How to Build a Bicycle Cargo Trailer
If you love using your bicycle to get around, you might also enjoy using it to get your stuff from place to place, too. With a few pieces of lumber and some other easy-to-acquire parts, you can build a simple, inexpensive cargo trailer to attach to your bicycle. On the occasions when you want to carry a heavy load but don't want to start that gas-guzzling mini-van, just hitch up this trailer and pedal away!
1. Decide what type of trailer you want to build. Their advantages and disadvantages are as follows:
Two wheel trailer: greater load capacity, but only stable at fairly low speeds. The connection is also more complicated, as the coupling must allow the bicycle to move both left and right and to tilt. The cost is also higher, due to the trailer requiring two wheels and tires (usually the most expensive parts)
One wheel trailer: greater high speed stability but restrictive load capacity. The connection is easier to make -- the trailer tilts with the bicycle. One wheel trailers are also cheaper to build as you only need one wheel and tire.
Two Wheel Trailer
1. Build the main body. Use 4 pieces of 1 X 2 lumber. Make a ladder type frame by using 90 degree brackets and screw everything in.
2. Find 16" wheels (preferably recycled ones). Attach them to the frame using electric box cover plates bent into shape as shown. You can use bigger wheels if you want to get the trailer even height with the bike so nothing falls off.
3. Attach a trailer arm. Use a malleable metal bar (e.g. from a used, cheap car bicycle rack). Bend and cut the piece into shape. Flatten and drill holes at each end. Bolt the finished arm to the frame tightly.
4. Construct the hitch. Fold an electrical cover plate in half. Make a hole and bolt it onto the wheel and frame of the bike. Then bolt an eye bolt on that bracket. (Put some electrical tape over the eye bolt to soften or remove the clanking noise that is inevitable with this set-up.) Use a U-clamp (also called a shackle) to connect the trailer arm to the eye bolt.
5. Screw a piece of appropriately sized and precut plywood to the top of the frame. Add some eye screws along the edges for bungee cords to hold your cargo in place, if need be.
6. Test drive your trailer carefully. Start with no cargo, then work your way up. Practice turns and acceleration. Inspect all the screws and bolts to make sure they're staying in place. The best way to avoid loose bolts use lock nuts.