I've seen several DIY bike cargo trailers and I had a burning desire to build one of my own. Oddly enough, I have no real reason for needing one. But, I didn't let that stop me. :)
Most of the DIY trailers have a non-adjustable platform for cargo. I decided I would use nylon webbing to construct an adjustable net for the cargo platform. It could be pulled tight to raise the center of gravity and loosened to lower it (for stability).
After browsing the local classifieds, I found this kid trailer for $20.
The last image is a preview of the completed cargo trailer. :D
Step 1: Tubing Damage...
I met the seller at dusk and I didn't inspect the trailer close enough. Once I had it home, I noticed damage to the tubing. Lesson learned... The tubing repair is outside the scope of this Instructable. However, if you're interested, detail on the repair can be found here: DIY Bike Cargo Trailer - HuckingKitty
Step 2: Remove Unnecessary Parts.
Using commonly available tools, I stripped the trailer down to the frame. I salvaged quite a few webbing components, aluminum supports, and hardware to be used in future projects.
Step 3: Measure for Cutting
I wanted to make the trailer narrower and still have it track straight. Since the pull-arm could be moved 3-1/2" out, I wanted to remove 7" from the overall frame width.
Step 4: Cutting the Frame
I used a cutting guide and hacksaw to remove 7" of the frame width. To reconnect the pieces, I had to find something that would snugly fit the inside diameter of the tubing. A wooden paint extension did fit; however, I wanted to use something other than wood. After trying several other options around the garage, I discovered that an old mountain bike handlebar was a perfect fit. I cut off two lengths and rejoined the cut sections.
Step 5: Relocate the Pull-arm and Reassemble
While the fame was apart, I relocated the base plate for the pull arm to the outer portion of the frame. I then reassembled the frame.
Step 6: Measure for Webbing
I'll be using 2" wide webbing and plastic tri-glide slides to build the cargo net.
I measured the frame inner width and length to determine how long the webbing pieces should be cut. I added 24" to each measurement to ensure I had extra slack that could be used to adjust the tension.
Step 7: Cut Webbing and Seal the Ends
I measured the webbing and cut several pieces for the net.
Cut nylon webbing will unravel unless you seal the ends. To do so, I setup a propane torch and passed each end of the webbing near the flame (direct flame contact is not necessary). You'll see the "hairs" melt and the end seal itself. This could also be done with a lighter.
Step 8: Net Design
I traced the inside of the frame onto a piece of cardboard (and made note of where the wheel supports were located). This was used to test out different net designs until I found one I was happy with.
Step 9: Net Construction
I arranged the webbing in a final configuration and used E6000 adhesive to glue the overlap points together. When finished, I arranged bricks on top of the straps and let it sit overnight to dry.
Step 10: (optional) Pad the Pull-arm Clamp
Since I had the E6000 adhesive out, I decided to also glue a piece of inner-tube to the pull-arm clamp. I hoped this would reduce any scratching to my bike frame when it's attached. After the adhesive dried, I used a razor to trim off the excess.
Step 11: Install Slides Onto the Net
I added a plastic slide to each piece of webbing extending from the net.
Step 12: Attach Net to the Frame
This sequence of photos shows the weaving pattern used to secure the net to the frame. Repeat for each piece of webbing.
Step 13: Finished Trailer
Photos of the completed trailer. With netting and wheels, it weighs in at 15#. 1-1/2# heavier than a Bob Yak trailer. And, the webbing can be loosened allowing the net to sag (creating a lower center of gravity).
Step 14: Taking It Out on a Test Ride!
I attached the trailer to my bike and loaded up 24# of bricks for the test ride. Aaaand away we go!
Be sure to watch for the surprise trailer flip near the end. ;)