Introduction: Bike Trailer -- Tough and Light

Picture of Bike Trailer -- Tough and Light

Instructions on how to build a tough and light bicycle trailer out of standard light gauge angle iron found at the hardware store. This design is tough, relatively light, easy to build and easy to customize.

Step 1: Collect Tools

Picture of Collect Tools

Tools required for this job include --

Hack saw
Adjustable wrench (two)
Ratchet with 5/16 socket
Drill with phillips bit
Tape measure
Combination square

If you have a circular saw, it may be easier than using the hammer and chisel. Eventually I got sick of using the hack saw and borrowed a friend's angle grinder with a cutting disk.

Step 2: Collect Materials

Picture of Collect Materials

These photos are just to show you what the materials look like. Below is a more or less thorough bill of materials. Costs maybe $100, but well worth it as a cargo trailer at a bike shop is about $300.

6 each conduit straps, two-hole kind, sized for 1/2 inch conduit
About 19 linear feet light gauge angle stock (find at hardware store or local big box store)
4 washers, 1/2 inside diameter
38 washers, 5/16 inside diameter
8 wood screws, 1 inch long
8 bumper washers that fit the wood screws
24 bolts, 5/16 diameter by 3/4 inch long, hex head
2 bolts, 5/16 diameter by 1 1/2 inch long, hex head
24 nuts, 5/16
24 washers, split ring, to fit 5/16 bolts
3 foot 1/2 inch threaded rod
2 each 20 inch diameter wheels, plastic spokes
3 feet 1x3 nominal lumber
2 feet 2x6 nominal lumber
6 each nylon washer, 1/2 inside diameter, about 1/2 inch deep
12 feet rope, about 1/4 inch diameter
4 machine screws, no. 10 diameter by 1 1/2 inch long, phillips head
4 nuts, no. 10, with nylon locking inserts
1 caster wheel with removable wheel and ball bearings at its base
1 1/4 bolt with pin, to be used as a quick release between tongue and receiver

Step 3: Cut and Assemble Chassis Frame

Picture of Cut and Assemble Chassis Frame

The basic chassis frame consists of a 2 foot by 3 foot rectangle of angle iron, reinforced with two 2 foot long pieces in the center.

Cut 2 each 3 foot pieces and 4 each 2 foot pieces of the angle iron. Bolt together using the 5/16 hex bolts with 1 split ring and 1 cut washer each. The frame will have some weakness in twisting, but we'll make it more rigid in the next steps.

Step 4: Assemble the Axle

Picture of Assemble the Axle

The axle, axle support, and straps are attached to the chassis frame in one giant step.

Cut the 1x3 to about 26 inches long and position in the middle of the chassis frame. There should be about a 1 inch overhang on each side.

Bolt the 1x3 to the frame with a 1 1/2 inch long 5/16 hex bolt. I used a cut washer and a nut with nylon insert, since this is a crucial connection. You'll have to counter sink the hex head so that it doesn't interfere with the axle.

Before attaching the axle, spin a 1/2 inch nut onto the threaded rod first, then two nylon washers (bushings). Spin two more nuts onto the threaded rod and position next to the conduit straps as shown.

Pre-drill through the wood and angle iron and bolt the conduit straps onto the chassis frame.

Step 5: Construct Center Support

Picture of Construct Center Support

Cut the 2x6 nominal lumber to 24 inches long. The piece should fit snugly between the two intermediate angle supports, directly over the 1x3.

Notch out the ends of the 2x6 to accommodate the bolts that are securing the axle assembly. You can use a hammer and chisel and cut away wood until if fits, basically trial and error. I actually used a circular saw and curf-cut the end and bashed out the loose bits.

Secure the 2x6 into place using wood screws and bumper washers. Use four screws each side, two in the ends and two on the bottom. Be careful here, I split the first 2x6 doing this, so I recommend pre-drilling and not torquing it down a lot.

After the 2x6 is secured, the frame becomes much more rigid without any twisting action. The 2x6 also supports the cargo and resists bending of the axle under heavy load.

Step 6: Assemble the Tongue

Picture of Assemble the Tongue

Cut a length of angle iron to 31 inches long. At about 19 inches down, cut a vee notch to allow the piece to bend about 40 to 45 degrees. The short end of this piece becomes the connection to the read axle on your bicycle, so you need to check the length of your bicycle wheel first. The dimensions here are probably fine for most mountain bikes, since that's what I tow the trailer with.

