While a piece of steel is obviosuyly much stronger than a piece of wood of the same dimensions, if we stipulate equal *weights* rather than equal dimensions, the piece of wood may be stronger. The "specific strength" (or "strength to weight ratio) of some woods like balsa are greater than most steels.
That means that the applications of wood overlap the applications of steel somewhat. Some places where you need a little steel you can use a lot of wood and the result will be equally strong and weigh about
I'd take your post more seriously if you didn't make absurd generalizations like "steel is very stiff and wood is very flexible." From that alone it's obvious you understand nothing about materials.
I'd take your post more seriously if you didn't make absurd generalizations like "steel is very stiff and wood is very flexible." From that alone it's obvious you understand nothing about materials.
Alright then. Woods have a Young's modulus (along the grain) of around 3-12 GPa. Typical construction steels have a modulus of around 200 GPa. Therefore a steel beam will be stiffer than a wooden beam of identical dimensions. However, I do realize that *some* wooden objects will be siffer than *some* steel objects. For example an oak beam with a 10x10" cross section will be stiffer than a steel bar of the same length with a 0.25 x 0.25 inch cross section.
You probably already know all this, but for what it's worth, Gary Klein's realization that you can build a stiff frame out of anything if you just increase the diameter enough is completely apropos for wooden bike frame design. The problem, as the Renovo guys have found, is that you need like 5" diameter tubes to get even acceptable stiffness, since stiffness rises as the third power of diameter for tubes. But at those diameters, for a competitive weight, the walls have to be like sub-millimeter in thickn
I certainly remember when Klein's bikes came out; he was a few years ahead of me at MIT. I don't know if the larger tubing idea was actually his; he was part of a group of students working on an aluminum frame. The relationship of diameter to stiffness had neen known for centuries; I think Euler originally worked out that the bending stiffness of a beam is proporitional to the moment of inertia of its cross section. I expect a lot of engineers realized the potential of aluminum. What stands out about Klein is is entrepreneurial energy.
My take on the bike in question is that it's interesting in that it shows the potential of the tools used to make it, but not quite as interesting in terms of what it shows about the potential of wood as a material. I'm hoping that somebody, someday will come up with a very interesting and surprising wood bike that really makes the most of the material and probably won't look much like a conventional bike.
Here's a curious fact about wood. (Score:2)
While a piece of steel is obviosuyly much stronger than a piece of wood of the same dimensions, if we stipulate equal *weights* rather than equal dimensions, the piece of wood may be stronger. The "specific strength" (or "strength to weight ratio) of some woods like balsa are greater than most steels.
That means that the applications of wood overlap the applications of steel somewhat. Some places where you need a little steel you can use a lot of wood and the result will be equally strong and weigh about
absurd generalizations (Score:2)
I'd take your post more seriously if you didn't make absurd generalizations like "steel is very stiff and wood is very flexible." From that alone it's obvious you understand nothing about materials.
Re: (Score:3)
I'd take your post more seriously if you didn't make absurd generalizations like "steel is very stiff and wood is very flexible." From that alone it's obvious you understand nothing about materials.
Alright then. Woods have a Young's modulus (along the grain) of around 3-12 GPa. Typical construction steels have a modulus of around 200 GPa. Therefore a steel beam will be stiffer than a wooden beam of identical dimensions. However, I do realize that *some* wooden objects will be siffer than *some* steel objects. For example an oak beam with a 10x10" cross section will be stiffer than a steel bar of the same length with a 0.25 x 0.25 inch cross section.
There, is that pedantic enough for you? Or do I
Re: (Score:2)
You probably already know all this, but for what it's worth, Gary Klein's realization that you can build a stiff frame out of anything if you just increase the diameter enough is completely apropos for wooden bike frame design. The problem, as the Renovo guys have found, is that you need like 5" diameter tubes to get even acceptable stiffness, since stiffness rises as the third power of diameter for tubes. But at those diameters, for a competitive weight, the walls have to be like sub-millimeter in thickn
Re:absurd generalizations (Score:2)
I certainly remember when Klein's bikes came out; he was a few years ahead of me at MIT. I don't know if the larger tubing idea was actually his; he was part of a group of students working on an aluminum frame. The relationship of diameter to stiffness had neen known for centuries; I think Euler originally worked out that the bending stiffness of a beam is proporitional to the moment of inertia of its cross section. I expect a lot of engineers realized the potential of aluminum. What stands out about Klein is is entrepreneurial energy.
My take on the bike in question is that it's interesting in that it shows the potential of the tools used to make it, but not quite as interesting in terms of what it shows about the potential of wood as a material. I'm hoping that somebody, someday will come up with a very interesting and surprising wood bike that really makes the most of the material and probably won't look much like a conventional bike.