Sociable Tandem Cargo Trike





Introduction: Sociable Tandem Cargo Trike

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This side-by-side, or "sociable" tandem trike was conceived and built so that two friends could sit next to one another, pedaling and enjoying the scenery. To share conversation and beverages. Drink holders are an obvious feature, but let's look at what this particular SociableTandemCargo Trike has to offer.

  1. Adjustable, semi-recumbent, side by side seating.
  2. Shared steering wand with solar stereo option.
  3. 15 speeds to choose from.
  4. Disc brakes on all 3 wheels, and a parking brake.
  5. A seat and cargo area in the back, that will carry 150 lbs. of whatever you choose.
  6. Roof rack with bungie hooks for light items or a solar panel.
  7. Standard parts, wheels and components whenever possible, to make this easy to build and fix.

This Instructable is for intermediate/advanced "Makers," who already have a working knowledge of metal working, bike building, basic engineering, and woodworking skills. It took us about 4 months from start to finish. There are 2 of us, but we did not work every day on this project, mostly weekends.

If you need more specific instructions, or have questions about where to get materials, visit us at Pineapple Trikes, our FaceBook Pineapple Trikes page, or email us.

Let's get started!

Step 1: Design Your Sociable Tandem Cargo Trike

Design your model in a 3-D program, such as Google's free SketchUp software. The link to our model is here.

You can also build a wire model, like the one we built for the trike, using welding wire stick and weld tacks.

Step 2: Acquire Your Materials

General Materials List


20 feet of 1" round tubing

20 feet of 2" round tubing

20 feet of 1 1/4" round tubing

small piece of 1/4" flat metal

1 sheet expandable metal mesh

10 ft. of 3/4 inch emt


1 sheet of 1/4" plywood

1 sheet of 1" plywood

Recycled bike parts:

One front end of a bike, trimmed down to the headset, head-tube and forks.

6 bottom brackets - 2 with viable pedals, cranks, bearings, etc.

2 twist-shifters for the back derailleurs

3 disc brake assemblies

3 sets of caliper brake mounting assemblies

2 sets of "suicide shifters" for the front derailleurs

6 complete chains


zip ties



6 - 4" long -3/4" bolts, washers and nuts


shade cloth

brake cables, stops, cable ferrule ends and sheathing

shifter cables, stops, sheathing

Paint and Finishes:

about 3 cans of metal primer spray paint

about 6 cans of whatever color you will paint your trike.

*optional: 2-Part Epoxy finish, such as "SmartGlaze."

Step 3: Tools, Equipment, Workspace and Expertise

This is where we re-iterate that you should be an experienced builder to attempt this Instructable. We are assuming a working knowledge of metal and wood. We hope you have a space, albeit a garage, to work in so that your project stands a chance of surviving the elements. Our shop is an E7-Up, but we face many extra challenges because of all the dirt and exposure.

You will need a welder- we use a wire-feed MIG. A tubing-roller and a conduit bender are also going to be essential. We use this one from Harbor Freight. Tables, sawhorses and tarps can also be instrumental.

You need to have basic wood and metal shop tools including: angle grinder, jigsaw, hacksaw, sawsall, pliers, socket-set, sander, drills, bits, wire brushes, wire wheels, a flap disc, grinding wheels, cutting wheels, etc.

Step 4: Bend Your Tubing

If you don't have a tubing roller or emt bender, you can go to our other Instructable, "How to bend metal without expensive tools."

If you've got a CAD model, getting dimensions is straightforward. If you built a physical model, such as our wire model, here's a handy formula for calculating your curves: measure h (the height of the chord) and c (the length of the chord) and solve for the radius of the circle with

r = (c^2 + 4 h^2)/8h

One of our curves is 3" high (h) and 48" long (c). Here's the size of that radius:

r = (48*48 + 3*(4*4))/8*3

r = (2304 + 48)/24

r = 98"

Make a template with a 98" radius and you can hold it up to your tube as you bend it for comparison.

Here's a tip for not making corkscrews

Step 5: Lay Out and Weld Up Your Frame

Because this is a large frame, you will need a couple of large tables to set up your frame. We used yardsticks, masking tape, and other props to function as a jig, for holding our frame pieces together.

A great rule to follow is to tack all the pieces together before you weld anything all the way. That way, you can make sure things line up, and are fairly symmetrical.

Cut and weld bottom brackets to the frame.

Step 6: Adding Adjustable Wheel Dropouts

In order to adjust the wheels so that they stayed parallel, we attached a home-made tensioner, made from a hardware store turnbuckle, attached to the wheel, and to a bolt welded to the frame.

