Sunday, April 3, 2011

Molly's Hitch= Hitch for vertical dropout with close clearance

Machined from a block of 6061 Aluminum.
Molly's rig on the way to a gig.

Designed to fit on a bicycle with vertical dropouts and close clearance in the dropout area.

Lindsey's rig

Adam Kobetich's trailer

Sunday, February 27, 2011

Heavy Duty Coffee Cart

This trailer will be the frame for Good Bike's coffee vending cart.
The bed is 36"x 48" (3ft x 4ft) and the total width is 46" (3 ft 10 in).

The hitch arm is made from 1" round steel tube with a wall thickness of about 1/8". I made the bend with a JD^2 model 3 bender. The arm sleeves into a bigger beefy steel tube that has an ID of about 1" and wall thickness of about 3/16". Really beefy, as far as bike trailers are concerned. As the photo below indicates, it is held on by 3/8" bolts. These will be replaced by 3/8" lock pins to make hitch mounting/ dismounting quick and tool free.

You may be wondering what the heck those things are at the corners. They look like table legs. That is indeed the purpose they serve. The idea was to have a bike trailer turn into a vending cart with minimal time and effort. The feet drop down at all corners to hold up the cart, then the bike can be disconnected and the hitch arm removed.

Here is a front view of the trailer and it's feet holding me up.

Detail of a leg assembly. The legs are 3/4" round tube with some 1/8" flat stock welded at one end. The leg collar has some notable details. It is 1" round tube with 1/16" wall, it has 1/4" nuts brazed to it, and it is tig-welded to a 3/4" square tube that sleeves 6" into the open end of the trailer frame.

Friday, February 4, 2011

rambling manifesto: Junk Strategy for a Critical Energy Philosophy

Trailer for double bass made from salvaged junk

I have been focused most recently on making things out of new material; this is both good and bad. I am now returning to the idea of making things out of 'junk'.

There is a time and place for new materials that are specifically designed for a certain purpose. There is also a time and place for re-purposing raw materials that have been salvaged from the junk pile.

Using items for applications other than their original purpose can be sketchy, but there is an art and science to it. Just because something was designed to do one thing, doesn't mean that it isn't capable of doing another. In the spirit of direct reuse of materials to save energy and resources, I am obligated to reuse materials when appropriate.

It is easy to think of bicycles as really 'green'--environmentally friendly, sustainable, etc. But behind every new product there is a chain of production that is probably not sustainable. Bicycles are made in factories from raw materials just like anything else. They get shipped across the world in boxes full of disposable plastic. Look in the dumpster of a bike shop and you'll see the mountain of plastic that results from the shipping of bicycles. The end result is a machine that efficiently and cleanly transforms human energy into motion. Thus we title it "green".

But "green" is a relative term. Compared to cars, bikes are green, because they use much less energy and don't pollute like cars do. Well, compared to jumbo-jets, cars must be green, because they use much less energy and don't pollute like planes do. And compared to walking, bikes are bad for the environment, because they were made in factories and shipped across...

Thus, "green" is not an absolute designation like positive/ negative. The term "green" loses meaning without qualification of HOW green something is. But it's hard to put a proportion on "green". If I said" I'm 15% green", would you understand? I'm suffering without a precise definition of "green".

I could say, A is greener than B. That makes sense.

There is difference between appearing green and actually being green. So many companies have jumped on the bandwagon. For example, water bottle companies are claiming that their "new designs" for water bottles are "green" because they use 30% less plastic. By "green" they mean it saves them money in manufacturing? The real question is: by how much is the state of affairs improved by a modified plastic bottle design, all things considered? I hypothesize that the new design isn't significantly greener than the old one, in the long run. (Considering the difficulty of recycling plastics, the litter problem, etc.) Maybe I'm wrong.

A is greener than B. Bikes are greener than cars, but bikes aren't green by themselves. Bikes take energy to move, just like cars. The fuel is the food you eat. Where did that food come from? It took energy to produce and likely it was done in an industrial way that produced trash, consumed energy for climate control and depended on petroleum for delivery. Even if you grow your own food and/or raise your own animals, is that really green?

