Step 1: Material List
1 qty old bike fork
1 qty storage container of your choice. I used a 27 gal. Rubbermaid one from Costco
1 qty old bike wheel. The smaller the diameter the more it will tend to bounce over bumps
6-10 tech screws or any screw suitable for attaching your bin/container
1 qty child tag-a-long bike hitch. These are easy to make but so easily available why bother
? qty of wood for deck. What do you have laying around. I had a scrap of 3/8" plywood from another project
? qty of conduit, pipe, tubing or misc. metal. I used about 3 and 1/2 feet of 1/2" EMT electrical conduit and 3 and 1/2 feet of 3/4" EMT electrical conduit. I also used a small length of 1" square tubing because I had it and ran out of EMT. Use what you have.
4 qty pre-bent 90 degree elbows. You could weld straight 90's or use a tubing bender. I was going for maximum convenience in this step. They are pretty cheap from the hardware store.
4-6 qty bolts variety of lengths. I used some bolts to strengthen all the joints. I found misc ones that fit snug in the pipe, cut them to extend a couple inches into the joints and welded them all the way around. (probably over kill).
2-4 qty of plate steel. I used some scraps from my junk bin. They were brackets off some old equipment. The pieces I used were about 1/8" but you will need to use metal thickness based on the loads you intend to carry. There will be flexing at the joint if you go too thin.
Step 2: Prep and Assembly
To be safe I drilled some holes in the end of the fork and added some axle retainers (optional).
You will see from the picture I laid it out with 3/4" EMT to start (single tube). It was WAY to flexible so I added a second row of EMT and it worked perfectly. In hind sight I would have used two rows of 3/4" vs. the 1/2" and 3/4" combo. I also would have borrowed a bender and saved myself the welding. The dimensions will vary depending on your bike, fork and the wheel size. I eyeballed it to the frame so that it had generous wheel clearance for turning and camber changes. My goal was to keep the floor of the trailer level at rest. Go low so it handles well, but not so low it hits all the time. Mine is a little over 4" from the ground to it's lowest point.
If you had a tubing bender and new pipe this would be snap but I had to weld all the junctions together.
Step 3: Final Assembly, Paint and Storage Attachment
I used a 6mm bolt and some self tapping sheet metal screws to attach the wood deck. Then the bin was screwed on using self tapping sheet metal screws.
Finally some reflective tape and reflector added for visibility
Step 4: Test Drive and Handling Review
Some general observations and general notes about towing a trailer on a bike: If you have never towed a trailer with a bike, keep in mind how much more room you need to turn and stop. Your turning radius greatly increases with a rig like this. Also depending on how heavy and how high you load you may notice a top heavy feeling in cornering and stopping. I have found that up to about 40 lbs and under the lip of the storage container it handles great. The low center of gravity makes it almost unnoticeable. When you go very heavy (50, 60 lbs.+) you can notice flexing over the bumps. When it is empty or loaded lightly you get some bouncing over misc road bumps (not bad).
Over all I am very, very happy with my creation. We use it all the time. It takes seconds to attach and holds plenty. It is the perfect running errands trailer. I have only used it behind my tandem. It may handle even better behind a standard bike. We have a curvy down hill by our house and we scream down it on a regular basis with the trailer and it handles perfectly.