DIY Flatbed Trailer

Hi all, i've been out of the bike world for a minute so i'm new to the forums, but I've been doing bikes since before forums existed. :wink:

Anyways, out of necessity I recently designed and built a trailer that i just could not find for any reasonable price an equivalent on the market. In building the trailer, i ended up with something that is very simple, sturdy, versatile, and not overthought or over engineered. I basically took a few concepts i saw on various hitch and frame mount designs and connected that to a sturdy, no-nonsense steel flatbed frame capable of taking wheels up to 26" with fat tires. The trailer measures 32"x48" on the outer edge minus the hitch bar with a 22x48" flatbed area where the wood is. By lifting materials up above the wheels though i can get all the width i need.

I built this to haul 8-10' sections of PVC and metal stock home in order to build the two other trailers i need. So far ive' been riding around town for a few days with light loads but this week i plan to try picking up the metal to build the others.

My second one is going to be a bit wider in order to accommodate a freezer, batteries, and solar panel and will be towed behind my reverse cargo trike concession so i can vend ice cream, it'll be self sufficient as long as i park in the sun. My third one i plan to make longer and add an Airstream inspired shell and some popup camper style setup as well as ample solar to allow me to go electric camping without needing to ever plug in. I plan to do some long distance bike travel with a setup like this, like most of the western states.

I haven't painted the hitch bar yet because I wasn't sure if i wanted to mod it. I also may build a few extras and see if i can sell them locally to recover some material costs.

I'm also in the process of designing my own enclosed recumbent bike/trike/quad?(havent decided on the planform yet) to pull the trailers with, something made for range with a low aero shell, pedal assist, and a bit of it's own cargo space.

Thanks for posting this.

Looks a lot like my Mk IV trailer. If you need to lower the bed with larger wheels, you can do what I did there; it's sturdy and has hauled several hundred pounds of large stuff (including wiggly dogs).

https://endless-sphere.com/forums/viewtopic.php?f=2&t=76539




The one thing I've considered changing is the crossbar design; An X-frame instead of ladder frame would not twist as much under varying road conditions and wiggly loads.

I have seen store bought ones discarded in alleyways, or near homeless shelters. Usually they will have a flat tire, or bent rim, might save you some money to find one of those.

amberwolf, that's a cool setup! :lol:

So i think i've decided i'm going to use a trike rear axle and subframe with drum brakes and gears on it and turn it into a low recumbent quad. I've got an old E-trike that has a working drivetrain with sprocket ready to accept any motor. This week i may weld up a minimalist recumbent quad frame prototype with pieces of dumpster bikes and finalize a design for a sleek, aero bubble touring quad and trailer combination covered in solar cells that can expand for camping. I figure with the enclosed shell i can use ram air to push through a set of cooler pads to use evaporative cooling inside and keep things comfortable in the desert. With around 1000 watts worth of solar power i should be able to run all day on pedal assist and save enough power for camping at night. I might start with two 18650 battery banks , 100 or so cells each, with a 12-24v main battery that is part of the solar and another with higher voltage , 36-48v or more to run the drive motor.

That is a cool setup.

Where are you located?
Reason being is that "E-Quads" are not legal in most cases/states. Not trying to be a spoil sport, just trying to save you the trouble if it applies.

Dan

BTW: this is what I was talking about for how I moutned the wheels for a lower deck, but larger (26") wheels:

So the deck actually hangs from the axles instead of resting on them. Mechanically it's effectively the same as far as the wheels/etc are concerned.

It's also easier to repair a tire/tube/wheel issue while the trailer is loaded--the wheels come off by raising the deck off the ground by one inch more than at rest (a jack, stack of rocks, whatever is handy), and then releasing the QR skewer, then pulling down and out and up. I can carry a whole spare wheel for really quick fixes.

Most trailers with double-ended axle wheels require lifting the entire trailer up at least the height of the entire wheel, or tilting it up on one side that far, to get the wheel out. Not easy, maybe not even possible without unloading the trailer, depending on what's on it.

