Introduction: Bicycle Trunk

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About: I enjoy hiking and plant foraging... but most of time I do chores!

To make this bicycle trunk / box / carrier, you'll need to use 3/8" x 6" wide wood. The length isn't too critical as long as the planks are long enough. You'll need the following tools:

  • Screwdriver
  • Hand Saw
  • Scroll Saw -or- Rasp

You'll also need:

  • Sandpaper
  • Boiled Linseed Oil
  • Paste Wax

Lastly, the following:

  • #6 Flat-Head Screws
  • #6 Wood Screws
  • #10 Flat-Head Screws
  • Hinges

Step 1: Removing Stickers

If you buy wood from a big-box store like I did, it'll come with stickers. Here's how to remove the stickers so that they don't disrupt finishing:

  1. Remove the sticker as best as possible
  2. Apply enough Goo Gone to the sticker so that it isn't completely absorbed by the wood
  3. After soaking, wipe clean
  4. Heat the area up with a heatgun or embossing tool to dry

Step 2: Wood Joining

I'm not an expert woodworker, so all alternatives are welcome, but here is how I joined the pieces of wood to form the box shape and avoiding clamps:

  1. Measure the wood thickness. It is 3/8" and is assumed uniform
  2. Measure 3/16" from the edges of the wood and make marks
  3. Connect the marks to create a line along the edge, 3/16" from the end
  4. Measure 1.5" from an end along the newly drawn line and mark
  5. Create an indent in the wood with a scoring tool (sharp point)
  6. Drill 1/16" hole using a drill press (for straightness)
  7. Repeat the above process for all other edges
  8. Use a square or block to align the drilled wood edge
  9. Drill through to connect the two pieces using a hand drill
  10. Screw in a #6 flat-head screw to bind the two pieces
  11. Repeat Steps [8-10] for all other holes
  12. Unscrew all screws so that only tips show
  13. Apply outdoor wood glue the edges
  14. Tighten screws to clamp
  15. Let it dry

Step 3: Create Box

In this step, the previous methods are used to create a box:

  1. Cut pieces to size
  2. Mark and drill edges with drill press
  3. Use a table and wood block to align to edges
  4. Drill holes through using hand drill
  5. Unscrew screws to tips
  6. Glue using waterproof glue
  7. Let dry
  8. Remove screws for sanding

Step 4: Add Cutout

If you're not a dope like me you'll probably do this between step #1-#3. You have to add a cutout for the seat because the seat should not touch the box.

  1. Saw the cutout
  2. Cover cutout with more 3/8" wood

Step 5: Add Hinges

In this step, the hinges are added:

  1. Tape the lid to the box to keep it from moving
  2. Mark around the bulging / non-flat part of the lid with a pencil
  3. Use a utility knife to remove the marked portion
  4. Lay the hinge onto the lid
  5. Trace the hinge holes
  6. Dent the hinge holes
  7. Drill the hinge holes using a drill press

Step 6: Lock

In this step, a spring loaded locking mechanism is made. The mechanism should be spring loaded to hold the lock against the lid to suppress vibration while the bicycle is moving. It won't be absolutely quiet since a wooden box is a lot like the body of a guitar and can amplify(?) some sounds, but it definitely helps:

  1. Bend a #6-32 rod around a 1/4-20TPI screw
  2. Drill a hole in the back-center of the box so that the #6-32 u-bent rod can slide freely
  3. Drill a hole through a scrap piece of wood so that the #6-32 u-bent rod can slide freely
  4. Glue the scrap piece of wood to the inside of the box

The locking mechanism works like this:

  1. The lock attaches to the top of the u-bend
  2. The two top nuts act to lock each other in place
  3. The washers increase surface area for force / reduce stress on the wood
  4. The bottom spring pulls the u-bend down

Step 7: Complete Lid

In this step, the lid is completed with a metal guard to prevent the lock from denting the wood:

  1. Use a #6-32 rod to put a dent into the lid by putting it into the locking mechanism hole and letting it stick out while closing the lid.
  2. Drill the dent.
  3. Mark parallel lines towards the dent.
  4. Cut, saw, or file towards the dent.
  5. Cut a large fender washer into 4 parts with a hacksaw
  6. Epoxy two quarter-parts to the slot

Step 8: Finishing Up

In this step, apply finishing touches:

  1. Countersink the holes with a hand drill. The hole width should be slightly smaller than the width of the wood screw's head and be barely deep enough to make it flush
  2. Mark and drill holes for the frame clips. The frame clips are actually ground wire posts that can be found in the electrical isle of the many hardware stores.
  3. Sand any rough edges.
  4. Apply 3-5 coats of boiled linseed oil, once per day. Allow a week to dry. Let the oil soak for 20-30 minutes per coat before drying with a paper towel. Don't throw the towel away until garbage collection day, let it soak in a bucket of water until then to prevent spontaneous self-combustion.
  5. After step #4 is complete, apply 2-3 coats of paste wax. Allow a day to dry between coats.
  6. Assemble the box.

Step 9: Mounting

In this step, attach the locking mechanism and mount the box to the bicycle:

  1. Attach the locking mechanism. The top two nuts can be moved up or down and locked together so that the u-bend can stick out at an appropriate level. When the lid is closed, it should require some effort to put the the lock into the u-bend.
  2. Detach the luggage carrier from the bicycle and mount the box. Use washers as spacers to provide an offset. You may want to use more than one of clip per screw for increased strength.
  3. Close the box and attach the lock.

As a final note, there will be some rattling when the box is loaded with things. They'll bounce around. You can reduce this by padding the inside of the box with towels or napkins.