Building a better portable bike rack
This summer I ended up in the middle of the desert with about a hundred thousand other people. I was fortunate to join a camp filled with an amazing group of people. My contribution was to provide parking for the nearly 150 bicycles expected to show up throughout the week.
Originally I planned to spend a week on the project, but it turned into almost 4 months of research, iterations, and experiments. The criteria for a great bike rack at the burn (in my humble opinion) should be:
- Inexpensive to build
- Fast and extremely simple to setup and take down
- Little to no construction waste
- Use as little storage space as possible
- Accommodate as many bikes sizes/styles as possible
- Require no specialty tools to construct
- Use only universally available materials
- Robust and reusable for at least several years
That's a pretty big wish-list, but what's the fun if there's no challenge?
TLDR:
Burning Man Designs
Of course, rule #1 as a designer and engineer is "don't reinvent the wheel" so I set off to find an existing design to build. Burning Man is such a nexus of incredible creativity and expression I thought I'd have trouble narrowing down to pick a design. Instead, I was shocked by how little innovation has spread for this staple building product.
Part of this is for good reason. The rack used overwhelmingly at burning man, the conduit cage, has a lot going for it.
The conduit cage
First and foremost, the instructions are posted as part of the theme camp guide from the official site requiring little to no investigation. But the design does have a lot going for it:
- It mimics the most common commercial metal bike racks used in cities. People instantly recognize what it is and how to use it properly.
- All the materials are available at any building supply store.
- It is extremely cost-effective fitting 18 bikes per rack at a cost of ~$45.
- Requires no specialty tools to build and is relatively easy to transport and assemble on site, as well as to break down when leaving.
But it also has some downsides. It takes a lot of labor to build - typically a couple of hours per rack. It glue and screws and multiple types of wood. It doesn't pack away very well. And it's a bit, well, ugly.
Playatech Bike Jack
The Playtech bike jack is in some ways a big improvement.
- Its designed to be cut from a single sheet of plywood and work without fasteners or glue.
- Because of the material, storage and transport are much easier and more efficient.
- It looks pretty cool :)
But all is not perfect here either. It costs 3x more than the conduit cage, it has about 1/2 the efficiency, there are a lot of pieces to put it together, and it can put undue stress on the spokes of bike wheels - otherwise known as "rim twister" or "spoke stretcher" (read "the ugly" here). These racks are almost never found commercially because of the damage they can do to the wheels.
The Pole rack
By far the easiest to build and the cheapest, this style of rack comes from triathlons.
It requires each rider to lift the seat over the cross-bar to secure the bike to work. If your bike has anything obstructing this, it can be pretty difficult. I figured that between the heat, alcohol and other substances at the burn, not many folks would even understand how to use it, much less be willing to put forth the effort. (footnote, I was correct. Only a few camps used them and almost no one properly stored their bikes on this style of rack).
Also, burner bikes tend to be heavy, and be carrying other items, making the lift a lot more work and making it easy to overload the rack. (Per The Triathlon Bike Rack you can only load 6 mountain/hybrid/cruiser bikes on a 104" short span, and after lights, bins, playa dust and ornaments, that would be closer to 4 burner bikes. Less than 1/4 the density of other common racks.
Circular Racks
A completely different take, with pretty good instructions on Instructables has a lot going for it as well.
Simple to make and assemble, very robust and it offers a lot of density. The price is hard to beat as well. Wire spools can be found in abundance, usually for free, bringing the cost per rack to about $10 for 2x4's and dowels.
But it doesn't pack or disassemble easily and it can be challenging to use a circular layout for parking over a hundred bikes in an orderly manner.
Found object racks
There are lots of smaller camps who make pretty ingenious racks from scrap goods - Futon frames, Shipping palettes, PVC pipe and more.
These are perfect for small camps, but unfortunately not really a viable design for larger camps that need an easy to assemble and transport solution. If you can't locate the materials for free, the cost to make more can get big in a hurry.
