So You Want to Build a Cargo Bike...

Over the past few years I’d visit Portland, Oregon researching bicycles and their application to everyday life. I participated in large organized fun rides, rides with friends exploring the many bike trails surrounding PDX and just tooled around town visiting every bike shop along the way. I was struck as to how commonplace cargo bikes are in PDX. Any bike riding family with kids either has a trailer in tow, an Extracycle outfitted with kid seats or a front loading cargo long john. It was inevitable that I would be lured by the design possibilities of cargo bikes and attempt to build one of my own.

On one such visit to PDX I was with my sister enjoying an IPA at one of Portland’s best bike shops, Velo Cult velocult.com. Yes, beer at a bike shop not to mention an espresso bar (they roast their own beans) and performance venue with stage, movie screen and photo booth. I took in the stunning array of a bicycle collector’s passion hung high around the huge space well out of reach. It was clear these were the owner’s personal collection and not for sale. Did I mention, Bicycle Museum?

Displayed by the 12 beer tappers, I noticed a steel can of beer called Churchkey (because that is what you need to open it) and ordered two for the second round. I was attracted by the hue of blue and the golden ochre accent on the face of the can; after a sip, I was struck by the distinctive metal taste. Ahh, the good ol’ days. I commented to my sister that the color scheme on the can would make great colors for a bike. She agreed, but it would be a while before the right bike project of mine would have these colors.

Back home in L.A., I would spend hours researching cargo bike designs online and flipping through DIY photos on tomscargobikes.com. Eventually I worked myself into the “I can do it” frame of mind and started a long journey to building a front loading  cargo bike. 

The following is not a step by step account (there are plenty of websites for that) but rather highlights of my own experience with this project.

There are many things to consider when designing a cargo bike: weight, size, portability, ride-ability, cost, etc. One good thing you can do is test ride several different cargo bikes to get a feel of the ride. You don’t want something that is difficult to balance or behaves too much unlike a normal bike. In any case, it will be heavier and will need sufficient braking power, be slower, and require some getting used to. Many “bakfiets” style cargo bikes like the Bullitt, Cetma and Babboe City have a vertical steering tube to the head set. While test riding a Bullitt, I found this geometry a little quirky when standing up to power pedal up hills. It always felt like I was going to fall over if I didn’t quickly sit back down on the saddle. The steering plane was parallel to the ground like the steering wheel on a bus. My design was going to follow the bike’s original steering plane which, due to the original fork rake, was angled toward me thus giving a more natural feel. Another factor was, I thought limited leg room or knee clearance between the saddle and the cargo box could be a problem when mounting and dismounting the bike. Since I was following the rear bike’s geometry, I made sure I would have plenty of room to manage a heavily loaded bike.

Many of the issues I had with other production cargo bikes were due to the fact that the manufacturers wanted to make their bikes as short as possible and still provide a useable cargo area. So, the rider’s ergonomics had to suffer a bit. I would not compromise ergonomics on my design so, as a consequence, my bike measures 9 ft. from end to end. Sounds huge but I would rather have a slightly longer bike that handles well than a shorter bike where my knees hit the box every time I get on and off.

Since the bike is completely custom, I was able to decide on the size of the cargo bay. But first I had to ask myself, what will I use it for and what cargo will I carry? I didn’t want to make it too small or too large, so I decided to make the cargo area with interchangeable bays for different applications. The wooden box made of Baltic Birch plywood, is big enough for a large cooler, picnic supplies and tools. The cooler cage is lighter but only able to carry the large cooler without strapping it in. And for oversized boxes and odd shaped loads, I plan to make a large flat wooden skid with strap holes around the perimeter.

Tom’s site was a great guide but I knew I would be making a few design changes based on the materials I had on hand.

First I needed a steel framed mountain bike with all the components in working or serviceable condition. MTB’s are good because they tend to be of strong builds and can take the added weight. I found an older KHS in my size at a local thrift store on special for $19. It was well used with some surface rust but intact and would be the rear portion. One big change came when I encountered a girl’s Torker 20” wheeled bike in great shape at my local Goodwill Store. The graceful lines of the single deep oval downtube and meticulous TIG welds meant no reworking of the crosstube to run parallel with the downtube (which never looks right). I saved myself some welding and aggravation. The front wheel looked fresh and true so for 30 bucks, it was worth it. This would be used for the front portion.

Space to store my bikes is scarce. It was imperative that this bike be able to break in-two for easy transport and storage. The coupler was something that I designed and cut from a short end piece of 4”x4” square tube stock with 1/4” wall thickness.

I collected pieces of steel from bed frames for shear webs that are welded between the longeron tubes, and scrap plate stock for stiffeners and braces.

While building this monster I spent more time cutting and test fitting each piece than welding. I have no frame jig, so I made sure everything was lined up on a flat and level surface using a carpenter’s level and a cheap dial angle finder from Harbor Freight. I eyeballed everything down a centerline much like aiming a rifle then tack welded each piece, re-sighting before welding the next piece. This took a long time but paid off with a (relatively) straight bike.

Because I had no bender, the steering rod was made from a series of pre-bent EMT corners, couplers and straight ½” EMT stock. Once I got the length and all the angles correct, I carefully tested it with just the set screws holding it together then zapped each joint with tack welds. I was able to modify certain portions in order to keep the rod from locking upon extreme left or right application of the handlebars.

The steering ratio started at 1:1 then changed to 1:1.5, this being more responsive with less input.

Once the basic frame was welded up, I then spent hours…days grinding my lumpy welds to a fillet shape then welding again to fill voids and adding some much needed braces to areas I thought might require some structural help. Then of course, another round of grinding, welding and grinding again. Once I was satisfied, I mixed up some epoxy filler (West System) and covered all the welds. After it hardened, I sanded and filed until everything felt smooth. Sprayed on some etching primer, sanded that smooth then brushed on my specially mixed blue Rustoleum enamel. Three coats later I prepared my logo stencil for the head badge and applied, again with a brush, the golden ochre accent.

When the bike was done, I took it out for a rigorous 40 mile ride around Los Angeles fully loaded with a large cooler full of ice and cold beer. A real head-turner here in L.A. Everything worked perfectly and it’s a true joy to ride (as long as the beer is cold).

Cheers