Introduction: Flatbed Bicycle Trailer
A bicycle trailer is a great way to increase the carrying capacity of a bicycle. This tutorial will show how to create a flatbed bicycle trailer using recycled items without the need to weld.
Step 1: Repurpose Items Destined for the Landfill
I picked up an old baby stroller that was well used but no longer functional. I instantly knew that I wanted to make a bicycle trailer with it. I also was able to use parts off of an old golf caddy to make the arm that connects the trailer to the back of the bicycle.
It is always a bonus to make things using discarded items and give them new life.
Step 2: Remove Unneeded Components From the Stroller
To create the bed of the trailer, start by removing the handle from the stroller and then remove the footrest from the handle.
The footrest is attached with rivets. To remove the rivets, I used an electric drill and a self-drilling sheet metal screw to drill through the rivet head. It works just as well as using a drill bit and it saves my drill bits from wear. With just a small amount of drilling, the rivet head falls off as seen in Photo 1.
Next use a small punch to drive the rivet body into the tube and free the footrest from the stroller handle (Photo 2).
Remove the cushion grip from the stroller handle and remove the hook and loop fasteners from the handle as seen in Photo 3. The handle will be used to form the frame of the trailer bed.
Step 3: Attaching the Outer Frame to Trailer
The next step is to attach the handle to the trailer to form the outer rim of the trailer bed.
At this point you may wish to cut off some of the end of the handle to form a shorter flatbed trailer. For now I left the handle as is to see how well I like a longer flatbed trailer.
Use four screw clamps large enough to clamp the handle to the existing part of the trailer frame (Photo 1).
Start with one leg of the handle and clamp it to the short outer portion of the frame using two of the screw clamps. Once attached, connect the other leg to the opposite side. Ensure that the screw heads are placed on the underside of the trailer bed as seen in Photo 2.
With the handle firmly attached to the short segments of the trailer, drill two holes .25 inches (6.5 mm) diameter through both tubes on one side of the trailer (Photo 3), insert bolts in the holes then secure with a nut as seen in Photo 4. Repeat for the other side of the trailer bed frame.
The outer frame of the trailer is now complete as seen on Photo 5.
Step 4: Attaching the Inner Supports to the Frame
Now that the frame is in place use a threaded rod to connect the two inner supports to the frame. The size of the threaded rod will depend on the hole size of the fittings. Mine allowed me to use a .25 inch (6.5 mm) diameter threaded rod.
Starting from one side, insert the threaded rod through the plastic fittings and place washers and nuts on either side of the plastic fittings as you insert the threaded rod (Photo 1).
Once the rod is inserted through the inner supports and the frame, tighten the nuts and cut off the excess threaded rod as seen in Photo 2.
The trailer bed supports are now united.
Step 5: Making the Arm That Connects the Trailer to the Bike
The arm that connects the trailer to the bike is made from the leg of a nonfunctional golf caddy (Photo 1).
Start by removing the leg from the golf caddy and remove all unneeded components as seen in Photo 2.
Take a .75 inch (19mm) conduit support (Photo 3) and use a hammer to flatten the base of the support so that it appears as shown in Photo 4. Do the same for a 1 inch (25 mm) conduit support. Flatten one more of both sizes.
Attach the arm to the outer rim of the trailer frame and secure with the flattened conduit supports. Use existing holes or drill new holes into the edge of the trailer arm as seen in Photo 5. Insert the smaller of the flattened supports and insert a .25 inch (6.5mm) diameter bolt, 2 inch (52 mm) long, through the flattened support and then into the trailer arm (Photo 5). Next place the larger of the flattened supports directly on the top of the smaller flattened support as seen in Photo 6 and secure with the bolt. Place a nut on the bolt and tighten. Place a second set of flattened supports midway along the arm.
Use a U-bolt, placed on the arm at the farthest point possible to connect the trailer arm to the trailer frame as seen in Photo 7.
The arm is now attached to the flatbed trailer frame.
Step 6: Making the Trailer Hitch
The trailer hitch is probably the most interesting and challenging part to create so as to provide a secure but flexible connection. Thanks to the many authors on this site, and elsewhere who shared their creations and ideas, I was able to weigh the pros and cons of the various types of trailer hitches and eventually settled on a hitch that uses two casters to make a trailer hitch. This type of trailer hitch allows for three-directional movement and is ideal for trailers with two wheels as it allows for better handling over uneven terrain and for making turns.
Start by removing the wheels from two casters as seen in Photos 1 and 2.
One of the casters is attached to the bike frame and the other is attached to the arm of the trailer. The casters are attached to each other with a hitch pin as seen in Photo 3.
Step 7: Attaching the Casters to the Bike Frame and the Trailer Arm
Attach one of the casters to the rear of the bike on the left side as seen in Photo 1. I was fortunate in that existing threaded holes on my bike matched the mounting holes on the caster. If necessary, drill holes in the base of the caster to match mounting holes on your bike. Use existing holes in the caster and drill only what is needed. Attach with the appropriate-sized bolts that match your bike. I used bushings as spacers to keep the caster mounted in a level position.
Take the other caster and use two .5 inch (13 mm) conduit support brackets to connect the end of the trailer arm to the caster (Photo 2).
Finally use a hitch pin to connect the two casters together as seen in Photo 3. The hitch pin allows for a quick and convenient way to connect and disconnect the trailer and bike.
