unless I find a better/easier/cheaper way.

I would have built one if I still was in MN. Oh well

Are there not any ponds or lakes in your area? =o

Nope. I live in New Mexico (high desert)

Eek. That sucks. I don't know what I'd do without lakes to fish in.

Clarks Hill (Strom Thurmond) is my local lake. Never been to Lanier (yet). Is the fishing good?

(Of course, when I say lakes, I mean mud puddles, since that's really all they are now.)

Dangle your tackle in a gopher hole?

I've never heard it put it that before!

Arrgh, forgot "way".

Ah, well, you understood. =)

Thanks Kiteman! I had seen the Indian man on YT, but hadn't discovered the article! I didn't see that any of them said how the bicycle is steered in water, though. Am I missing it? Thanks again!

He just turns the handle-bars, because the front pontoons are attached to the forks.

Strange how that would turn it though. Maybe I'm just not learned enough. :-)