DIY bicycles built of wood

It is deforestation that has to end, not forestry.

The world’s forests have been under pressure since the dawn of the industrial revolution, and the biological diversity that they harbor – the wild nature which created the fertile land and breathable atmosphere that we take for granted – remains at great risk as the demands of the world’s industrial economy continue to grow.

Tropical regions are one of the destinations of Simple Cycle technology, and we have to ask what effect our project might have there. We know that tropical forests are being cut down to make way for cattle ranching and palm oil plantations to feed growing human populations. Tropical forests are also being cleared to make room for monoculture rubber plantations that serve to put tires on the world’s cars and trucks (and yes, bicycles too).  Tropical forests have been clear cut for their lumber, and then replaced by cattle pasture or plantations, rather than being encouraged to go back to native forest. None of these harmful practices do we wish to exacerbate.

Utilizing Simple Cycle wood-frame technology can help preserve our forests. We do not have to destroy any type of forest in order to have a modest amount of wood. Harvesting wood for cycles on a small local scale no more ruins a forest than do the activities of woodpeckers and beavers. Human impact is largely a matter of scale. Removing a fallen, diseased, overcrowded or dead tree here and there need not have a profound ecological impact. The method of logging chosen makes a critical difference, and industrial clear-cut logging is very different in carbon cost and habitat impact than careful small-scale selective harvest. 

There are even ways to harvest wood without killing a tree. Daisugi is a Japanese Bonsai technique which produces straight and knot-free poles without felling the tree. Pollarding is a similar European technique where arborists severely prune trees (with new growth of buds and leaves emerging above the reach of livestock) at intervals of eight to fifteen years, a pruning cycle which produces defect-free poles for fencing and construction. Coppicing cuts trees (of species known to reliably re-sprout) down to a low stump, which then puts forth new shoots. All of these systems greatly lengthen the life of the tree by delaying its senescence. 

Rocky Mountain Aspen, a softwood which we sometimes use, is one of a number of species of tree that grow in clonal groups. Forest fires or timber harvest leave the Aspen’s shared root system intact to nourish re-growing stems, thus allowing the clonal group to maintain canopy dominance for many centuries. 

We acknowledge that certain habitat types are more rare or more fragile and should be treated gently or left alone entirely. We have scientific understanding enough to manage forest lands without ruining watersheds, robbing soil fertility, driving species to extinction, and worsening the desperation of the rural poor.  We do not need to impoverish the forest environment by felling giant ancient trees. The very small scale of Simple Cycle technology makes taking these basic precautions highly achievable.

A QUICK CALCULATION FOR PERSPECTIVE 

Building Simple cycles of wood represents an extremely modest and manageable demand for lumber. The average Simple cycle frame is made up of about 1 cubic foot (30cm X 30cm X 30cm) of wood. A single typical mid-size pine or fir tree may yield 70 cubic feet of lumber, enough for 70 wood-framed Simple cycles. A pine/fir forest (our example here is from northern Idaho) may have 500 medium-size trees per acre (1200 trees per hectare). An acre of such forest, thinned by 30% in a selective cut, could produce lumber for 10,000 cycles, a level of harvest that would leave a healthy stand of forest behind. A managed stand can actually be ‘healthier’, in that trees infested with forest-killing bark beetle larvae – overpopulating in Idaho because of a warming climate – can be targeted and removed. In as few as 15 years the amount of tree-biomass on the landscape will grow back to pre-thinning levels. Wood for a billion cycles could be produced by the thinning of one hundred thousand acres, which is an area of productive pine forest 12 miles by 12 miles (18 x 18 kilometers). Fifteen such blocks could be fit within Shoshone County, Idaho. This county contains a mountainous landscape blanketed by a productive ‘second growth’ (already logged once) forest of Ponderosa Pine, Western White Pine, Douglas Fir, Hemlock and Western Red Cedar, a habitat wherein live Elk, Mule Deer, Whitetail, Bighorn, Mountain Goat, Moose, Black Bear, Mountain Lion, Wolf, Lynx, Bobcat, Wolverine, Fisher, Mink, Marten, Skunk and Weasels, along with a full complement of small mammals, birds, amphibians, riverine fish, understory plants, arthropods, and – with the greatest mass of all – microorganisms and fungi. After careful selective logging as described above, every one of the inhabitant species listed would remain still present on the landscape. The last Woodland Caribou was driven north out of Idaho in 2018 by clear-cutting, highway paving, urban development and climate warming; if each of these changes could be ameliorated, a careful harvest of timber could help re-create conditions which might allow the Woodland Caribou to reestablish. The amount of forested land found in this single (large) northern-Idaho county (which represents 0.0001% [one ten thousandth of one percent] of the Earth’s 4 Billion hectares of forest land) could produce, under careful and conscientious management, a wood-framed Simple cycle for every human being on earth, every 10 years, indefinitely into the future. Sustainably. Just one county. If such a timber harvest were dispersed worldwide, this level of use would be essentially undetectable.

Unlike virtually all other industrial materials, carefully harvested wood and bamboo (and hemp and flax and grass fiber) that is used in durable applications sequesters carbon, rather than releasing fossil carbon to the atmosphere as conventional bicycle manufacture does. 