The three-directional movement of the hitch allows the bicycle and trailer to move, sway and pitch without greatly affecting the other. As seen in Photos 4-6, the bicycle can lie on the ground, on either side, while the connected flatbed trailer remains unaffected and upright.
Step 8: Attaching a Safety Catch Cable Between the Bicycle and Trailer
A safety catch cable is connected to the bike frame and the trailer and is designed to "catch" or constrain the trailer if the hitch should come apart. A hitch may come apart if the fastener fails or the hitch pin was improperly connected.
The stroller did have a cable-activated side caliper brake, as seen in Photo 1, which is perfect for making the safety catch cable. Disconnect the caliper brake but leave the brake lever in place as it has a mounting bracket that will be used to mount the cable to the trailer frame.
The best way to contain the cable itself is to locate it within the trailer arm.
To do this, enlarge an existing hole near the end of the trailer arm (Photo 2) and run the cable through the hollow trailer arm and pull it out of the trailer arm through the enlarged hole (Photo 3).
As seen in Photo 4, cut about 4 inches (102 mm) of the cable housing to expose the cable.
Use a cable ferrule to create a loop in the cable and crimp the ferrule with a crimping tool as seen in Photo 5.
Loosely wind the looped cable through the end of the trailer arm and attach to a steel carabiner that is attached to the bicycle frame (Photos 6 & 7). Ensure that the cable is loose enough so that it does not interfere with the movement of the trailer hitch.
Attach the other end of the cable to the bicycle frame as seen in Photo 8.
The safety catch cable is now in place and ready for inspection (Photo 9).
Step 9: Making the Wooden Flatbed
In keeping with the underlying theme of reusing discarded items, I chose to use wood salvaged from unwanted oak pallets to make the wooden flatbed.
You will need enough boards to cover the length of the trailer frame. In addition you will need three shorter boards for supports.
Start by separating suitable boards from a pallet free from oil or other contaminants as seen in Photo 1.
Sand the boards and lay faceup with a space of about .5 inches (13 mm) between the boards. Place one of the short support boards underneath the long boards roughly 2 inches (51 mm) from the top of the long boards, oriented perpendicular to the long boards as seen in Photo 2. Draw lines where the boards intersect and label as needed.
Flip the boards facedown and reposition. Drill holes through the short board into the long boards below taking care not to drill completely through the lower boards. The hole should be just slightly smaller in diameter than the diameter of the screw you are using to fasten the boards together (Photo 3).
Once you have the short board fastened to the top of the three long boards, place a second short board at the bottom of the long boards just as was done with the first short board and fasten as seen in Photo 4.
Finally place the third short board midway between the two short boards and fasten (Photo 5).
To further strengthen the flatbed, I drilled holes through the boards and attached bolts .25 inches (6 mm) in diameter and 2 inches long (51 mm) long. I used two bolts per board at each place where the board was supported by the short board as seen in Photo 6.
As seen in Photo 7, I made sure to place the location of the bolts so that the bolt would also secure the fasteners which secure the flatbed to the trailer frame.
Step 10: Adding Reflectors
To finish the trailer, add reflectors to the rear of the trailer. Start by cutting a board 14 inches (356 mm) long and attach it to the end of the flatbed trailer with a hinge as seen in Photo 1.
Flip the flatbed rightside up and place two reflectors and secure with wood screws as seen in Photo 2.
Photos 3 and 4 show how the reflectors add visibility during the day and night.
Step 11: Securing the Flatbed to the Frame
Place the flatbed on the bicycle trailer, and align into its final position on the trailer frame as seen in Photo 1.
Secure the wooden flatbed to the frame with .75 inch (19mm) and 1 inch (25 mm) conduit supports (Photo 2) to fasten the wooden platform to the trailer frame.
The Flatbed Bicycle Trailer is done!
Step 12: Safety Considerations
It is a good idea to practice towing the flatbed bicycle trailer, making right and left turns and braking. It is best to ride in areas with bicycle lanes or roads with wide shoulders.
The flatbed bicycle trailer is made primarily for loads that are lightweight. I made this flatbed trailer without sidewalls to keep the weight down, relying on straps to secure the load.
My plan is to use it to primarily haul groceries, lightweight building materials and recycling/garbage items.
Hauling loads that are too heavy would most likely be damaging to the aluminum frame. The wheels have steel rims but again, the original design was a stroller for a young child. All of the fasteners used to construct the trailer are steel but not rated for use in constructing a trailer.
Hauling anything too heavy could result in failure of the trailer, fasteners and connectors. Any failure while in motion could result in injuries and damaged goods.
Hauling heavy loads would also affect handling of the bicycle while in motion and increase braking distances.
Step 13: Maintenance
Keeping up with trailer maintenance is another way to stay safe.
Because this is a no-weld project there are numerous fasteners with screws and bolts. While lock washers and lock bolts were used for most fasteners, the vibrations from riding on smooth and rough roads may cause some of the fasteners to loosen over time. Therefore it is important to check fasteners periodically and retighten as needed.
Maintaining proper air pressure in the tires is important as well.
Step 14: Final Thoughts
The Flatbed Bicycle Trailer is easy to make using hand tools and an electric drill. Using discarded items keeps costs down and allows us to do our part in reducing contributions to the landfill.
Best of all, the Flatbed Bicycle Trailer allows us to expand our use of the bicycle in that we can transport lightweight items that are large and bulky. Using our bicycles instead of cars whenever we can is always a good thing.