Tuesday, July 11, 2006


How would I build a very large flatbed bamboo cart that could be hitched to 2-3 bikes. I imagine that this vehicle would serve as the base for a human-powered "artcar", to be taken to Burning Man, ( www.burningman.com) and would ideally be able to support up 6-12 people sitting on the structure, along with a cooler, and small music system.

What we describe is how to built a flat eight foot square platform trailer supported by castor wheels, and towed by three bikes on rope. Any superstructure can then be built onto the flat platform. Everything will unbolt easily for moving it. If anyone is daft enough to build what we are just about to suggest we take absolutly no responsibility for the shape they may end up.

1) Build the platform
Imagine this as an oversized wooden pallet, the build style is exactly the same just bigger.
Make the stage floor from two 8'X4' sheet plywood, say 3/4" thick layed side by side to create an 8'X8' stage. Lay these sheets on the ground with the long axis so it runs front to back. Lay three 8' long 4"X3" beams widthwise, one at the front one at the back and one at the center(the beam depth is 4", width 3"). Now lay three 8'long 4"X1" planks ontop the 4X3 beams, this time running front to back, one left one right, one center. This creates a stage with basicly the same structure as a large wooden shipping pallet. Tack this layout together with nails, in such a way that the nails can be removed later. Everything will be held together by the bolts that hold the wheels on.

2) Attaching wheels
You will need nine 250-350mm Diameter phneumatic castor wheels six must swivel, three must be fixed, they should be the type that can be bolted with four bolts to a flat surface. These can be bought from companies like Northern tools at a reasonable price.

The left right beams and the front back beams cross in nine places. At each of these crossings bolt a castor wheel. The three castors that run accross the rear should be fixed to face forwards the other six should be able to swivel. This allows the trailer to turn, but not slew.

Make sure when placing the wheels that at least two of the bolt holes will pass through the left right beam, front back beam and plywood floor. Use offcuts to make sure no bolt goes trhough thin air. Drill all holes and number/mark all pieces so you know where they go. Then bolt the whole rig together through all these holes.

3) Brake
You will need to slow this thing down, the brake we suggest is more of a parking brake, and is not intended to be used at speeds over 10mph.

Hang an 8ft width wooden beam just ahead of the rear three wheels, this should be suspened by two pieces of rope at its left and right extremity. These ropes should be long enough to let the beam rest on the ground. If the beam rests on the ground when the trailer is moving the beam is dragged back and jams between the rear wheels and the ground. Rope length is critical, too short and the brake will not jam the wheels properly, too long and the wheels may ride over the beam and make it useless. Next tie a rope to the center of the beam, this will be the control rope. Drill holes through the top middle of the middle and front beam, and pass the control rope through this. When the rope is pulled tight by someone at the front the beam swings of the ground and away from the rear wheels, when released the beam hits the ground and slows the rear wheels.

This is not a sensitive way to control trailer speed, you have been warned.

4) Hitching to bikes
Hitching to multiple bikes is easy. They could either tow single file or three abreast. Assuming decent ground and walking pace a assume about 200kg/bike. You can use rope to connect bike(seatpost) to trailer, and bike(headset) to bike(seatpost). Remember though with rope there must be someone on the rig to brake it, as the bikes can't.

Three bikes abreast would probably do, two tied to the outside corners of the front and the thrid in the middle. Experiment with rope lengths to get the best distance between bike and trailer. This thing needs teamwork to ride it. Best to have a brakeman on the trailer who is not cycling, and three cyclists. One needs to be captain.

Thats pretty much it, you can slap on any top you want, even put a skirt around the wheels to make the trailer look as if its floating. What weve suggested may not be the best way of doing things. Imagination and inteligence should overcome most problems.


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