By far, the energy we invest in fueling our bicycles is much less in comparison to motor vehicles, but it's not negligible; It should not be left out of the equation.

I saw a shirt the other day that had a picture of a bicycle and was claiming that the mpg rating for a bicycle is infinity. Well, that's true (after a fashion) because bicycles don't directly consume petroleum fuel. But if you go down the rabbit hole and trace the energy trail, the human's energy at the bike pedals isn't completely independent of fossil fuels. Thus, the shirt's assertion isn't unequivocally correct.

It can be overwhelming to trace the energy trail on anything we do. For example, I saw huge wind turbine blades carried by trucks on the highway recently, and it made me think of the energy cost of existence. To have a functioning wind turbine that is harvesting energy, a vast, possibly incalculable amount of energy must be consumed. Assembling it requires massive cranes, trucks, etc. Shipping it requires multiple trucks. Constructing it requires raw materials, a factory, etc. How many light bulb-hours were spent on a wind turbine blade? How many diesel engine hours? Computer hours? Going even further, what about the factory that makes the trucks and cranes? Consider the commuting energy of the crane operators, truck drivers, factory workers, engineers, etc. Another infinite branch of the endless energy trail. There must be a logical spot to draw the line when assessing an event's energy consumption. I'm thoroughly overwhelmed.

Moral of the story: reuse things

Fabric, The Final Frontier

Dog Wagon
I spent many hours on this trailer. Specifically I spent many hours at the sewing machine making the fabric enclosure. I am very proud of it. I used cordura fabric for the bulk of it. Cordura is commonly used on backpacks, cases, army boots and in other heavy duty applications. I broke several sewing machine needles before I found the right speed and needle size.
The windows are mosquito mesh.
The fabric enclosure is attached to the frame by an array of straps and snap buttons. It is in two parts: top and bottom. The top can come off leaving a general purpose floor. The door is like a hatch that is held on by velcro and snap buttons. All of it can come off for cleaning. All up and running, the trailer weighed about 25-30lbs, and would be very hard to pedal into the wind. I was aiming for an aerospace trailer that carries itself, but that will be the next one...
It came with reflective strips and even had a strap in the back to hang a bike light on.
I got the black cordura fabric because "black socks, they never get dirty..." but next time I will aim to get a bright color like yellow, orange, or white.
I took it for a test ride with about 100 or 150 lbs. I don't have an exact figure, but I know for sure that it was more weight than I recommend for trailer of this type. The load was junk from my yard: A cast iron sink, bricks, rocks, cinder blocks, gallons of water and motor oil. I took it over curbs at low speeds and on some hills and the trailer passed the test.

After the dead weight test I took TJ for some rides around the neighborhood. He got comfortable in there after he learned that he got snacks for being there. When riding, he even laid down and was looking out the window; Like he was taking a ride in the back seat of a car. I haven't done a complete inquiry into the effects of trailer motion on dogs. It's possible that they can get motion sickness.

Tuesday, August 17, 2010

Sunflower Style Trailer Now a Wino Drum Trailer!

This trailer gets used to haul around drums by noneother than Derek Hansen the drummer for WinoVino (
This trailer is like the one I made for the Sunflower co-op ( in June. I liked the style so I made another one with the slight variations that I described in a previous post. Its especially good for carrying plastic storage containers, as pictured above. With a little modification (adding some type of floor), it could also be used to carry things like drumsets, cellos, guitars, amps...

The cargo area is about 2' by 5' (feet).
It weighs about 25 lbs.

The frame is 90% made from electrical conduit, so it's kind of soft. If you go and drop it off of the 2nd floor or wail on it with a hammer, it will definitely bend, but for normal bike trailer purposes it will be fine. I make it out of conduit because it's inexpensive, readily available in 10 foot sections at home depot and I have a conduit bender already, therefore I can offer the trailer for a reasonable price. I know the Austin bike crowd. They don't want to spend hundreds and hundreds on a bike trailer. Seems like all the commercially available trailers nowadays cost $300 or more. That or they come from walmart.

