I built a bamboo bike frame over the summer. It's super fun, both to build and to ride. I was inspired by Brano Meres' excellent Instructable, ayasbek's Instructable, and, of course, Craig Calfee's bikes. My method is slightly different, so I decided to document it. Beware: I underbuilt the bottom bracket joint and it cracked; I'm currently looking at vacuum bagging to make the joints much stronger. I will update this Instructable once Bamboo Bike Mk. III is done (this one is Mk. II).

DISCLAIMER: If you try this, it's your fault if it breaks and you get hurt. Frame failures are no fun, and if you build this and your frame fails, it is very possible you will get hurt. Don't blame me.

The basic process will be:
1. Get materials!
2. Design the frame
3. Heat treat the bamboo
4. miter the tubes; the head tube and the bb shell will be metal parts that fit inside bamboo sheaths.
5. Tack it all together
6. Reinforce the joints
7. Build up a bike
8. Ride!

Step 1: Materials and Tools

Materials you'll need:
- bamboo, of the appropriate sizes. I got mine from OSH. They had " 1" Bamboo ", which in reality ranged from .75" to 1.25" in diameter, and " 1.5" Bamboo ", which in reality ranged from 1.25" to 1.875". I used .875" for the rear triangle and 1.5"-1.75" for the front triangle. It's definitely strong enough.
- hemp fiber, or fiberglass, or carbon fiber. I used hemp fiber from hemptraders.com. Fiberglass is cheap and available at OSH. You can get carbon fiber ( and fiberglass, too) at fiberglast.com .
- epoxy resin and hardener. 10 minute pot life worked well. I got mine from West Marine, and it's available at fiberglast.com too.
- 5-minute epoxy. Or 30-minute, or 2-hour, it really depends on how patient you are. I got them from OSH.
- a head tube and a lugless bottom bracket shell. I got mine from novacycles.com .
- dropouts. I got mine from ebikestop .
- expanding foam. I'm not sure if it is needed, but Brano Meres seems to think foam does good things, so I put some in the rear triangle. It helped keep the dropouts in their place when it was all getting tacked together. It's light and cheap, and I got it at OSH.

Tools you'll need:
- a propane torch, or a heat gun. This isn't necessary if you can breathe fire. It's for heat treating the bamboo. Mine is from OSH.
- a hacksaw or a coping saw. This is for mitering the bamboo, and for cutting the tube to length. Mine is from Home Depot, I think. You probably have one already, though.
- if you have a drill press, I hear you can get an attachment that holds a tube at an angle so you can miter quickly and accurately. thavinator posted this link in the comments which points you toward where you can buy them.
- a half-round wood rasp. This is for mitering the bamboo. Got it from OSH.
- tubemiter.exe . Invaluable when mitering. Mitering tubes. Not so useful for mitering other things.
- a Dremel. Useful for everything. I bummed one off a friend, but I was almost done with the frame at that point. This would have made things go much faster.
- disposable gloves. Epoxy is bad for you, don't touch it. Costco sells these in bulk. Your local drug store will carry them too.
- a mask; epoxy and sawdust and the like is bad for you. Don't inhale it. OSH.
- a jig. I got aluminum from OSH and built the almost jig by dr welby . Well, you technically don't need one, but I found it to be very useful. You'll also need clamps if you use a jig.
- calipers are nice to have. I "borrowed" mine from my school's robotics lab. Harbor Freight carries them cheap, though. Measuring tape is also important.
- a protractor is important to have. Angles are important to get right.
- a Sharpie, or something else that marks up just about anything.
- trash bags; they are useful for making the joints.
- scissors.
- a camera, so you can document your work.

You'll also need bike components. I bummed around and got some free, and bought some for cheap. Total cost of the entire bike: about $300.

Step 2: Design!

I CAD'ed my bike in SolidWorks, to make sure that I had clearance for everything. You can try to copy a bike you particularly like, or draw something out on paper. Then set up your jig according to your design. Simple, yet very important.

I don't actually know much about frame design. I did a little bit of Googling, a lot of looking at pictures of bikes, and a bunch of poring over the geometry charts published by bike companies. Then I used SolidWorks to check for clearance. You don't want to finish your bike to find that your pedals almost scrape the ground, or, worse yet, hit your rear triangle!

I "tested" my bamboo for strength by stacking bricks on it, sitting on the bricks, and then leaning to one side. It was so rigorous. My bamboo withstood about 300 ft-lbs of torque.

I found a picture online that has the names of the tubes of a bike frame. It may be useful to you.

