This project was part of an undergrad design class where we wanted to make cheap bicycles more utilitarian. My goal was to make something that you could produce in a dorm room, but would hold 3 people.
I used a 3 speed, gear-hub, girls bike, but you could probably adapt the simple design to work with any bike. The end result is pretty goofy looking but very effective at hauling people and cargo. You can find a bike like this for $15 at goodwill and should plan on spending $10 on the bolts and wood.
Step 1: Tools and Materials
This is what you need:
1" paddle bit
1/2" twist drill bit
x4 lag bolts, nuts, and washers
x2 6 foot long 2x4s
( you may also want a spokeshave/ sanding block to shape the peddling area and a coping/ jigsaw to cut out the front brake area )
Step 2: Marking
Hold the 2x4 against the frame and mark what you'll need to notch out. You need to make sure that the front brake has clearance to move when you turn the handlebars. Leave some room for the brake and gear shift cables too so they don't get crushed.
Step 3: Notching and Drilling
Cut out half of the thickness where the frame goes, but make the cut for the front brakes all the way through. Drill the countersinks for the washers and nuts before cutting the bolt holes all the way through.
Step 4: Finishing Touches
In order to make the rack more useful and user friendly, I added some special features.:
- Rows of holes along the top edge of each side so you can temporarily jam in bamboo sticks or dowels to make more of a table like surface (for carrying a stack of pizza boxes)
- I also shaped the part of the rack where it sits between your legs, so that if you do accidentally brush against it while peddling, you won't be hitting a corner, just a nice rounded edge.
- The lower half of the rack's ends are tapered, just so it doesn't look like a battering ram.