The other 10% of the trailer is 1 inch square steel 14 gauge tubing. This is what serves as the frame member connecting the "dropouts" for the wheels. These dropouts are pieces of 1/4" steel with 14mm holes drilled in them for the axles.

The wheels are Wheelmaster 20x 1.75, alloy, 14mm axle, 48 spokes. I use them as stub axle wheels--the large diameter axle makes this possible.
This trailer uses the same type of tire, tube and hitch as the square style trailer seen below.

Square Style Trailer

32 inch x 34 inch cargo trailer.
Pictured with some sample cargo.
Cargo area is about 20 x 34 (inches).
It's made from 1 inch square, steel 14 gauge tubing. (14 gauge means the wall thickness is .083 inches, This is way more metal than needed for bike trailer purposes so it's on the heavy side, probably about 30 lbs, but it will carry 100 lbs and be square for decades. Also, if you are comparing with other trailers out there, you will find this particular combo of weight and capacity is not odd.
Link to, showing a trailer for about $180 that weighs 25lbs and is rated for 66lbs.

The wooden platform is some lightweight paneling. Not specifically designed for this application but it seems to do the trick. It would break if you slammed something heavy on it. Any 20 x 34 piece of wood or sheet aluminum would be good candidates for the cargo floor if it needs to handle heavy slamming. I can install it for you.

Tires: Sunlite 20x 1.75 Street tires, 40 psi.
Tubes: Pyramid 20x 1.75 schrader valve.
Wheels: Wheelmaster 20x 1.75, steel, bolt-on, 5/16" axle, 36 spokes.

Hitch: Burley standard forged hitch, with flex connector and safety strap kit. The heart of the hitch contraption is the forged aluminum piece (silver piece in pic above) that bolts onto the bike frame at the axle on the non-drive side of the rear wheel. Any common bike will work; quick release, bolt-on, horizontal or vertical dropouts. But if you have a brand new bike with disc brakes or some kind of fancy drop outs, this hitch will not work.

Lindsey's Bass Trailer!!!!!!!

Here is the trailer designed to carry a double bass + amp +other stuff. The wooden plank floor is somewhat temporary, as I will soon be learning about various types of fabric and how to work with them. My vision is for it to have a tough lightweight fabric floor, with detachable fabric sides and a rain/sun/wind cover that covers the whole thing. Stay tuned for developments in the fabric department.

In addition to the permanent fabric floor (that will be in reality soon), there is a detachable wooden floor made from 1/2 plywood (not pictured). Heavy duty stuff. It's strong, and it's really heavy. The complete wooden floor weighs about as much as the trailer frame by itself.

[By the way, I don't have an exact number but the trailer frame weighs a little more than a common bicycle, probably about 30-35lbs. I could see a reduction in weight if I were to switch to more expensive materials like thin-walled tubing of chromoly or 6061 aluminum. The reduction in weight would cause an increase in cost, no surprise. ]

Anyway, about the detachable wooden floor, it looks like a wooden stretcher, as it is cut to fit exactly into the trailer. The detachable (and heavy) wooden floor would be used for occasional trips in which the trailer needs to carry highly dense or sharp objects. The reason: fabric will tear if you concentrate the load at one spot. For example, if the trailer needs to go to a landscaping job and carry some tools like shovels, rakes and also some heavy bags of mulch and soil. Oh no! Wouldn't want the rake to pierce the fabric floor! :)

At first it was blatantly temporary, but now the plank floor is growing on me. I drilled out a bunch on holes in an attempt to save weight, and it made it look like swiss cheese.
A friend of mine joked that I should paint the wooden planks yellow like the rest of the trailer, then it would truly be the cheesy trailer.

The top cross pieces are not fixed in position, they are attached in such a way that they can rotate and be stowed out of the way in the case that the trailer is used to carry something taller than the side walls. Something like a 4x8 sheet of wood or mattress or...[fill in the blank]

There is also a detachable hoop piece that mounts to the two tube ends sticking out about halfway up. Most of the loading in/out happens through the back so it's been left off for a few days now. But it could be added to increase the side-to-side strength of the sidewall/roll-bar structure.