Q&A for How to Build a Bicycle Cargo Trailer

The wheels are attached to those metal plates by sticking the axle through a hole in the plate (which you have to drill). They are then secured with the nuts that come with the wheel. Then the plates are screwed or bolted onto the wooden frame. Because of the confined space where the wheel sits, this may being really awkward. So my plan is to cut a slot in the plates so the axle can slide in/out (on a bike, these are called "dropouts"). I also plan to use quick-release "skewers", since I also foresee having to load this trailer into the car, and I'd prefer to be able to remove the trailer wheels easily.

The ladder is the frame of the cargo trailer. Attach plywood to the ladder after the wheels are attached to the ladder.

There should be a screws with the trailer. Weld the hitch with a nut fit for the remaining part of the screw and attach the nut to the remaining part of the screw.

Follow steps 3 and 4 above, or go on Craigslist and find a cheap used bike trailer for pulling kids. It will have most of the parts you need, minus the frame and bed.

You'll need to make the arm from recycled metal tubing from other trailer hitches, foldable furniture, or sturdy baby-stroller frames. You could also bend one from electrical metallic tubing (EMT). You need to create the space for the wheel to swing through when you make a turn. At the hitch-end, bend the bar outward at an angle that allows the tire to turn through. Making a stick-figure of this, top-view, where the first line is the bike tire, and the second is the arm. Do it like this: |\, not like this: ||.

With a single-wheel trailer, the single wheel is at the back and the cargo platform sits between the trailer-wheel and the back bike tire. The cargo platform is much smaller. Imagine a wheelbarrow being pulled backward.

The design is completely different and needs a separate post and illustrations. Essentially, you set the cargo platform (much smaller) between the trailer wheel and the back bike tire, and the wheel is centered in the frame. Imagine pulling a wheelbarrow backward; that's how a single-wheel trailer operates.

It depends on what the dimensions are, but if it will fit, then you just need to have sturdy contact points for mounting.

It is possible, but it would be best to use strong wood like an ash tree or hickory. A metal arm will be cheaper.

16 inch wheels are common as size for children's bicycles, but you can also choose 18 or 20 inch wheels. Consider adapting the basic frame depending on the chosen wheel size.

Though you can make your trailer as wide and as long as you wish, the recommended width is about one of your shoulders. The length is determined by your application. Most mass-produced heavy duty trailers with a rated capacity of 150 kgs do not exceed 150 cm length.