Once your satisfied with the length and bend angle, cut two pieces of angle iron to reinforce the tongue. The lower one is about 10 1/2 inches and upper one is about 12 inches. Bolt these to the tongue to form a C in section.

Cut two more piece of angle iron, each 7 1/2 inches long. Bolt these to reinforce the bend in the tongue.

Fashion a clip that will reinforce the connection between the tongue and chassis frame. Its made from three pieces, two 2 1/4 inches long and one 1 1/2 inches long. They all bolt together with one bolt, then bolt them to the tongue and frame.

In early models of this trailer, the weakest part was the tongue, which flexed so much during riding that it permanently bent and twisted and caused the trailer to sit crooked. So if there seems like a lot of reinforcing on the tongue, it for good reason.

Step 7: Build the Receiver

Picture of Build the Receiver

Remove the rubber wheel from the caster wheel.

Cut a length of angle iron about 4 inches long. Grind or cut down one edge so that its no more than 3/4 inches. Grind or cut the corners of the short leg as well.

Bolt the caster wheel to the angle iron in such as way that will allow you to skewer the angle iron with the wheel axle skewer and tighten down.

Step 8: Build and Attach Coupler

Picture of Build and Attach Coupler

Cut two lengths of angle iron to 3 1/2 inches. Chop or grind down one edge of each piece so that there's no more than 3/4 inch left of the leg.

Nest these two pieces together and bolt to the end of the tongue. Jam cut washers between tongue and coupler so that the coupler fits inside the caster wheel receiver, but not tightly, as a little play is good here. This should take about 14 cut washers total, but it depends on the side of your caster wheel and washers.

Step 9: Install Wheels

Picture of Install Wheels

Wheel installation is easy, just follow the order in the photo.

You could put some thread lock on the outside nut, but with the end cap, its probably not going to work itself off, especially if you tighten it down to the other nut.

Before putting on the end cap, cut the end off the threaded rod leaving about a 1/2 inch extension beyond the outside nut. The cap will cover this.

Don't tighten the nuts onto the washer because it binds up the bearing and the wheel doesn't rotate smoothly. Instead make it snug and tighten the bolts to each other.

Step 10: Thread Cargo Net

Picture of Thread Cargo Net

Thread a rope across the chassis frame with 1/4 nylon rope to form a net to hold cargo. This can be done in any kind of creative pattern, shown here is basic chain link pattern.

Step 11: Final Trailer

Picture of Final Trailer

This is how the trailer looks completed. I can carry at least 100 pounds of cargo on this with no problem. At only 20 pounds, this is also pretty light weight for its class. You could really pimp it out with reflectors, a good paint job and a flashy rope net.


fractionalphysicist (author)2009-07-15

One problem with this design that should be fairly easy to rectify. there isn't a rotational degree of freedom about the in-plane axis; i.e. you cannot lean your bike in a turn, as required for any substantial amount of momentum. Other than that a great build. Just be careful around those bends.

Yes, that is a problem I'm aware of. There's been enough play in the coupler/receive for this not to be a big problem. However, I haven't had to pedal "out of the saddle" yet with the trailer (for going over hill or sprinting). I'm interested in anyone's solution, though I prefer not to have to completely redesign the connection yet again.

Icetrike (author)arcraven2017-02-07

Look at the connections for Off Rod trailers that people use behind 4x4 motors..
thats the way to can go left to right...up and down and 360degrees...and they are very strong...thats what we want.

Msaggese (author)arcraven2009-07-15

What about a hinge type of setup between the caster and the bike? The hinge would be at a right angle when the bike is upright, with the caster below it, so that in a turn the hinge could go up or down depending on the direction of the lean. I'm sure someone would be able to figure it out

arcraven (author)Msaggese2009-07-15

Good idea -- sketch attached, comments welcome. (no, I do not work for Perkins + Will) I'm wondering if there will be too much back and forth movement in such a design.

Dr.Bill (author)arcraven2011-11-19

This is a good idea for turning with a lean.

You might catch the spokes in the rear wheel. What about another caster in line with the support arm and 90 degrees "out" from the 1st caster.

