Bicycle Cargo Trailer

Have you ever wanted to take something extra with you when you ride your bike, but didn't know how you could get it on the bike and still be able to ride?  I have, and believe me one of my favorite challenges about bike riding is figuring out how to strap anything from a tennis racket to a load of firewood to a bike.  There is something about that moment when you wrap that bungee cord around your item just right, pull on it until your fingers hurt, and get it to hook on.  You step back and think to yourself "this is rigged but it just might stay on."

In my effort to carry more things with my bike I decided to build a cargo trailer.  It wasn't going to be a typical trailer though, I wanted something that was Heavy Duty, maybe something that could handle most household appliances.  So I got started just like every other good home made bike trailer, with a pair of garbage picked wheels and a set of tires that were given to me for free.

Here is a quick run down of the main features of the trailer:

1. Large 28"x41" deck
2. Mounts with a quick release ball joint to any bike rack
3. 1" square steel tube frame can accommodate up to 700c/29" wheels and tires
4. 100mm drop out spacing to allow for most bicycle front wheels
5. Space for tool box with tools, straps, and bungee cords
6. Adjustable pulling arm to allow mounting to any bike

My main motivation for building this trailer came from the many "bike move" videos and blog posts on this topic.  A bike move is what it sounds like, moving to a new house by only using bikes for transportation and hauling.  This requires cargo bikes, bike trailers and the blank stares of people as you ride past with a massive load of  stuff on your bike.  This video is my favorite bike move video from a group of bike movers in Bozeman.  This is not me or my video, but it is a great example of what can be done with a bike trailer.

       
There is also a great post on the Utility Cycling blog about this bike move, Bike Move!

If you just watched the video your probably wondering, How much can I really tow with a bike?  Well the company www.bikesatwork.com sells cargo bike trailers and has some great references on hauling large items on bikes.  Check out the How much can I haul?  page for a calculator on towing weight.  They state that "...most people can comfortably pull 300 lbs (137 kg) with a typical mountain bike and cargo trailer..."  Also check out these links for bike gearing and moving advice, Hauling Cargo by bike  I have not purchased anything from this company but from the info they give and the pictures of their trailers in action I believe they sell a good product, but its just a little pricey.

So now that you see the potential behind a simple bike trailer, lets go build one!

NOTE: In order to use this bike trailer you must have a bike rack
         

Step 1: Tools, Materials, and Plans

Here is a list of the tools and materials you will need to by this bike trailer.

Tools

1. 4.5" Angle Grinder with cutoff, grinding, and sanding discs
2. Drill Press with vice or C-clamp (not absolutely needed but makes drilling steel MUCH easier)
3. Drill Bits size 1/4", 5/16" and 3/8"
4. 3/8"-16 Tap
5. Center Punch
6. Hammer
7. Welder ( I am currently using the 90amp flux core welder from Harbor Freight ~$100)
8. Welding gloves and helmet 
9. Tape Measure
10. Sharpie

Materials

1. 1" Square tube steel ( I got most of the steel for this trailer from an old BBQ grill and a bench press stand)
2. 2" x 3/16" steel flat bar ~1ft long
3. 1" x 3/16" steel flat bar ~1ft long
4. 3/8"-24 threaded rod ~1.5" long (This is a fine thread size, and could come from an old bike axle, many of which are this thread size, or just cut off the head of a bolt of this size)
5. QTY 2 -  3/8"-24 nuts (might also be able to use bike axle nuts)
6. QTY 4 - 1/4"-20 x 2" long bolts with nuts and washers
7. QTY 2 - 3/8"-16 x 1.5" long bolts with nuts and washers
8. QTY 4 - 5/16"-18 Eye bolts with nuts and washers
9. ~ 28"x41" piece of 3/4" MDF (This is for the deck of the trailer and you can use what ever you want for this)
10. Quick Disconnect Ball Linkage (McMaster part #6058K34)
11. QTY 2 - Bike wheels and tires ( I used 20" wheels, but the frame design allows for larger 700c wheels)

Thats it, aside from the quick disconnect linkage all items can be found a local hardware store, or picked from old bike parts.  If you are going to purchase the steel I would highly recommend finding a local steel supplier, just search the yellow pages.  If that's not an option for you I would recommend speedymetals.com, they have fair prices and reasonable shipping.  

If your lacking some of the tools I mentioned, find a way to get them.  Borrow them from your uncle, check out yard sales or search craigslist.  These tools are pretty common and should be easy to find for cheap.  For the welder, a MIG is going to be best for this project.  It is completely doable with a stick or even a tig welder so just use what ever you have.  If you have not welded before the 90amp flux core welder I'm using will be easy enough to learn with and at roughly $100 its by far the best bang for your buck.  If you don't know how to weld check the Welding Guide and Learning to Weld from Phil B.

