Wednesday, January 31, 2024

The Rational for a Bicycle Caravan Build

I would need a trailer to have enough surface area for sufficient solar panels. I thought of mounting a tool box on a trailer and then attaching a solar panel on the lid.

Problem. The size of solar panels. 100 watt solar panels are about 1 metre long. To get higher output, the size increases to about 1.5 to 1.6 metres. I wanted more than 100 watts. My tent is 1.9 metres long. If I was going to have the length about 1.5m, I might as well go longer so I could sleep on it.

I like sleeping in my tent, but finding a test site is hard. It has to be reasonably flat, no rocks, roots, prickles, grass clumps, dips, water, etc. A trailer has its downsides on the size of it, but it would be an advantage to sleep on top of it and be above all the ground problems.

I spent weeks looking at different designs from western wagons, fold out and pop top trailers, and caravans. Drawing up paper plans and examining how to build them, and the weight, and how they would work day to day. The size to tow behind a bicycle and sleep in or on it added to the challenge. Every decision has consequences and trade offs. Size, weight and cost.

The solar panel on the roof, so I'd have to sleep under it, or have it moved out of the way to sleep where it was mounted. I did consider sleeping on top of it, but couldn't get a working idea. If to move it out of the way, how and where to put it.

Ideally, I'd sleep low down, not very high off the ground for stability. One set of wheels near the middle with a metre on either side doesn't allow a lot of ground clearance going up inclines. I'm using 20" wheels. Can add more wheels, but that increases the weight. Removable wheels and having the trailer sit on the ground is possible, but I decided against that. Without single sided axle wheels, it would be inconvenient to remove and replace the wheels daily. To sleep low, it is between the wheels on the floor. Wheels axles need support. Wheel is 100mm wide at the hub, 25mm for the supports. That is 300mm of the width just for the wheel spacing. Wheelchair wheel hubs are only supported on one side, but this only saves 50mm for significantly increased wheel costs. Ultralight sleeping mats are 520mm wide, but more comfortable is 600mm. Already the trailer is 900mm wide. I'd like the trailer to be thinner, but 600mm for the bed needs a bit extra for movement, say 100mm each side, 800mm is the lowest width that I was happy with. The width of my tent interior. This is without considering the wall thickness or...

The height. Too tall and skinny and the trailer will tip easily. I liked the western wagon design as it allowed the canvas to be raised letting the wind blow through.

A width of 800mm has the wheelbase in contact with the ground at 700mm. 20" wheel axles are 260mm of the ground. The floor would be above that. To sit up in bed needs a minimum of 950mm height. This totals 1210, but ignores the floor, bed and roof thickness. The axle mounts add a bit of height as well. Don't stretch up or move upwards without ducking the head.

I really liked the western wagon design, but settled on a more conventional caravan look. Flat roof for the solar panel. The walls would be 30mm thick laminated foam panels. Plugging this into the constraints, the caravan ends up:

Width: 960mm
Height: 1500mm
Length: 2200mm (Not including the drawbar and hitch)

Width: 900mm
Height: 1200mm
Length: 2160mm

The ground height ends up at 300mm to the top of the floor inside, and 1500mm to the top of the roof.

Western wagon example But my design had two wheels only. No sheep.

Folding bicycle caravans A lot of different folding and opening options.

Peter Petersen The one that I settled on for inspiration.