Using a bike is a great way to zip around town and run errands, but some jobs are a little more than a bike alone can handle. What about carting around jugs of water or groceries? How do you get power tools to a friends' house to work on a project? A backpack can only hold so much!
A bike trailer would be very useful, but what if you can't afford a spiffy new one from the bike shop?
This design can be built using scavenged wood, 2 bike tires, a few borrowed tools, and about $7 worth of braces that can be purchased at your local hardware store!
Step 1: Materials Needed
Here is what you will need:''
2 Wooden pallets
(Pallets are an industrial waste product that many businesses throw away. Check with local businesses, free pallets are available in most areas.)
(2x4 or 2x6 lumber works the best. 2 or 3 feet of 2x4 should work fine.)
2 Bike Tires
(Check with your local bike shop, garage sales, police auctions, etc.)
From the Hardware store:''
2 x 3/8" hex bolts (6 1/2" long with nuts and 2 washers for each bolt)
2 x 5/16" carriage bolts (With wing nuts and 1 washer for each bolt)
2 x 2 1/2" Corner braces (See pictures of hitch assembly)
1/2 lb. 2 1/4" Wood Screws
Suggested tools to borrow from a friend:''
1 Circular saw (Skil saw)
1 Pry bar
1 Cordless drill with multiple drill bits and screw bit
1 Band saw or jig saw
Safety Goggles, hearing protection, work gloves
Step 2: Pallet Deconstruction
1 pallet needs to be completely disassembled, the other will be partly disassembled and used for the body of the trailer. Using only a pry bar or hammer to take apart the pallets is usually very difficult and will usually crack the boards. This plan strongly recommends using a circular saw first to separate the boards.
A pallet usually consists of 3 "2x4's" with 1/2" thick boards nailed across them. To disassemble the first pallet, use a circular saw to cut the top boards along the edges where they are nailed to the 2x4s. (Be careful to avoid any nails and try not to cut into the 2x4s)
After the top boards are cut away from the 2x4s on one side, use the thongs on the back of the hammer to knock out the wood blocks from between the nails. Use a pry bar to take out the nails. (A pry bar is recommended for removing nails due to extra leverage.)
Flip the pallet over, repeat the process until you have 3 2x4's and a pile of pallet wood.
Disassembling the second pallet:''
It is important to keep half of the pallet in tact. Cut away one of the side 2x4s and the top and bottom boards that joined it to the rest of the pallet. The remaining part of the pallet will be used for the body of the bike trailer. Use the same process on the separated 2x4 to remove the nails.
After pallet deconstruction you should have:
1 Trailer body that is 1/2 of a pallet, roughly 20" wide (wider or narrower is fine)
A stack of pallet wood (This won't be used for the trailer and makes good wood for projects if you run it through a planer.)
Pallet nails (These won't be used for the trailer, but can be straightened and reused.) ''
Step 3: Wheel Assembly
For the wheel assembly you will need:
2 x Bike wheels
2 x 3/8" hex bolts with 2 washers and a nut for each bolt (The bolts are 6 1/2" long)
2 x 2x4s (Approximately 48 inches long)
4 x Wood blocks from scrap wood (Ideally 2x4 pieces, all cut into 3 1/4 inch wide blocks)
1 x Bag of 2 1/4" Wood screws
1 x Cordless drill with a 3/8" drill bit and a smaller bit for pre-drilling screw holes
1. Remove any bolts from the middle of the bike tires using wrenches and a lubricant such as WD-40.
2. Select 2 of the 48" 2x4s to be the rails for the wheel assembly. Next measure in 23" from one end of the 2x4 and make a mark for drilling. (Make the mark close to the middle of the board, around 1 3/4" from the top on the flat side of the 2x4.) Drill a hole through the mark with the 3/8" drill bit, try to keep the drill as straight as possible. After drilling the first hole, lean the trailer body up on one side and place the 2x4 on top of the side. Line up the 2x4 with the trailer body edge. Drill through the first hole in the rail and into the 2x4 on the side of the trailer body. Try pushing the 3/8" hex bolt through the holes to see if it will fit. Use the drill to bore the holes slightly wider until the bolt fits through both holes easily.
