Trailer Made: How to Build The Alameda Bike Trailer

I know a thing about bike trailers - maybe two. This was apparently enough to make me an expert in trailers - or at least the sort the Silicon Valley Bicycle Coalition would ask to make a trailer for. 

Let me back up a second.

The Silicon Valley Bicycle Coalition, in addition to making policy recommendations, supporting bike education, leading Bay Area Bike to Work Day (which is May 9 and you need to pledge to ride to work now), fighting for every foot of safe and protected bike lanes in the Bay Area, and engaging the public through creative and interesting rides...also does valet bike parking. 

They have a tent and portable bike racks they bring from place to place so bicycle users have a safe and easy place to keep their bikes. It's really great and I've used it a few times - like at their annual Bike Summit in August and the annual Bike to the Bay event. 

The portable bike racks and tent they use for these are large and hard to move without a car, and a friend said they wanted to use bikes instead and asked if I'd build a couple of trailers.

With excessive certainty, I said I'd be happy to build two bike trailers for them. 

One of the first steps was to figure out exactly what these trailers would be carrying, and that involved going to the SVBC office in San Jose and using a borrowed tape measure. The most cumbersome thing the trailers would be carrying would be the racks and the tent - both about five feet long - so I planned to make the trailers about 5'4" long.

Next, the SVBC put out a call to members for them to donate unwanted bike trailers so I could use them to build what I wanted to build. What I had decided during this period was that I wanted to build two trailers that would be as identical as possible so they'd be easier to build and could share parts if one of them needed maintenance in the future. 

I figured I had the best chance of getting two identical trailers if I didn't solely rely on SVBC members to bring me theirs, so while I was waiting for I engaged in my own efforts to acquire trailers, and I was able to find this at Good Karma Bikes: 

This is a used Burley child carrier - and a pretty nice one at that. The price was quite low as the seatbelts looked as though they had been torn apart by an unruly family of wolverines. 

Another friend of mine had a trailer she didn't use that was pretty much brand new. When I asked her how much wanted for it she replied that she'd part with it for ramen. I told her she had a deal, and after treating her to lunch at Kumako Ramen in Japantown I ended up with this.

This is a Burley cargo trailer and the only thing it seemed to share with the one I purchased at Good Karma Bikes was the trailer hitch - which was one I hadn't seen before (ignore the thing in the middle of the photo - I'll get to that in a minute).

As most of you know I welded a universal trailer hitch onto my City Bike a couple of years ago - and this trailer took neither. It did, however, come with a coupler that can be attached to a rear axle. So I left the trailer under my desk at work, attached the hitch to my bike at home that night, and towed it all the way home the following evening (I also made, from a piece of 1" square tubing seen in the middle of the above photo, a hitch I could weld to the City Bike but I abandoned the idea since it didn't seem strong enough to support the weight).


A few days passed before I was told a few trailers were available at the SVBC. I picked them up and brought them home on a day I had my car. 

Things weren't looking promising. I had four trailers, all with different styles and built with different methods and materials. I was worried I wouldn't be able to build two identical ones like I wanted. 

But then, my friend at SVBC said there was yet another trailer available in San Mateo. When she described said trailer it sounded like it could be worthwhile. It found its way to the SVBC office, and it was a match to one of the others.

Both of these are an older style of Burley I'm quite familiar with. In fact, I built a bike mover for the Domus bike drive and used it to carry shopping carts using an old Burley trailer.

This was also the design I was hoping to find since these trailers use 20" wheels on a normal hub. Even though the spokes are usually offset, 20" wheels can be found anywhere. The last thing I wanted to do was build trailers that took special parts - like the Burley pop-on wheels. They're very cool, but I'd rather an SVBC volunteer pop in and out of Good Karma Bikes for a minute and a half to replace a 20" wheel than have a trailer out of commission for days while ordering a more expensive pop-on wheel. 

The trailer directly ahead of me and the one to my immediate right would be the main platforms for the project. I did swipe out the tires from the fancy blue Burley trailer with the ones on the red and yellow one since I wanted the SVBC trailers to have the newest tires. I added Tuffy tire liners* to both so the trailers would be less likely to get a flat to begin with.