So that's a part of why I did it that way, as well as to lower the deck (for greater stability in turns while loaded, less wind-tippiness, etc.).

Rusty Mustard said:

amberwolf, that's a cool setup! :lol:

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Thanks--the trailer works even better when the trike is pulling it, but I don't have as good a pic of that with a big load, just some with Yogi (~150lbs) in the crate




For size comparison, there's one with the MkIV (still in build phase) mock-attached to the trike (with the trike's rack removed, to use as a flatbed), with the smaller MkIII trailer to the right of it.

So i think i've decided i'm going to use a trike rear axle and subframe with drum brakes and gears on it and turn it into a low recumbent quad.

Click to expand...

Make sure you do a build thread for that--it should be interesting to watch it progress.

But note that as posted by someone else, bicycles (as far as their legal definitions) usually only allow 3 wheels maximum in contact with the ground, depending on your locality. If you're offroad it doesn't usually matter, but for street riding or MUT/bike paths, it could. Mostly I doubt anyone would care anyway, but if someone did decide to pick on you, it might get complicated.

. With around 1000 watts worth of solar power i should be able to run all day on pedal assist and save enough power for camping at night.

Click to expand...

That's a pretty big array--2 or 3 square meters, at least, probably a lot more, depending on the efficiency of the panels and the MPPT or other conversion electronics. (best you can really get with 100% efficiency would be 1kw/sq.meter on the equator at noon....)

As an example, Iv'e seen a panel set at harbor freight (yeah, I know) for 150 watts, which is three panels, each of them something like two feet by four feet...so 7 of those sets in parallel (of three panels) to get about 1000 watts.

I'm sure there are much more efficient ones than the stuff they carry there, but it's still not likely to be a small array.

I'm in AZ but i don't really ride in populated areas and i don't foresee too many people causing problems.

It won't be a small array, it'll be split between trailer and quad, and may end up being that i buy a stack of individual cells and make my own that is integrated into the overall design. I've been on solar at home for the past 5 years or so and i know what i need to do on that end, that's easy.

I saw how you dropped the trailer deck, but i could never do that, i need offroad clearance just to get down the trail to and from my yard.

I think I've got the quad layout all figured out, i just need to get some metal and start building the frame, hopefully this week i can get the main parts of the frame together and order some bb shells, dropouts steerer and headtubes as well as small parts from the framebuilding suppliers. Where should i post a build thread?

I usually see most of the build threads in ebike technical or ebike photos and video.


For the quad parts, you could just use recycled bike parts; just about everything I make is out of stuff like that.


Thankfully the only clearance I have to worry about is driveways and speed bumps.


I'd guess that for the quad thing out in the desert you wouldn't need to worry about it. If you were in Phoenix or another city, someone might care. But at least for now, bicycles are still defined in AZ as three wheels or less in contact with the ground. I don't know if they'll change that with the new ebike laws being worked on (see my thread about that in ebike general).

I'd rather just buy new stuff and start clean for a professional finish, bb shells, headtubes, and steerer tubes are dirt cheap, and i want to order some dropouts, and various brake bosses, tabs, and braze-ons anyways.

The thing i'm trying to figure out now is what size tubing should i figure for. I want to use square/rectangle as i can do more faster with it without power tools, it's easier to clamp stuff to, and personally i like the look of it as well. I like the look of the Atomic Zombie style stuff and how they use it, and looking at the pics of various AZ designs it seems like i'm seeing 1 x 1.5" rectangle and 2" or 2.5" square for the majority of the structure, and various smaller sundry pieces like 3/4 to 1", does this sound about right? I can get those kind of sizes easily at my local shop.

And looking in my pile today, i may use a few of the frames from the graveyard to build a fwd bmx conversion recumbent bike to play with. I probably have enough stuff just sitting here to get one going, The yellow bike in the pics of the trailer is one i got from the dumpster years ago, some ancient univega thing.

I stay as far away from phoenix, tucson, and civilization as possible. riding mostly dirt, and in some stretches the 'cactus slalom' when crossing open desert. After i build a couple of recumbent toys and prototypes to see what i like and get a feel for what i want, i'd like to build one fat tire style with low gearing and some mean suspension that i can ride fast and smooth on washboard and unmaintained fire roads and cattle trails.