Looking outside of the Burning Man community
I found literally hundreds of incredible designs for bike racks in the wild. However while many were absolutely beautiful and most very functional, there was very little I could adapt to meet the criteria I set out for myself. Most commercial offerings are made of metal, typical tube or square stock steel. They are also nearly always designed to be permanently installed in a location. This tends to mean they are heavy and extremely space intensive to transport.
I did find a bunch of interesting ideas, particularly when searching for wooden bike racks
I really liked the simplicity of this one
But then I found the inspiration for my own design. A pretty awesome company out of Australia - Bikerax, makes a line of fold-flat, plywood bike racks that are beautiful, well designed, and very robust.
Simple to assemble and very tough. Their design doesn't make the most efficient use of material, but I could immediately see the opportunities to improve upon it. So I used the BikeRax as my starting point.
Designing a better solution
I learned a few lessons researching existing racks.
- Three points of contact with the tires.
- Avoid resting on the spokes of the wheels.
- Enough space to hold the tire in place, but not too much so that the wheel doesn't stay straight.
- Enough space between each bike for the handlebars.
I also learned about bike tires and wheels. There are 4 "common" diameters - 29", 26.5", 26" and 24". 29" wheels are most common for road bikes, with 26" being the standard for most mountain bikes, hybrids and cruisers. 24" is most common in BMX and kids bikes.
There's also the consideration for tire width. Most road bikes have a 1-1.25" wide tread, with mountain and hybrids commonly having 2.5-3" treads. "Fat bikes" range from 3.8-5.5" in width.
Based on looking at a lot of photos of parked bikes from burning man, the vast majority of people are using bikes with 26" wheels and 2.5-3" tires. Even so, I wanted to support as many bikes as I could.
This is my first set of explorations on different ways to hold bikes. Obvious inspiration came from BikeRax and their 30 degree angled slots. I found that by making the taller piece vertical, I could mirror the rack, enabling bikes to park on both sides similar to the common conduit rack. This doubled the density with little additional material. As you can see in the image above, this design also fits 24-29" wheels well.
But I also needed to consider tire width and handlebar width for spacing of the bikes. I found that most bikes have handlebars between 16 and 19" wide. So I wanted to ensure that there would be enough space for riders to park next to each other. But I needed to balance this with two other needs: part nesting and tire width. You can see the dilemma in the design:
From my data, it looked like these bikes represented about 5% of the bikes at the burn, so one spot per rack should be plenty to accommodate these riders.
You can see the challenge though. The wider I make the space between each wheel, the less efficient use of the material. If I make the wheel gaps wider, it will be harder to park a bike without it wanting to tip and rack the wheel. I opted to add a slot for a single "fat" tire per rack. This is complicated even more when you nest the parts:
Nesting the parts serves two purposes: reducing waste material and making the racks extremely space efficient for storage.
The next piece of the puzzle is the cross-section. It needs to be sturdy but still maximize space on a 4x8 foot sheet of plywood. I went through dozens of iterations on these, finally settling on a partially nested design:
With this design, a single sheet of 3/4" plywood will park 22 bikes at a cost of ~$32 for Pine plywood.
This design and layout also have less than 4% board waste, and including cut waste is still 85% efficient. It is intended to be cut on a CNC Router but can also be cut out by hand with a standard jigsaw. We ended up cutting out most of our racks on site with a jigsaw and it worked really well. It takes one person with an electric jigsaw about 45 minutes per board to cut out and assembly two racks.
The final result
After months of work, and with the aid of a recently purchased PrintrBot Crawlbot I was finally ready to go. We cut two on the CNC and another 6 with jigsaws.
Even better, none were damaged at all, and we were able to break them down for storage in less than 10 minutes:
(You'll note we got a little creative with 2x4's having run out of material on site, but they worked almost as well!)
In my time at Burning Man, I felt like I took so much and gave back so little. I hope providing this to the community will be the start of a lot of giving to come :)
You can find the plans free of charge under a Creative Commons license here on Thingiverse. I've provided plans for a number of different configurations depending on your needs. Feel free to use them, remix, improve and share. If you are so inclined, I do accept donations the "Tip Designer" button on Thingiverse :)
