The Japanese have bikes made from recycled newspaper. I suspect it's all a matter of calculating the necessary thicknesses in the proper locations to deal with the loads.

The most important thing is: know how to do a hand calculation using basic statics principles. A bicycle frame is, relative to to the rider's frame of reference, simply supported, and the traditional 2-D case is statically determinate.

To extend to a 3-dimensional case, which may have various degrees of indeterminacy, use solid mechanics. Depending on what year you're in you may or may not know these yet. You can also choose to go to graduate school, where you can learn elasticity, which can deal with stress concentrations quite nicely. Or Timoshenko theory, which solves short beam problems.

Then, you can understand and criticize matrix/FE approaches. DO NOT start out with matrix/FEA without knowing the basic hand calculations.

Well, this thread has certainly covered a lot of ground. :-)

FEA, materials science, english grammar and composition, computer spell checking software, educational options for future growth, ...

As an engineer in industry for gettin on 25 years, I have some experience to share. First language and communication: it is still a problem for new and seasoned engineers. Some communicate with excellent clarity, and some do not. Sometimes a deficiency is due to skill and sometimes due to attitude. But being capable of more effective communication will make a better engineer.

Analysis and skills basis: One thing I have seen with some newer engineers with some more advanced tool (i.e. FEA) skills, is not being able to answer the question, "does your result make sense?" I have been guilty of this myself, so I'm not setting myself apart here as an embodiment of a standard. It is necessary to judge a complex result, in terms of potential correctness, and to be able to gain credibility by explaining the quality and limitations of your results. It's potential correctness rather than correctness, because an analysis is a prediction of reality, and the only way to absolutely determine if it's correct is to perform physical testing. One can imagine that in say, the space vehicle industry, this is not always possible. So you have to instead be able to judge it on the basis of making sense.

Determining how you want to answer the "make sense?" question is a choice, but what I've found for circuit design and EM field related work is to be able to simplify a system down to a level that facilitates quick hand analysis, and to perform such analyses to find what ballpark a detailed prediction has to lie in. This requires all those undergraduate skills that we may have hated back in school, but it's why those are still necessary, even we have a supercomputer on our desk.

Last, as my earlier comment emphasized, there's a lot more to finding the "optimum" design than maxing out the technical properties. The first major issue is to define "optimum." This involves understanding the needs the end product must fulfill and how those relate to the technical properties of the product and all its parts. This is not or at least in my days was not taught in engineering school.

Good luck to all you young engineers! I hope my industry (automobiles) still has room for all of you when you are in the job market!

Road Fan

Just some thinking about the topics:

Bamboo is one of my absolute favourite things, but I am not sure I would dare to make bikes and sell them to peopel, risking being sued if something goes wrong. If peopel treat theyr bamboo bikes the way they treat theyr "normal" bikes I`d be scared to ride them. I am thinking bamboo bikes is best suited for peopel who know the material well, and best for somebody to pick the bamboo and build it themselves. Just my thinking.

Also what came into my head is that the bicykle has been unchanged for more than one hundred yrs, I suspect the best has been found. For me personally the mixte is the perfect frame. I guess you need to look into if something must be changed since you are building out of baamboo.

Edit: Realised now you do not ask about best geometry but best choice of Bamboo for needed strenght.

Then the spelling. This is happening all the time, and I find it plain cruel what some peopel are doing. This means most peopel should stay away from this forum since English is not theyr native language (like me), or they are dyslectic, or they`we got a disease that affects theyr consentration (like me), or they`we got a crppy keyboard who does not always obey (like me)..

What If I said:" Seriously, Why do`nt you build your own wheels? The world would be so much better for the rest of us (and for you) if you could do that, and you would not bother the rest of us with your crappy wheels". Get a life!

Roadfan,

I believe in testing. I believe in analysis as a tool to support testing. All too often I have seen analyses done which confirm a certain design but when it's tested (properly) it fails,...fails completely. I have seen analyses get re-done which are only then able to explain the failure and guide the resolution.

Without the test failure, the modelling would never have been done with enough fidelity to ever show the problem. The analyses that need to be done are quite detailed and many (most?) engieers cannot do them. This is especially true of composites work, where failure starts at an almost microscopic level but propogate into large scale delams and broken fibers, etc.

I believe in test. Use the analytical tools to help plan your test program.

If you have a disability (such as dyslexia) or the language is not native to you, I don't think you will get any grief from most people. If you have lived in the US (or other place where English is the language) for several years, you should learn the language. If I lived in Taiwan or Japan or Germany or even France, I would learn the language.

If English is your native language, you should know and use proper spelling, grammar and syntax. It's as simple as that. It is not a "put-down" (insult). It is good advice. Learn to accept good advice gracefully. It is usually given in an attempt to help.



I agree about not selling bamboo bikes, at least not yet. Product liability suits can ruin your life.

I`we seen alot of bullying about spelling in the forums, and most of them is NOT good advice. Also, how can you be sure why somebody is spelling / writing the way they do?

Came here to give you this link http://www.bikeforums.net/showthread.php?t=488635 just found it.

Mike, basically you're right about testing and I agree with what you say, and where possible it's what I do. However in the three industries where I have extensive experience (automotive, high energy physics, and space flight), I know that not all tests are possible or practical. In the early stages of projects, especially projects to deliver totally new technology such as in space programs, you cannot test the behavior of every space vehicle design configuration IN ORDER TO SELECT one (i.e. in the initial stages of the project), because they are not built. Plus, the customer will not pay you to build every possibility. Many decisions can only be made based on engineering analysis in the early stages of a project. At strategic points you make exploratory and confirmatory tests to better understand the implications of a design that has been chosen, or to confirm the validity and durability of the design.

The OP was talking (IMHO) about finding the requirements for the frame members, so that an adequate set of bamboo frame members could be designed and joined. This is most efficiently done with engineering analysis, not cut and try testing. Validating the design is best done by prototyping and testing.

Road Fan

I understand, the thing is, without a good set of material properties you cannot do the analysis. Materials properties are measured (a test). What I would worry about with bamboo, like wood, is the variability of the material properties associated with growing conditions, internal flaws, "termites", storage conditions, moisture content,... Unless one has nearly control over these things, one cannot control the properties.

Yes, that's all true, I'm glad I'm not the one who's taken on this task. I'd need the energy of a 20 year old undergrad to sort out all those new issues. I'll stick with minor problems like detecting vehicle-vehicle collisions with on-vehicle radar.