I've used plenty of square tubing from 1" to 2" for my trailers and bikes. Except for the few bicycle salvaged bits, the SB Cruiser is built entirely of salvaged square tubing, mostly 1", but with the main "keel" beam/"downtube" of 2". Some of the interconnects, and fender frames, are 1/2".

I abuse the trike with heavy loads, washboard pavement, potholes in the roads, etc., and havent' broken it yet. It's also probably overbuilt, but since my uses are failure-intolerant, especially when carrying the dogs places, I'd rather have it heavy and overbuilt but less failure prone than have it break from a too-weak bit of frame and leave us stuck in the heat trying to jury rig it to get home.


Most of my tubing is weak heavy steel from old retail signage and fixtures, except for the 2" piece which is really stout stuff I got off freecycle a few years back. It'd be lighter and stronger if I had all-new tubing made of good steel--so I expect if you do yours from new stuff you'll be fine--triangulate as much as you can and it'll stiffen it up; you probably know all that stuff already.


In my limited experience, square tubing is actually stronger than round, depending on the application, but it weighs more for that strength.


Typically, I cant' really afford new stuff so I just recycle whatever I can get for free or really cheap. If I could get all new stuff it'd probably make for lighter/stronger trikes/bikes/trailers. But it is also a fun challenge to figure out how to build what I want with stuff not meant for that purpose.

The problem around here is that there's just nothing to salvage. I don't live near the big cities and though i do use what i find, there's just not enough salvage to do anything useful so i just plan to buy what i need new. I plan to 'overbuild' by human standards, i'm a big dude, a bit over 6 and well over 200lbs with massive bone structure, so what i build for myself will definitely have reinforcement and clearance that most would find overkill. I've got size 17 feet and on many commercial bikes and such i run into unexpected clearance issues like kicking the tire when turning, dragging heels on the ground and my favorite, smacking my achilles on the axle bolt. OUCH!

So for my designs i'm going to basically overbuild everything, widen it all so i can fit a 30" or wider seat and like 36-40" wide bars so i don't feel like i'm riding a kids toy, which is what most factory bikes feel like to me. I'll just have to make sure my bb is high enough to not drag heels at bottom stroke.

Whatever i build it won't be light, i could care less about weight anyways since even with the heavy gear i have trouble getting power to the ground. I'm going to use 420 or #40 motorcycle chain for the singlespeed drivetrain and the 10' of it i'll need will weigh as much as a light road bike. I've used 415 hardened chains in the past on bmx and mtb with two stack chainrings and it almost works well enough to allow me to put about half my power into it before bad things happen. I'm also going to use wider sprockets, double stacked chainrings, and possibly even a twin chain setup to reduce the load on a single chain and sprocket. I'll just keep beefing it up until things stop breaking, and since i'll be designing from scratch i can make provisions for stuff like solid CRMO bmx cranks and clearance to fit a 1" wide chain or gates belt if i need it

Hopefully between that and a reinforced seat structure to push against, it'll give me something solid enough to let me spin decent on steep climbs. if i can get 30-40% of my power to hit the ground that'll be acceptable, i'll just have to be careful and walk up steep sections like i do now. Unfortunately though the climb to my place is a 30-40 degree angle ascent over a few hundred vertical feet and every time i've tried to ride it i break something, one time i exploded an ACS freewheel so hard at the 40* switchback that i got shrapnel in my calf and lots of road rash Usually the chain snaps or the chainring goes all taco shaped though, but on a few bikes i've crushed the driveside stay like an empty beer can.

Anybody got any good links to the science of recumbent posture geometry?

Built the lowracer frame today, now that everything is in place i can start fitting a seat drivetrain, and underseat steering setup.

