Why build a bicycle frame out of wood? That is probably the number one question I get from people who see my wooden framed bicycles. The answer is multifaceted, ranging from simple to quite complex. The very first bicycles were made of wood. If you have the opportunity to visit the Bicycle Museum of America in New Bremen, Ohio, you will see many fine examples of antique wooden bicycles.
Wood offers unparalleled opportunities for design flexibility. “Tubing” shapes and cross-sections are literally infinitely variable. In addition to unlimited geometrical possibilities, there are hundreds, if not thousands, of wood species to choose from. Even within a given species, there are opportunities to custom tune a frame. Grain orientation and the activity of the cambium tissue in forming new wood (AKA annular rings) are just a couple examples. The coatings and surface treatments of wood are additional custom tuning possibilities for a wooden frame. Wood also offers some rather unique opportunities for aesthetic creativity including, but not limited to, carvings and inlays.
The ride of a wooden frame bicycle depends on the aforementioned variables. As is the case with any frame material, a wooden frame can be made flexible and “whippy” or stiff and unforgiving. I’ve ridden bikes with Titanium, aluminum, steel, man-made-FRP (Fiber Reinforced Polymer, e.g. carbon fiber) and God-made-FRP (e.g. wood). With an admittedly biased opinion, I would rank ride quality in the following order: wood number one, steel – a close second, titanium third, carbon fiber forth and aluminum a distant fifth. One attribute that sets wood apart from its metallic and plastic counterparts is its superior ability to dampen road vibration.
The strength and durability of wooden bicycle frames is a paramount concern. Grain orientation plays a tremendous role in the strength of the wood. Consider the example of a martial artist breaking a board with her bare hand. If a ¾” thick, pine board is positioned so that the wood grain runs parallel to her hand, the board breaks relatively easily. If the same sample is positioned so that the grain is perpendicular to the striking force the board may not break at all and if does, her hand will hurt. Now try the same experiment with a ¾” thick piece of eight-ply, Birch plywood. The result would most likely be a broken hand, not a broken board. I have tested frames according to American Society for Testing and Materials (ASTM) standards. When the wood grain is oriented so that the load is parallel to the principle stresses in the frame, the frame will not meet ASTM standards. Conversely, if the grain is oriented so the load is perpendicular to principle stresses, I’ve witnessed frames that not only met ASTM standards, but the yield point was actually higher than that of frames made of aluminum.
Like any other bicycle frame, the longevity of a wooden frame is dependent on maintenance and treatment. Part of the beauty and experience of owning a wooden framed bicycle is that there is something that can be done easily to maintain, preserve and even enhance its appearance. I like to use wipe-on gunstock oil finish on my frames. The rule of thumb for gunstocks is “a coat a day for a week, a coat a month for a year and a coat a year for a lifetime.” I recommend the same regime for a bike frame. It takes anywhere between an hour and four hours, depending on how much disassembly of the bike you want to do. The process is simple: clean the surface with water and detergent, lightly scuff the surface with synthetic steel wool (like scotch-bright), dampen a rag with gunstock oil and wipe it on. Allow it to dry overnight. The beauty is that practically anyone can restore the finish himself. In contrast, properly restoring a metallic frame requires expensive tools, lots of experience and a host of hazardous materials & personal protection gear. One of my greatest experiences on a bicycle involved building a ramp at the end of a pier and launching my steel-framed BMX bicycle into the lake when I was in middle school. I wouldn’t recommend this kind of treatment of a wooden framed bicycle. I take great pains to properly seal the frame inside and out but intentionally submerging the frame would be cruel and unusual treatment. I certainly don’t shy away from riding my wooden framed bicycles in the rain. As is the case with any quality bicycle, I try to store it inside whenever possible. When my family cycle toured Europe on wooden bicycles, it rained some almost every day as we pedaled through central Germany. We camped so the bikes were outside, 24-7. I completely disassembled, cleaned and refinished them when we returned to the states. It was interesting to see that the steel, sealed cartridge bottom brackets were rusty but the wood was virtually unaffected. One of my students expressed concern about how my bikes would hold up in a fire. I assured her that if I was riding my bike through fire, I would have far greater concerns than the welfare of my bicycle.
Building a wooden bicycle frame is fun! I started building steel bicycle frames as a hobby in 1977, when I was a junior in high school. I think there are several things that make building wooden frames more fun and practical than building metal frames:
1) There is no need to tackle the steep learning curve of welding or brazing, not to mention the great expense of welding equipment and expendables.
2) The fixtures do not need to be fireproof like they would need to be if welding so they can be built inexpensively with basic woodworking tools.
3) Cold-forming is the metal-frame builders dirty, little secret. Metal always “moves” when it is welded. The builder has to force the frame back into shape using Herculean strength and long pipes for leverage. Wood pretty much stays put where it is laminated.
4) Wood is sustainable. It’s hard to find anything “greener” than a tree. As a matter of fact, a wooden frame could be manufactured off the power grid.
5) Fewer hazardous materials. OSHA (Occupational Safety and Hazard Association) requires Material Safety Data Sheets (MSDS) for all “hazardous” materials used in my shop. I took inventory: four wood-frame related MSD Sheets compared to fourteen required for substances used to build a steel frame.
6) Metalworking stinks. The litmus test is when I return home from working in the metal shop and my wife immediately points me toward the shower. I get the opposite response when I’ve been working in the woodshop – embraces and comments like “you smell good”.
7) It is awesome in the true sense of the word. As the rough boards are run through the planer and the beauty of grain is revealed on the other side, it’s like opening a present. There is a second revelation (“ooh-ah” moment) when the frame is all sanded and the first coat of finish is applied. The grain of the wood explodes into beauty with unexpected figures and colors.
Building a wooden bicycle frame isn’t exactly a panacea. It takes far more time to build a wooden frame that a metal, plastic or a bamboo frame. Please don’t underestimate the hazards of woodworking. Airborne dust particles and the danger of cuts and amputations are very real. Some people are highly allergic to certain species of wood dust. Walnut, my personal wood of choice can be a formidable allergen.
The obsession with lightweight bicycles is controversial and frankly somewhat irrelevant. Many well know manufactures are wisely refusing to list the weights of their bicycles. Listing weights subjects them to the scrutiny of the self-proclaimed “weight weenies” that build websites comparing and quibbling over weight inconsistencies that amount to the weight of pocket change. Wooden frames compare favorably with the weight of aluminum or high-end steel frames. I built one wooden frame that was 280 grams lighter than an ultra-light steel racing frame that was the same size. Big deal! That kind of weigh differential can be accomplished by the rider consuming a burrito (okay…a rather sizable burrito).