Step 7: Make and Attach Jack Axles to the Frame

This will get the chains to line up with the wheels. We used heavy duty tires that are used by Yuba bikes for their Mundo model. The spokes are heavier than regular spokes, and the tires are rated for around 300 lbs. apiece.

Step 8: Attach Seat Runners to Frame

For our build we realized that the headset from a BMX bike was the perfect size to hold a seat tube (28mm diameter.) Our seats, with their 3/4 inch bottom seat support fit nicely into the handlebar clamp. The result is a solid, adjustable mounting point to accommodate different lengths of rider's legs.

Step 9: Seat Construction

We found this guy online, (Seat frame construction, by Barnett Williams,) and followed his plans. The seats are brilliant!

Step 10: Welding on the Disc Brake Attachments

We cut out a flat metal pattern that the disc brake can screw right into.

You might also be able to find forks that already have disc brake attachments on them for the front, but will have to attach metal for the back. We repurposed caliper brake attachments, because they took the same size hex nuts as the disc brake attachments.

Step 11: Build the Non-heirarchical Steering Tiller

Measure the distance from where you will sit in the seats, with your arm comfortably extended, to the headpost. You will want to bend the tiller into the shape seen in the photo, above. We used emt, with two crosspieces in the front. One is for attaching to the headset, and one is for attaching a light. We also reinforce our tiller with expandable metal mesh. It is nice for strapping on mini solar panels and stereo stuff.

Step 12: Shifters, Brakes, Cables and Sheaths

Attach cables and sheath with zip ties. When you get them all working the way you want, weld on some cable stays in strategic spots, then you can run the cables without zip ties after you paint the frame.

Step 13: Build the Roof Rack

Build the roof rack, weld in 3 frame attachment points and sew a cover that can be cinched on with paracord.

Step 14: Build the Back Cargo Seat

Frame the back area up with EMT, on a metal mesh base. We made a removable box, bolted on to the frame in 4 places. Weld washers onto the frame, and you can drill guide holes, and then pop rivet the plywood on.

The plywood is treated with 2-part Bar Top epoxy. Smart Glaze is one brand that we like. We painted the glaze over the wood and the frame, as a protective coating.

Step 15: Design a Great Color Scheme

The simplest way to get an amazing color scheme is to borrow one from Nature. Choose a lovely bird, flower or butterfly and copy not only its colors, but also how much of each color as well as noticing how those colors are arranged.

Here, with some liberties taken for simplicity, is an Adelpha Californica's scheme revealed: it's overwhelmingly a rich chocolatey brown (around 70%), with (in descending proportions) cream, orange and gun metal blue/gray (most of the remaining 30%). A hint of red and black finishes it off. Especially important to notice is that not all the colors are "allowed" to touch. Orange only touches brown, while black touches red and brown and gray. Following these sorts of rules nails the "Wow" factor.

For our trike, we took inspiration from Buckeyes and Fritillaries.

Go right ahead and swap yellow for blue, or red for brown; the important thing is to create a consistent set of rules for your bike (or other project)

Step 16: Strip the Trike, Prep and Paint

Strip all the parts off the frame, group and label them so they can be put back on easily.

Grind and wire brush all the rust and slag off the frame.

Prime with a decent metal primer

Paint with a few coats of spray paint, and let cure, optimally in the fresh air and sun.

After a day or two, brush on a layer of two part epoxy. It will put a clear finish over your color that will make it glossy and with stand bumps and scrapes better.

This rattle can and epoxy paint job cost about $100. Here's a great video about how to paint with a rattle can.

Step 17: Reassemble Everything, and Go for a Ride!



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    This is really cool. It looks so comfortable. Did you enter it in the bike contest?

    Thank you! Yes, we've entered it! Please vote for us! :)

    This trike is very comfortable. Sitting like a normal person instead of perched up on your bones is quite pleasant.


    Wow, your Batman costume is amazeballs!

    Hi, I found your design very interesting.I liked it and I'm looking forward to make one myself. I realized you haven't say which metal you used for the frame. Was it steel, aluminum or other? Please let me know. Thanks

    So I'm curious about the drive system and spindles. What did you use the spindles off of? I dont see anything about them listed in your parts list. I'l love to learn a little more about how you built that part

    Have you been to the Maker Faire in the bay area?

    As a matter of fact, yes we have! We'll be there this year as well. Look for us in the South Lot!

    This is absolutely amazing, I entered in contest with my trailer and my vote goes for this project! Congrats!