About Bamboo

This blog was founded upon the idea that promoting renewable materials can make a difference in the planet. So why bamboo? What about this woody grass makes it so sustainable? Furthermore, what makes bamboo a viable alternative

to traditional lumber? Green is great, but strength is what stands the test of time. Turns out, when up against other timbers, bamboo shoots above and beyond.

Strength and Durability
Thanks to its unique composition, bamboo is naturally designed for strength...

• Unlike wood, bamboo has no rays or knots, allowing it to withstand more stress throughout the length of each stalk.
• Bamboo’s sectional anatomy, both as a cane and on a microscopic fiber level, enhances its structural integrity.
• The high silica content in bamboo fibers means the material cannot be digested by termites.
• Bamboo contains different chemical extractives than hardwood, which make it better suited for gluing.

As a result, in structural engineering tests bamboo has been shown to have...

• Higher tensile strength than many alloys of steel
• Higher compressive strength than many mixtures of concrete
• Higher strength-to-weight ratio than graphite

Selecting Bamboo There is surprisingly little on the web about how to choose bamboo species. I have done a fair amount of research and have figured out a few things through trial and error. Finding it. Sure it can be hard. I grew my own, however not everyone lives in a temperate climate and there are numerous commercial sources. The species I grow is Seashore Bamboo (bambusa malingenis) which is closely related to Tre Gai since it is a very thick wall bamboo and is least prone to splits and cracks. Notice how thick the walls are in the photo to the right compared to a "decorative" bamboo pole. It is important that you choose older bamboo poles. Younger poles are not fully developed structurally. Also some poles are born to split, its better to have a pole that his demonstrated its worthiness for your bike. You can generally tell the older poles by looking for weathering, if it looks like a polished pretty thing, its probably very young. Second, the poles will have the thickest walls near the base of the pole. These thick-walled pieces would be a good choice for your longest structural parts since these bears a lot of weight. Choose your pole carefully. Third, the nodes on the pole are the weakest point. The individual fibers traverse to the other side of the poles. This is apparently the weakest link, so try to avoid using them for structural components. Fourth, respect the bamboo. Each piece is different. Try to figure out how best to use bends, thick walls, etc to better suit the build characteristics of your bike. Also, don't expect your bamboo to be straight Bamboo Growth Cycle The first unique aspect of bamboo is that it can reach its full height and width in a single three-four month growing season. Trees and other woody materials cannot. The clumps of new shoots grow vertically in this first season, and do not branch out or flower. In the second year, the outside pulp-like wall of each stem or “culm” becomes dry and hard. The individual nodes begin to sprout small branches and leaves. In the third year, the culm fully hardens, and the bamboo shoot is not considered fully mature. In the standard life cycle of bamboo, fungus and mold begin to develop on the outer culm within the first five to seven years of its life. Within the decade, the fungus and mold will overtake the bamboo, causing it to collapse in on itself. For this reason, harvesting bamboo for use in a bike is best completed after full maturity at age 3, until about age 7, depending on the species. My Seashore Bamboo (bambusa malingenis) is best during year four. Comparison of the mechanical properties of natural bamboo with other materials Material Density (g cm 3) Tensile strength (MPa) Specific tensile strength (N mg-1) Tensile modulus (GPa) Specific tensile modulus (kN mg-1) Compression Strength (MPa) Specific Compression Strength (N mg-1) Wood 0.46 104 226 10 22 7 80 Concrete 2.5 4 2 48 19 69 28 Glass 2.5 50 20 69 28 50 20 Aluminum 2.7 247 88 69 25 - - Cast iron 7.8 138 18 207 26 120 15 Steel (0.06% C) 7.9 4.59 58 203 26 800 101 Polyester 1.8 276 153 18 10 270 150 Epoxy 1.8 1100 611 45 25 400 222 Bamboo 0.66 206 312 20 31 79 120 It's interesting to note that bamboo outperforms wood by a 2:1 factor and compares favorably to aluminum.