The attached pdf has detail drawings for the frame and the pulling arm, both parts are explained in the next few steps.

Comments

[camping crazy]

This is a sick trailer !! Thanks for posting!

[mykiscool]

You must have some huge legs to be pulling a barbecue and a full size trailer with a steel bike!

[LittleBoyWonder]

dude that is so cool but is it lugit!

[criggie]

Have you considered a safety chain? What about lights?

And depending on your location there may be maximum dimensions for something to be classed as a bicycle.

Whats your top speed compared to the untrailered speed? Half ?

[dbc1218]

Never thought about saftey chains but I think a simple cable bike lock would work well, just connect it between the pulling arm and the rack. I would recommend lights, I used standard blinking bike lights attached to the trailer when I towed the grill.

I didn't check any of the laws around here for limitations, but I never heard of size limits.

When towing your more worried about making sure you don't hit to many pot holes and that the cargo stays on the trailer, than speed. Don't expect to be able to ride very fast. When I towed the grill 10mph felt like a safe speed but I did do 15mph and that felt like the max. Another important thing is your brakes. Make sure their in good working order, front and rear, you will need more space to stop. As far as top speed with out a trailer, I have gone 46mph on a steep down hill in the rocky mountians with the bike in the pictures. thats the fastest I've ever been on a bike.

[bpwmd]

i heard that the axle or the rear trailing arm mounts can tweek the frame. thats why i thought about putting it on the seat post

[bpwmd]

only problem i see is that alot of bike racks have a 20 pound limit. i might modify this to attatch to the seat post.

[dbc1218]

Your right most racks are fairly light duty, but another important thing to consider with this trailer is how and where the cargo is loaded. If you can center the weight of the cargo right in the middle of the trailer, directly above the axles then the weight will be carried by the trailer not the rack.

What you want is to load the trailer with the weight centered just slightly forward of the axles, this will put some down force on the ball which will help it stay attached. Once loaded, but not attached to the bike, the trailer should be tipped forward, then you should be able to lift it by hand with the pulling arm to attach it the the bike.

[tharper]

A lot of the commercial bike trailers attach to the rear axle or some point near there.

[dbc1218]

Yeah I considered mounting the trailer to the axle, like a BOB trailer, but that type of mounting is more complex and I don't think its the best for large/heavy/bulky loads.

[ka1dza]

It's a great project!! I would add holes in the bottom leg so that you could lift it out of the way and slide a bolt through it to keep it there. Also 3/8" plywood would be lighter too. If you are going to keep the tool box ( great idea) on the trailer, you could bolt it down through the bottom.

Again, Great project. The quick release and the ball joint was a great idea in case the bike should tip over.

[dbc1218]

I have considered making some sort of jack, like a screw jack used on most car trailers, to hold deck level when not attached to the bike. I think this would make loading and unloading a lot easier, because the bike is not in the way.

[couchchangeracing]

You could do some simple flip down legs like on the old bikes.

[couchchangeracing]

Looks great. You may inspire me to finish the trailer I have partially built that has been sitting around. I got spoiled when I got my long tail bike. I have one trailer on instructables too.

The only suggestion I have would be to move the pivot ball up a bit from the rack deck. Or get some off set in your trailer tongue. It appears from the picture going over a hump it could bind up on you. I learned the hard way to anticipate these things in my designs (usually after the fact).

Keep up the good work.

[dbc1218]

Your right, I have scratched up the back of the rack because the ball is a to low on the rack. The second nut on the stud was used to make it a little higher but its not enough. I think mounting the ball about 2" above the rack would work pretty well, I have not decided on the best way to do that yet.

[couchchangeracing]

I would suggest cutting the hitch off your tongue and putting the offset there. If you get the pivot too high off the deck of your rack, it may overload the engineering of the rack itself. Your slick adjustable part will more than compensate for the offset. Think 5th wheel trailer in design.

Keep up the good work. I have a box full of failed trailer idea concepts before I settled on the one I built.

http://www.instructables.com/id/Fast-Handling-Bike-Trailer/

[dbc1218]

Good Idea, I didn't think about changing the pulling arm. That may just be what I do.

[neutron7]

I made something similar but it used wheelchair hubs, that way you don't need the outside support?

[l8nite]

great looking trailer ! I think using eyebolts to secure the platform would have given you secure attachment points for securing your load but then they my have occasionally gotten in the way.. thank you for sharing

[dbc1218]

The eye bolts are attached through holes in the front and back sides of the frame and do not obstruct the deck surface. the 1/4" -20 bolts in the pockets hold the deck to the frame not the eye bolts

[l8nite]

I'm sorry, I missed the eye bolts you used, however what I was suggesting was using eye bolts instead of hex headed bolts to attach the deck, killing 2 birds with 1 stone so to speak. I should have looked closer at your design before commenting