3. Place 4 of the 3 1/2" wide block between the rail and the trailer body. Slip one of the bike wheels into the center where the bolt hole was drilled. Place 2 of the blocks at each end of the rail, connecting it to the trailer body. Place 2 of the 3 1/2" blocks closer to the wheel for added support. Remove the wheel and predrill 2 holes through the rail at each location of a wood block. Secure the rail to the blocks using woodscrews in the pre drilled holes. Flip the rail and trailer body over on to the other side and predrill holes to secure the block/rail assembly to the trailer body. Secure the woodblocks to the trailer body using 2 wood screws for each block.
4. Repeat steps 2 and 3 for the rail on the opposite side of the trailer.
5. Flip the trailer body on one side and use the 3/8" hex bolts to check that the bolt holes fit. Install the wheel by securing it through the bolt with one washer on each end of the bolt and with the nut secured on the inside of the trailer body. Tighten the nut until there is very little gap between the wheel and the rail. Loosen slightly if the wheel won't turn. Flip the trailer on the other side and secure the other wheel using the same process.
Step 4: Making the Hitch Assembly
2 x Remaining 2x4s from the deconstructed pallet
2 or 3 feet of 2x4 wood scraps
(It may be easier to remove the wheels so that the trailer assembly will lie flat on the ground.)
1. You will need to cut 4 pieces of 2x4 to complete the hitch assembly. For the front crosspiece, measure the width of the trailer body without'' including the side rails and cut a piece to attach to the face. (It should be somewhere around 20".
2. Cut a piece for the upright that attaches at the base to the crosspiece. Use your bike to determine how high this should be. The hitch will attach to the metal post underneath the seat. The upright should measure around 19" or 20".
3. Cut the diagonal piece that will brace the hitch. It should be 24" long. Use a speed square, combo square, or protractor to draw a 45 degree line on each end and cut with the circular saw.
3. For the top connector you will need one of the 48" 2x4s from the deconstructed pallet. Depending on the size of your bike, you may want to shorten this piece to around 42" or 44". Use your bike as a reference to check this distance, bearing in mind that your rear wheel will need to be clear of the diagonal piece. (See finished trailer picture.) Save one of the triangle pieces that are left over from the 45 degree cuts.
4. Secure the front crosspiece to the face of the trailer using wood screws. (Pre-drill the holes for the screws.)
5. Position the upright piece roughly in the center of the crosspiece and screw it in at the base.
6. Ask a friend to hold the long connector piece on top of the upright. Secure with screws. Insert the triangle piece underneath the joint and secure with screws. Use the angle braces to secure the joint on the sides. (Your friend can let go now.)
7. (Optional) To make the hitch assembly more stable, you may with to secure it with 2 additional angle braces on the inside joint next to the triangle block.
8. From the 2x4 wood scrap, locate two pieces and cut them at 6" each. Using your bike, trace a circle in the middle that is slightly wider than the post under the seat. (There should be half of a circle on each block of wood so that they form a whole circle when placed together.) Cut out the half circles on each piece using a band saw or jig saw. (The turns may be too sharp for a band saw, try cutting the circle out in small sections if this is the case. It doesn't need to be perfectly round.)
9. Hold the two 6" blocks together lengthwise. Make marks for boring the bolt holes by checking the blocks against the end of the connector piece of the hitch. (The bolt locations should be easily wider than the connector that will attach in the middle.) Bore holes through both pieces of wood with a 5/16" or slightly larger drill bit. (This is a little tricky, You can bore through the first piece so that the tip of the bit marks a hole on the other side. Remove the top block and drill the rest of the way through the second block.) Repeat this process for the other side. The holes may need to be widened slightly so that the bolts will fit through both blocks. Secure the bolts temporarily with the 5/16" bolts with the washer and wing nut at the end.
10. Attach the 6" block assembly to the connector piece of the hitch by attaching a block across the top of both pieces. Screw the top block into both pieces. Make sure that this connection is very strong.
Step 5: Enjoy!
Go slow at first when pulling your trailer with a bike. If the wheels squeak, some lubricant may be needed on the wheel bolts.
Drilling holes through the boards is a great way to secure items to the trailer using bungee chords. You may also want to make a box from left over pallet wood for carrying tools and smaller items. (A wood box works great for carrying jugs of milk or water.)
Be careful with the amount of weight placed on the trailer. (The weight of an adult may be enough force to break the hitch.) The base where the hitch attaches to the trailer body is the most vulnerable joint. This design has successfully transported small pieces of furniture and up to 2 wooden pallets.
Engineerical made it!