In the study Environmental Impacts of Redwood Lumber (Sahoo and Bergman, 2019), researchers found that lumber from small second-growth Redwood trees stored 12X more greenhouse gas than was released by fossil-fueled machinery and drying kilns during that lumber’s harvest and processing. 

The carbon-cost of shipping is avoided when native materials are sourced at point-of-use.

Modular metal hardware permits full reuse or straightforward recycling, thus spreading energy investment over multiple vehicle lifetimes. All Simple subassemblies can be easily dismounted whole-and-reusable from the assembled cycle. Simple subassemblies are non-composited and thus fully-recyclable material.

No materials that are difficult to reclaim and recycle are specified.

No waste need be sent to landfill in the manufacture or decommissioning of Simple cycles.

Cradle-to-grave lifecycle carbon cost of a Simple cycle is extremely low, even for a bicycle. 

Discarded shipping pallets are a source of two-by-fours and one-by-fours (or close equivalents), in dimensions usable (and often near-perfect) for Simple cycle frames. Shipping pallets in the US are usually made either from hardwoods like oak (decking), and from various types of pine (stringers). Used pallets are to be found worldwide, even in areas without forests.

A single standard 40” x 48” pallet in decent condition is usually sufficient to build one Simple bike, small trike, or handcycle frame.

The neglected pile of pallets in the photo shown here produced a number of deck boards of solid, sound, attractive (after sanding) white oak. The two-by-four stringers were pine, perhaps half of which were usable. 

Many of the nails were recovered and straightened—ready and capable of holding a cycle together, just as well as they did the pallet. 

Many of the prototypes pictured in this website demonstrate the use of reclaimed pallet wood.

Listed here are the sizes of boards that we have been designing with. Building with boards of these North American dimensions usually requires no changes to the boards’ widths and thicknesses, only that they be cut to length. Certain model/component combinations may require a small board of non-standard thickness, extra work to shave off an area of excess wood, or the addition of shims. 

Our construction methods allow international metric near-equivalents to be used with no modifications. Three-quarter inch boards (19mm) can be doubled to create one and a half inch boards (38mm), often with consequently enhanced strength, durability and straightness.

(the disorganized table  below is under development at this time)

North American Nominal Size (named in inches)

Actual Finished Size in Inches

Actual Size in Millimeters

Near-Equivalents in common use internationally

Metric Measurements in exact inches

1x2 "one by two"

¾ x 1.5”

19 x 38 mm

25 x 44 UK

19 mm = ¾”

1x4 "one by four"

¾ x 3.5”

19 x 89 mm

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1x6 "one by six"

¾ x 5.5”

19 x 140 mm

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2x2 "two by two"

1.5 x 1.5”

38 x 38 mm

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38 mm = 1.5”

2x4  “two by four”

1.5 x 3.5”

38 x 89 mm

45 x 90 Australia, 38 x 76 So. Africa, 44 x 96 UK

89 mm = 3.5”

2x6 "two by six"

1.5 x 5.5”

38 x 140 mm

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140 mm = 5.5”

In many tropical and near-tropical areas, bamboo is native, prolific, highly available, and a dominant building material. Here is what we know so far about its potential use in building Simple cycles:

Extracting this resource from the local environment at a small scale generally has a very low environmental impact. Bamboo stems grow very rapidly. When the stem is harvested, its roots are not cut, and the plant can continue growing without the need for replanting.

Even more so than boards from trees, bamboo can be cut, collected and processed by hand, using minimal tools – a substantial advantage for an owner-builder individual. 

Bamboo can be air-dried; kiln drying is not essential.

The large amounts of starch present in bamboo makes it highly attractive to mold and fungi, termites and powder-post beetles, which can cause much damage during drying, storage, and subsequent use. Inundation in water is used to leach out the starch. 

Carbonization (baking) is used on split bamboo to burn out the sugars.

“Fixing” preservatives are used to preserve bamboo for outdoor usage (which would include Simple cycle usage); choices include Copper Chrome Arsenic, Copper Chrome Borate, Creosote, Trichlorophenol, and Naphthenates of copper and zinc. We do not yet know how critical these chemicals are, their health risks, nor their cost.

Stems can be used with minimal processing in the hand-labor-intensive fabrication of those products which retain the distinctive appearance of the material – furniture, for instance. 

Alternatively, the stems can be industrially processed into fiber, dimension lumber, and engineered panels, processes in which the plant’s recognizable appearance is lost and energy consumption is substantially increased. Export also adds dramatically to the energy embodied in a bamboo product when it is used far from the area in which it grew. In the US – where virtually all bamboo products are imported – the cost of imported dimensional bamboo lumber is about 1.5X the cost of American red oak dimension lumber.

The Simple Cycle Project’s interest in bamboo is focused on its potential as a durable, locally-harvested and owner-processed material. We are very early in this evaluation, as we do not live and work in bamboo habitat.

Lumber and Bamboo resource availabilities are not necessarily geographically distinct; in Sub-Saharan Africa they are often to be found in the same regions. The differences in detail of their distribution tend to be local, and mostly follow elevational temperature/precipitation variation. It is for this reason of common distribution that the marriage of the two materials can prove to be both workable and advantageous.