Step 3: BB Shell, Heat Treating

I cut a short piece of bamboo to act as a sheath for the BB shell, and then used a rasp to increase the inner diameter until the bamboo fit over the BB shell.

Heat treat your bamboo first, as there is a little shrinkage that happens when you heat-treat. I learned this the hard way. When heat-treating, I found it easiest to have the flame be very small and be very patient. Heat treating strengthens the bamboo by caramelizing the sugars inside it, bonding the fibers closer together. It also looks nice.

Step 4: Mitering

This was easily the most labor-intensive part of building the bike. I had decided that using the joints from old bike frames was cheating, so I had to miter each joint by hand instead of just cutting the bamboo and fitting it on.

The seat tube is mitered to the seat tube at 90 degrees. Print out a template from tubemiter.exe, cut it out, tape it onto the tube, and go to town! First, I Sharpied in the line so that I could see the edge better. Then, I cut longitudinal slots down to the line, so that the bamboo would chip off as I sawed along the line. Then, I sawed along the line, and I finished with rasp work. After testing it against the actual piece I was mitering to, I did some more rasp work. And then tested again, and then some more rasp work. And so on, until I achieved a good fit. It doesn't have to be super tight, since you are tacking the two together with epoxy and not welding it, but it can't be *too* bad of a fit.

For the down tube and the top tube you will have to miter both ends, and they both have to be straight. The down tube will also have to be mitered to two tubes. My best advice is to be patient and careful. Use your protractor to check if your angles are the same in real life and in your design.

For the seat stays I used this calculator instead to make templates for the offset miters.

The bridges are very small, so they are hard to miter. I included pictures of how I did it.

Step 5: Tacking

Now tack everything together on the jig, with epoxy. Easy enough. Make standoffs for the jig as described in that instructable (but I used epoxy instead of welding it). I used string to tie the tubes to the standoffs, as I had no tube clamps and bamboo does not get attracted to magnets. It actually worked pretty well.

For the front triangle, I first tacked the seat tube to the BB shell.

Then I tacked the head tube to the down tube.

Then I attached the seat tube and BB shell to the upright part of the jig, and tacked the down tube/head tube assembly to the BB shell/seat tube assembly.

Then the top tube was slid in and tacked. For this, I actually had the front triangle (actually a front V at this point) lying flat on the table.

For the rear triangle, I filled the tubes with expanding foam first. I capped the ends with tape to hopefully force the foam to expand inwards. The seat tube was replaced on the jig upright, and the dropouts were bolted to the dummy axle. I put the rear triangle tubes into place, using the dropouts to poke holes in the foam, which held everything in place while the glue dried.

Tacking is the best, it's not very messy and your frame looks almost rideable! Don't try riding it, though, you'll just hurt yourself and your frame will be in pieces again.

Step 6: Reinforcing the Joints

This is the single messiest thing I have ever done, and also has probably contributed the most to my future cancer. Wear gloves, and wear a mask.

Masking comes first. If you haven't spread newspaper or cardboard all over your workspace yet, do so now. Use several layers of newspaper - this stuff soaks pretty well. Also, mask off the parts of your frame you don't want to have to scrape epoxy off of afterward.

If you've got vacuum bagging equipment, use that instead of this method I'm about to describe.

1. Cut up some strips of polyethylene (trash bags) and keep them handy.

2. Then get your reinforcement of choice (I chose hemp fiber) and break it into manageable chunks.

3. Mix your epoxy resin and hardener according to the instructions.

4. Soak the reinforcement in the epoxy, squeeze out excess resin, and plop it on your joint. Wrap it around and reinforce what needs to be reinforced.

5. Take the polyethylene strips and wrap them tightly around your reinforcement, so that you can squeeze out more excess resin. This will also help keep the surface fairly uniform.

6. Wait. Before the resin sets, but after it's no longer very sticky, take off the polyethylene.

7. Wait.

8. Repeat 1-7 until you are satisfied with the amount of material reinforcing your joints.

Step 7: Build Up the Bike!

Once you're finally done with all the messy stuff, cut the head tube to size and slide that into the bamboo sheath. Glue it in with epoxy. Glue in the BB shell. Don't get anything on the threads, it will be a huge pain to get the actual BB in if you screw up the threads. I used the leftover head tube stock to "shim" (a very very fat shim) the seat tube size down so normal seatposts would fit.

The rest is the same as a normal bike.

Step 8: Ride!