Well my "pickup truck" got it's load on today, i had to get my recumbent e-trike lowracer project, metal stock, tools, parts, and all manner of assorted whatnot down the hill and into town to finish the welding.

https://endless-sphere.com/forums/download/file.php?id=214114


I got all the weight pretty much balanced close to the wheels on the trailer including the forks for piggyback towing and the ride was effortless. Everything just followed along nicely without a problem whatsoever, aside from the strange looks i got rolling through town.

I loaded it all back up again at the end of the day and did the climb back home without much effort as well.

So, as i was wondering how many trailers i COULD pull, the idea came to me that if i can collect enough 'vintage' skinny tire bikes it might be possible to build a pelaton using a tow bike and a pack of 4 to 8 more bikes with foam rider mannequins or something similar by just joining all the cranks and bars side by side. It wouldn't really be useful but it'd be fun to see just what kind of ridiculous thing it would be. I could make the riders pirates or vikings or something silly.

And as for the lowracer trike, it's pretty much finished today as far as fabrication goes, i might have to drill a few more hole, and i still need to clean and dress the welds, but it's ready to bolt together and get laced up with chain.

Well , there's a first time for everything, or so it's said. Well, today it finally happened, while wrestling my loaded trailer down the trail to get home i flipped it over rolled it down off the trail, hehe!

It looks like i screwed up my hitch, the spring i use for a pivot got twisted and it looks like i also bent the crap out of my towbar, and got stabbed with my chainring somehow. At least i didn't lose it down the big wall, it'd be like a 50 foot vertical drop onto rocks.

Oops!

ouch...could be worse--could've dragged you down with it, on the big drop.

Almost did take me down, hehe, i was on the outside and got shinned by the chainring, had to toss the bike over my shoulder to not get taken with it.

I got my other bike built today though, all i really need is a seat, and to install the brakes and some kind of steering apparatus. I'm thinking of going short tiller style with a set of narrow bmx bars i think have enough knee clearance. If that don't work i'll fab up a tiller that will. It's a BMX converted to MBB recumbent. I built a bolt on front triangle and hung the cranks off it. If it's a keeper i'll chuck a motor on it and also try towing with it.

And as for the trailer, i've decided that i'm going to put the batteries, solar panels, and all the power and charging equipment on it, and use a standard plug on all my bikes so i can basically plug in and feed power to any bike. So far what i'm planning is slinging batteries in a box under the deck between the axles, and building a detachable solar panel mount that will be about 12" high from the trailer bed when collapsed but can be raised up as needed with some sort of folding/telescopic arrangement that future me will have to worry about building. Anyways, i've got an air pump and two car battery chargers that i'm going to put on the 12v side of the circuit so i can charge from AC with either a fast charge or a 1a slow charge. I'll set up a pigtail so i can plug in to RV power as well as tossing an inverter in the system.

I also want to come up- with a way to get it off the wheels and leveled when parked, so i might try some corner legs with feet that either pivot or slide down and take load off the wheels. I'll need this kind of setup for my camping trailer so i may as well start figuring out the best way to make it happen without hauling around a bunch of jackstands.

Old crutches or walkers, they have the push-in buttons and row of holes to adjust height. Li-ghtcycle used this method as a stand on his cargo pods added to his bike, a few years back. I was going to do it for my pods on CrazyBike2 but then I built the SB Cruiser trike and didn't need to.

The problem with crutches is that they're aluminium, not strong enough. I'll make something out of square tubing, i'd destroy crutch legs. I've got a rule, no aluminium as far as tubing is concerned, or at least not for anything structural. Billet parts like stems, hubs, and such are fine, but anywhere else would be a waste of time and metal.

Then maybe the bedside potty seats--those are steel, and quite strong (my Crazybike2's seat is built out of the frame from one), and have the same type of adjustable legs.

If you were down this way, I have a bunch of strong steel square tubing adjustable pieces, each about a foot long, so about two feet when fully extended. (meant to hold heavier retail signage cantilevered out from the aisles). I'm using four of them to hold up the SB Cruiser's canopy and rear rack (though I'm using bolts thru the adjustment holes rather than the little push thingies due to the weights of cargoes I carry, since mine don't just hold the weight while still, they have to take the pounding of a ride):