The Hermit Crab
-NOMADIC LIVING IDEAS TO KEEP IT SIMPLE-
After scratching my head for ages as to how I would make the lightest structure possible that would well support my weight, I found out that professionals were already making and selling exactly what I needed. The main frame I used was one that comes from the company called Bikes at Work. They sell bicycle trailers that are made to support 140kg (300 lbs) and happen to be the exact width to sleep in comfortably and store some stuff around you. The trailer I bought from them was the 96AW. It takes a big worry off to know that the supporting structure won't fail on you in the middle of the desert!
Here it is: http://bikesatwork.com/store/product/96aw-bicycle-trailer
There are two things I changed to the supporting structure. This trailer is perfect as it is for the road, but I wanted to make it off-road compatible so I would have the option to pull it by hand across fields or in the forest. For that reason I replaced the wheels and their axle by standard 24 inch bicycle wheels on two stainless steel axles. It was a lot of work and required to drill through stainless steel, so if you don't intend to use it off road, it's not necessary. Also, Bikes at Work would agree to sell slightly bigger wheels that work on the same axles, you just have to ask. They're great guys, by the way.
The second thing I changed was the length. I simply cut one of the sections by hand with the hacksaw (only took a few minutes) to make the total length 2 meters (79 inches) instead of 2.4 meters (96 inches).
The trailer after having reduced the length, but still with the original 16-inch wheels. You can see there is space on the sides beyond the thick rectangle frame and above the wheels: that will be our storage space.
Making the usable space as wide as the wheel axle
This is about optimizing space: making as much usable space without making the vehicle any wider. This means using the space over and around the wheels, instead of letting the wheels stick out as they do in the original trailer. You can see on the photo that there is a metal sheet about 10cm (4 inches) wide extending on both sides and going over the wheels. This is a 1mm thick aluminum sheet, easy to cut with a jigsaw, and easy to bend. To support it, I replaced some of the 82cm (32 inch) bars going across by 1-meter bars. This added the 10cm (4 inch) surplus on each side onto which I drilled-and-bolted the aluminum sheet. It makes great extra storage space on the sides without making the trailer any wider.
The new standard 24 inch bicycle wheels I mounted. Notice the shiny bar closest to us, and the shiny bar on the other side of the wheels: these are the stainless steel axles. Standard bicycle wheels need to be attached on both sides of the axle (unlike the Bikes at Work wheels, which are only attached from one side), so I couldn't just make a simple axle in the middle.
I had to make two axles (photo: the two shiny bars on left and right), which connected to two more stainless steel bars (photo: the shiney square bar closest to us), making a square frame that goes around both wheels, supporting the outsides. It's the only part I made of stainless steel, because it's supporting all the weight.
Drilling through Stainless Steel
This square frame supporting the outside of the wheels is also drilled-and-bolted, so it required me to drill stainless steel. It's not hard as long as you follow a few tips. First of all, cobalt drills work best and last a long time. In the hardware store, ask for cobalt drills made for stainless steel. They're more expensive, so buy only the diameter corresponding to the bolts you'll use. Second, mark the place you will drill with a center punch and hammer. This will prevent the drill bit from sliding all around. Making a pilot hole can help as well (a much smaller hole with a smaller drill bit to "pilot" the bigger one), but it's not necessarily necessary. Finally, use the cobalt drill with quite a lot of pressure, at low speed, otherwise the stainless steel can "work harden": become harder and harder and all purple, until it is almost impossible to drill through.
Making the Wheel Attachments
Hitching the wheels to this structure wasn't complicated. All I did was buy a one meter long (3.3 feet) thick aluminum angle bar, cut it into 4 even parts (you can see all four on both of these pictures), drilled a hole through the very middle big enough for the wheel axle to go through, cut through to these holes with the hacksaw (making the upside down U-shape), and attached these 4 pieces to the frame with bolt and nut. You can see almost every part of this process in these two pictures. As you can see, I also bolt the two inside pieces to two thinner aluminum angle bars, connecting them together and supporting the floor.
The Floor
You can do this relatively late in the process, I almost did it at the end. The Bikes at Work trailer is made to accept a 6mm thick (1/4 inch) plywood panels 60.5cm wide (25.5 inches). Loosen the bolts, slide the panel in there, and tighten the bolts again. Before putting any plywood though, make sure you weatherproof the outside with any kind of wood sealant (instructions below).
Weatherproofing the Wood
You're going to do this for any wooden surface turned towards the outside. You should only weatherproof one side of the wood panel, because sealing both sides can trap air bubbles between both layers of weatherproofing that may make it crack when the sun heats it up. However, the inside can be treated with linseed oil (or any other water-repellent oil) to make it resist water a little better without making it airtight. Here's how to weathproof the outside.
Start by briefly sanding the wood with relatively fine sandpaper. Don't worry about details. Apply a layer of wood sealant (any kind you find in the store will do, don't waste your money), and let it dry for 24 hours. Now do these three steps two more times, so that you have a total of three layers of wood sealant. Now you're protected!
Brakes
These brakes are useless if you're only intending to pull it by bike, but hand-pulled, brakes can be a lifesaver in a downhill. They saved mine.
The brakes were easier to mount than I expected. I bought the simplest caliper brakes for around 6$ each. These brakes only need to be attached at one point (the middle axis you can see on the picture), so I drilled through the front stainless steel axle (with a cobalt drill bit) and just mounted them there. Very easy. The brake cable then connects to the handles at the front, we'll get to that later.
A caliper brake