Introduction: Single Wheeled Bike Trailer
I wanted to recycle an old foldaway bike I used for an earlier recumbent project to make a one wheeled trailer. I was inspired by an earlier instructable but didn't want to do any welding, just nuts and bolts. I'm a big fan of 1/2" conduit for lots of metal projects. This project took about 2 weeks off and on. I'm going to use it when I bike around town or to the beach for the day and carry lunch, drinks, boom box, etc. It's not meant for heavy loads. That's another project for another time.
Step 1: Modifying the Frame
Here's a shot of the under side. I cut the existing frame and modified the vertical angle of the handlebar collar to be perpendicular with the ground so it wouldn't jam up when it pivoted. Geometry is critical here.I had to used plate steel and bolts to join the frame because of no welder. I reinforced the 1/2" plywood top with sections of 1/2" conduit that where flattened and bent in my bench vise. They were secured to the frame with sheet metal screws and eye bolts. I used cap nuts to finish the connections off to look right.
Step 2: Hitch Mechanism
Now for the hitch. I picked up some ideas from other trailer designs I found on the web and hoped my conduit would hold up. It seems to work fine. Here's the details: I used a 3/4" piece of steel plumbing pipe and 2 caps to join everything together. It was great, no excess wobble in the collar or up and down motion. Whisper quiet. The hitch resembles a triangle shape which is very ridged. 1/4" bolts everywhere. The sectioned where cut, flattened and bent in my bench vise. The edges were ground to look nice. I had to estimate the space needed for the tire and distance to the trailer.
Step 3: Attaching to Bike
I made a flat steel bracket to bolt to frame and allow hitch to pivot up and down. It's mounted behind bike rack bolts. I wanted the hitch to be independent of any rack mounting.
Step 4: Safety Light and Battery
I didn't want to get hit from behind by a driver that can't see me. I thought a long time on this and wanted to use a battery powered light that blinked.
I found a piece of old plumbing drain (a "T" joint) and mounted 2 small side lights and a 4" LED light I found at Harbor Freight (I love that place). It's all epoxied together and sprayed black. The drain T slides right over the seat shaft for a snug fit. There's a hole in the top for a flag staff. The wiring ends with a cigarette type connector for fast disconnect. I used a $3 blinker inline to make it flash.
I have a 12v lead acid battery from my photo flash equipment that can be recharged and is light enough to strap to the rack over the back wheel. You could probably use a bigger one.
Step 5: Carrying Options
This little trailer is pretty versatile. I put this plastic milk crate on for size comparison. The eyelets allow you to lash about anything on it.
CAUTION: This will not hold a person. Small dog, maybe. Trip to the store, most definitely. Trip to town or the beach with food and tune, yes.
Have fun and let's see what you can build.