I was thinking more along the lines of the hinge being horizontal, or bent at a 90 degree angle, so that when leaning the bike right, the hinge will open downward, and when leaning left, it would close upward. This might avoid the problem of the spokes catching, but i'm not entirely sure. i'm just thinking conceptually

Msaggese (author)arcraven2009-07-15

Exactly, That was the only problem that i could see with it. It might work

thepelton (author)Msaggese2009-07-15

I was about to suggest some sort of universal joint near the point of attachment to the bike, myself. If you just have it attached with a bolt, the tires would drag and screech on a sharp turn, and wear out too fast.

kklaw (author)arcraven2009-07-22

How about a heavy duty spring? The connection on my store-bought trailer that our kid sits in has a simple rigid post-and-hole connection but a section of the tow bar is actually a heavy spring. It makes turning quite easy and provides much needed flexibility between bike and trailer. Just a thought.

What I did when I needed a light-duty universal joint was to take two fairly heavy threaded eye-bolts, get one red-hot with a torch so I could open it up and put the opened end through the other eye and closed it up again. Worked just fine.

miguelbarroso made it! (author)2015-01-23

Hi, inspired by your project, I've buitl a similar one. Changed some things: no wood parts (the axle goes through the metal profiles, locked down with nuts and spacers, reinforced in the center, a bit longer (1m), and the trailer tongue is centered, because I have an Xtracycle. Here are some pics. It's very sturdy, I can stand on it and jump! and it doesn't nudge

Icetrike (author)miguelbarroso2017-02-07

This is a very good idea...I hate side mounts...they break..sooner or later..mine broke three times on a 15 000 trip...the center mount is the way to go...I work on a center mount trailer at the moment that I want to use when I tackle the Pan American high way later this year...

arcraven (author)miguelbarroso2015-01-25

This is awesome! The way you've constructed the tongue gives it rigidity, so no need for cables and such. Very clean work, you've mastered the steel angle material! Also like your hitch solution.

miguelbarroso (author)arcraven2016-09-21

I still haven't published here in Instructables, but you can check a lot of pictures and also the design process in here: (in Portuguese, but Google translate gives a reasonable result).

miguelbarroso (author)arcraven2015-01-25

thanks. the hitch is not my idea:

ROBERTC199 (author)2016-01-18

My bicycle trailer hops from side to side and I have to ether slow down or stop, it only happens when I go fast, is the trailer to light? Do have any idea why it hops from side to side???

MihailD6 (author)ROBERTC1992016-10-25

Might be because the axel of the trailer is on the middle of the length. It has to be 60% more to the thonghue. I guess

MTJimL (author)2015-03-10

Nice build, and a great starting point for the trailer I need. Thanks.

arcraven (author)MTJimL2015-03-20

Great, happy that it helped you!

juiceman74 (author)2012-07-15


Did anybody try using such a trailer for hitching kids on it. .

How Safe is it compared to commercialized products? I'm offriad of of rolling over in high speed turns.

What about a canopy and seats I didn't see any instrucatables that includes those.

What about road bumps resistance, how much of a bumpy ride is it on a white dirt road?

10x, all.

arcraven (author)juiceman742012-07-25

I've not trailered any kids on mine.

Dr.Bill (author)2011-11-19

Can You Say Erector Set ?

I wonder if this can be put into a box and marketed . . . . . .

parrster (author)2011-11-19

Brilliant. I've been looking to build something like this for my son to help with his paper run. I like this design for its simplicity and ease of construction. Great job.

Databanks (author)2011-07-19

Wow, such a cheap but effective way to make a coupler. And I've no shortage of castors that have worn out their rubber wheel hanging around...
Nice idea and thanks for sharing

rabid_engineer (author)2009-07-16

Most interesting! Congratulations on a sturdy and (in its neatness) visually appealing design. I wonder, have you put it to extended use yet? I suppose not, looking at the date of publication. The reason for my asking is that I think nylon washers as bushings might wear out quickly, since it is a threaded rod. Perhaps a flush one would have been better, but then, you have the trouble of holding the axle and wheels in place, of course.

arcraven (author)rabid_engineer2009-07-17

Good point. A friend recommended filling the threads with "liquid metal" (never heard of it before) and filing it smooth so that the axle doesn't wear down at those points where it touches other parts.

Nate Cougill (author)arcraven2010-02-26

Your friend is probably talking about JB Weld. It's available at most auto-repair shops like Autozone. Great project!