I went to work on the cloth sides like Errol Flynn knifing his way down a ship's sail**. I noticed the frames were just about identical but the mounting points for the tongue were plastic and would get in the way for what I had in mind.

My idea was to use simple, aluminum frames bolted on top of the existing trailer frame with a 1/4" PVC floor. Based on what the SVBC had told me, the cargo the trailers were expected to carry could ride on the PVC easily without too much worry that they would break. They'd also be light and wouldn't swell and shrink when exposed to water. Wood would have been cheaper but it would absolutely have been heavier and would not last nearly as long. 

A trip to Lowe's netted most of the material I needed that wasn't lying around the shop. I also made subsequent trips to ACE Hardware on The Alameda (one of which was to discover the bike racks were being installed out front).

I did manage to get all of the materials to my shop on brand.

I toyed with the idea of trying to learn, once again, how to weld aluminum (a task I had tried and failed in spectacular fashion in the weeks after getting a Lincoln Electric spool gun as a self-given birthday gift years ago). But I ruled that out soon too. Not only was I squeamish about allowing SVBC volunteers towing the trailers to be the test subjects for my aluminum-welding skills, but I reasoned the construction of the trailers should use hardware that could be easily found and have the ability to be fixed with tools that would be readily available. 

After measuring the width of the trailer and making 45 degree angle cuts, mount the frame to heavy-duty corner braces with 1/4 bolts and lock nuts. Not pictured are the two bolts that will come in through the bottom of the brace. (view of the upper right corner of the trailer)

Measuring the inside of the Burley trailer gave me something along the lines of 22". When the large, 5'4" aluminum frames I was making would be mounted on them, I knew I'd have to extend the tongue of the trailer to account for the longer cargo bed. I intended to buy a tube long enough that was the same thickness, bend it with a pipe bender, and use the existing hardware. 

It was at this point I ran into a problem: finding an aluminum tube that thick wasn't easy. I made a lot of phone calls to some of the random industrial-looking buildings clustered around Monterey Road in San Jose but got nowhere. I even rang a place (recommended by another place) and the person who picked up the phone greeted me gruffly with the words "This is Eddie."

My heart leapt when I heard that, because I was sure that Eddie would be the one to help me. But alas, Eddie didn't come through.

Not having a long enough trailer tongue meant I'd have to modify the design. Moving the existing tongue forward 15 inches meant having a completely new mounting system since the plastic brackets - which I had mentioned earlier - couldn't be moved. 

With the rectangle of aluminum is centered over the Burley frame I removed the mounts for the wheels, clamped everything together, and drilled clear through before putting the mounts back on (using longer bolts to accommodate the frame) The steel rectangular bars with the half-moon cutouts are components of Box Bike by DIYBIKING.COM and were used only as spacers for this build. 

This took longer than I thought to figure out - and most of my thought process involved cutting and moving pieces of aluminum around while season 2 of 'Justified' played in the background. 

By the time season 2 spilled over to season 3,  I landed on the idea of cutting L-shaped pieces of aluminum brackets and using two bolts each to mount them to two pieces of 1" square tubing that would span a couple of inches wider than the inside width of the frame. To assemble two trailers, I was only short about 4' of square tubing so the other night I set off to Lowe's to buy what I needed.

Instead, I came back like this.

I miss Orchard Supply Hardware - a local hardware store chain that was founded in the early 1930s and eventually bought by Lowe's before being unceremoniously dissolved in 2018. Since then, I've resigned myself to the fact there are only two sizes of aluminum ever available: a unit that is half the size of the aluminum I need, and another that is twice the amount of aluminum that I need. Lucky for me, I always carry reusable wire ties and these marvelous things called Gear Ties.

With the square tubes of aluminum in hand, I sawed them carefully to the width of the trailer, used an angle grinder on the ends to smooth out the sharp spots, and set them on the frame about five inches apart to mimic the approximate placement of the mounting points on the existing trailer. That done, I sawed up four pieces of a 1" L-bracket, ground off the sharp bits, and set them in place. 

During this time I found that owning several pairs of vice grips is a wonderful thing. What I would do was clamp the two pieces of aluminum in place so I could make 1/4" holes with a cordless drill. Since I was using 1/4" bolts throughout I had to be careful not to drill too close to one another or to one side of the L-brackets.

In order to mimic the original mount as much as possible, I spaced them out on the underside of the frame the same distance apart as they are on the unmodified trailer. I also bought a bolt the same thickness and used clovis pins so one could easily swing the tongue out of the way for storing the trailer. For the sake of paranoia I added anther piece of aluminum as a brace between the square tube and the L-bracket frame. 

Before cutting and attaching the 1/4" foam PVC floors, I wanted to add some strength to the center of the trailer. As it happened, I had some aluminum tubing and found a lock nut could fit inside if I put in a bolt and dropped it repeatedly on the workshop floor to drive the nut deeper into the tube. I kept removing the bolt and looking inside to monitor my progress.

I'm positive there's a more elegant and sophisticated solution than this, but you build what you can with the knowledge and materials you have.  

Done on both sides, I carefully drilled through the Burley frames so I could thread a bolt through the openings and into the nuts that were now lodged in the frame. You can see the rod in the middle of the frame in this photo.

The PVC was easy - because of my failed cargo bike business (more on that another day, I promise) I had a big, yellow piece of 1/4" foam PVC standing in the corner of my shop that was 2' by 6'. A visit to Tap Plastics on The Alameda gave me some 1/4" foam white PVC at a reasonable price (they even cut it at the location so I could carry it easily). 

For the floors all I did was place the PVC on the table, set the upside-down trailer frames over them, and trace around them with a sharpie. That accomplished, I took to sawing them with a jigsaw.

I think I've told you before: those collapsible table-things that are used at tradeshows? They are fabulous workbenches whenever you need to saw anything large. The sawblade passes right through and the piece you're cutting off won't fall to the floor. Then when you're done you just collapse it and put it on a shelf. 

With the foam PVC in place, I used more 1/4" bolts and locknuts to fasten the PVC to the frames - spacing them out about every 8" or so. When I was done, I added some reflective stickers - white in the front and red on the sides and back so they'd be more visible if the SVBC volunteers would be towing them at night. 

When I did a test ride carrying a few random items I noticed the items would slide, so I found a couple of old yoga mats and cut them to shape. I also added a couple of mounting points to the corners for bungees and used an angle grinder to take off the ends of the bolts. 

Finally, it was time for the testing. I grabbed the biggest and heaviest things from my shelf, lashed them down, and set off. 

That's pretty much all testing consisted of, really. I also rolled the trailer off of curbs to make sure nothing particularly awful would happen. 

I ended up naming the design "The Alameda Bike Trailer" because everything you need to build one is available along a short stretch of The Alameda in San Jose: from Ace Hardware to Tap Plastics (even to La Dolce Velo, if you wanted to buy trailers to use as bases there). With a few parts and a few local shops anything is possible. 

And there you have it. Other than 1/4" bolts 1" in length with lock nuts, 1/4" foam PVC, 1" square tubes, 1" flat angle pieces 1/8" thick, four 2" zinc-plated corner braces, reflective tape and probably any kind of trailer and you can make The Alameda Bike Trailer. As you can see I'm not really into posting detailed instructions - this post is more like one of my grandmother's recipes, where "smidgekin" is a unit of measure but it's up to you to determine what that means. The point is, build on. And if you're in the Bay Area please remember: Bay Area Bike to Work Day is May 9th so be sure to pledge to ride on the SVBC site.  

Also: there is an affordable housing-themed bike ride in San Jose on May 11th I'd like you to ride in. I've talked about the problem of traffic and housing as the same problem before and this explores bikes and affordable housing as the same solution. It'll be worthwhile and I hope you can come. Thanks for reading and thanks for riding. 

*after the debacle in Manchester that had a embedded piece of glass give me several flats, I installed tire liners and haven't had a flat on the Bike Friday in almost two years.  

**or Sloth and Chunk sliding down One-Eyed Willy's pirate ship in 'The Goonies' - whichever you prefer.