Baronrc (author)2009-11-30


this is beautifull, rabid_engineer said it perfectly, "in it's neatness visually appealing"

I really wish I hadn't sold my bike, if I still had it I would go out and do this!

godspiral (author)2009-10-02

where/what are the wheels from?

arcraven (author)godspiral2009-10-05

I bought the wheels from Northern Tool. They're about 20" diameter and have built in bearings. Here's Northern Tool website --

weblar (author)2009-09-24

I like your trailer design a lot - it does look strong and light!!

I agree with the posts regarding the "swivel-ability" of your attachment point. I've designed and built a number of bike trailers over the years, and have accomplished that "swivel-ability" by moving the attachment point for the trailer to just behind the rear wheel/tire of the bicycle using 3/4 X 3/4 square steel tubing that is also available from hardware stores and then using a second caster to allow the full range of trailer tongue motion: up and down, side to side, and rotational.

Though the current trailer I designed makes use of a push/pull golf cart that I purchased off CraigsList for the low price of $5 and a plastic tub, the trailer attachment design I suggest has held up very well all this summer over some very extended bicycle rides (one over 225 miles).

I also replaced the cheap bearingless wheels that came on the golf cart with sleeve-bearing wheels that I bought from Northern Tools - a great place to shop for wheels for projects like these.

You can see the trailer coupler I describe also posted on Instructables at

macrumpton (author)2009-07-17

Do you think rather than cut out a notch out of the tongue if you did a single cut and bent one side up and the other down you could overlap them so you could put a bolt through both sides?

arcraven (author)macrumpton2009-07-20

Yes, I did try this when building. The angle iron is light gauge, but not light enough to do that easily (although if you cut it craftily enough, I'm sure its possible). It was easier for me to cut the notch and reinforce it with the bracing.

rowerwet (author)2009-07-16

why not use a second caster to make the second hinge axis, connect them at the axle bolt holes (one axle bolt through all 4 axle hole ears) so that one swivel plate was 90 degrees to the other. (one for pitch and one for roll) would make the tounge connection a little different, but no major changes. great design!

ericdncn67 (author)rowerwet2009-07-19

turning with the second attachment would stress the rear of the bike.

rowerwet (author)ericdncn672009-07-19

the axle bolt would be the joint for bike CL to trailer CL angle changes, the swivel plate attached to the frame would be the joint for bike to trailer pitch changes, and the swivel plate attached to the trailer arm would be the joint for the bike banking into turns while the trailer stayed flat.

arcraven (author)rowerwet2009-07-20

I'm experimenting with this right now and will post my pics/opinions. At first glance, seems it could work.

arcraven (author)rowerwet2009-07-17

Seriously considering doing this. Thanks.

macrumpton (author)2009-07-17

Instead of mounting the piece of wood on the frame to mount the axle on wouldn't it be easier to just drill two axle size holes in the angle iron and mount the axle directly on the frame? Then you could eliminate the wood, brackets and mounting screws. It would even lower the center of gravity a couple of inches.

ericdncn67 (author)macrumpton2009-07-19

light angle isn't strong enough for the 100lb limit. The wood in the middle of the platform gives it strength(making up for light angle).

arcraven (author)ericdncn672009-07-20

Exactly. Without the 2x6, the axle bends under heavy load, causing the wheels to splay out. The wood also adds rigidity to the frame so it doesn't rack.

brizzx32 (author)2009-07-17

Hello good Instructable, just had a question did you just use a regular bike wheel or what kind did you use and where did you get it?

arcraven (author)brizzx322009-07-20

The tires are for garden carts. I bought them at Northern Tool. Here's the link --

goodgnus (author)2009-07-15

Reminds me of an erector set! Any bike trailer is a good bike trailer as far as I'm concerned. Props!

Iconoclastic Technocrat (author)2009-07-14

Very nice instructable! Nice attention to detail. I like the way you made the angle on the trailer tongue with L stock metal. It's hard to find recycled round tube with the angle you need. The name of the pin you mentioned you forgot is a clevis pin. I also like the use of that type of wheel -do you have a link for your source?

Thanks! I used Northern Tool to source the wheels. Links to home site and to 20 inch wheel.

Yerboogieman (author)2009-07-14

Those "Adjustable Wrenches" are called Crescent wrenches.

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