Get on your bike and move your feet in circles. Be happy. Don't die.
Credit me and tell everyone you meet how amazing I am when they ask about your bike.
Hello, Thanks for your tutorial wich helped me a lot! I can't say all I want to say, becausr I can't write very good English... however, I linked some pictures of the bigs steps of the project, hope you enjoy it. Greetings from Switzerland ;)
<p>Fun project. Thanks for the help.</p>
I just finished building my own road bike, take a look:<br> <br> <a href="http://www.cameronbrown.ca/blog/2013/01/how-to-build-a-bamboo-bike-part-1-plannin-things-n-fetchin-stuff/" rel="nofollow">http://www.cameronbrown.ca/blog/2013/01/how-to-build-a-bamboo-bike-part-1-plannin-things-n-fetchin-stuff/ </a><br> <br> <a href="http://www.cameronbrown.ca/blog/2013/01/how-to-build-a-bamboo-bike-part-2-cuttin-things-n-wrapin-it-up/" rel="nofollow">http://www.cameronbrown.ca/blog/2013/01/how-to-build-a-bamboo-bike-part-2-cuttin-things-n-wrapin-it-up/</a>
Fear is innovations worst enemy. Let's be more realistic and more positive before we start telling people that what their doing is a liability. You can be hurt by anything! Doesn't mean you should live life in a bubble of "you could hurt yourself or your fellow innovators" I appreciate this site and i don't want to see anymore of these type of comments posted, it undermines the whole purpose of the site. Please!
Strange way to put it. I have no fear when I wipe out on my mountain bike, but I do acknowledge there will be some damage done (depending on speed and terrain). I recognize there is a risk and keep it in mind, and do not suggest to other people to do things that would likely pose substantial harm. You can't, reasonably, be hurt by anything at equal levels and it is crazy to think that because it is not a 100% safe world that some things need more care and attention than others. I don't care what you don't want to read. It does not undermine at all, it helps keep people thinking about SAFETY so they can assess their skill level before starting a project, have a better result, or spend their time on something else their skill level is more in line with, and most of all live to do another instructable another day. I am not suggesting it is the same type of liability as some, in fact the opposite I was suggesting that at least when people have a frame failure from one made by a professional, they have some recourse to sue, to get at least their medical bills taken care of instead of being bankrupt for life (since interest on medical bills can easily grow faster than a young person's income). Let alone the actual physical harm. REDandroid you seem to take lightly the harm that can come, and I think it is because you don't see a lot of people riding around on alternative material bicycle frames. This is not the same thing as making a rug out of drinking straws, a failure can easily put someone's head under a multi ton vehicle. Never wrote live in a bubble, you are making things up to pretend you have a reasonable position but it is never reasonable to make things up as if you can attribute them to someone who never wrote them. No matter how many times someone says life isn't safe, it is always reasonable for at least the first person to say "hey this is really dangerous people get crippled from far more rugged frames failing every day".
ac-dc I have built a number of bamboo bikes using an instructable as my initial blueprint. I understand your concern for safety but, I have built a road bike, a beach cruiser, and a mountain bike using this method. The mountain bike that I use regularly is able to take big drops and absorb the bumps and crashes that come from regular offroad biking. Bamboo and carbon fiber tow/ or hemp are extremely strong and if used correctly make a beautiful and durable bike. If you were to do your due diligence and research the use of bamboo in the building of bicycle frames you would see that it is a safe alternative to traditional materials. Please do your research before making comments as you are spreading fear that is not based on fact. Any bike frame is capable of failure but, if built correctly bamboo bikes are some of the strongest most vibration dampening bikes I have ever had the pleasure to ride. If you are reasonably mechanically inclined and do the proper research you can build a safe bamboo bike that can handle all of the rigors of their steel, carbon fiber, and aluminum counterparts. It's as simple as that, make sure your joints are strong enough (overbuild them) and that your bamboo is properly heat treated and left to dry for at least a month and you will have a durable bike. Any bike can fail due to poor construction but, there is no inherent danger in using bamboo, hemp, and/or carbon tow to construct your bike. Take your time and don't take any short-cuts and you will have a beautiful bike. It is quite rewarding when people ask where you got your bike and you can tell them &quot;I made it&quot;.
Hey no harm in warning people of potential failures from poorly constructed devices, but it is not cool to completely dismisses an invention as being completely dangerous. That is the interpretation that I got from your initial post. I apologies if I misread your meaning. I'm not the author of the bamboo bike, but 'my' interpretation was that he was not pushing this to be a replacement of your standard rugged aluminum or steel mountain bike, but rather a fun project. I could be wrong... I live in Portland, deemed "bike capital" of the US by some and there are literally thousands of homemade bikes here that are built 'safe'; it's the drivers of cars that you usually have to worry about :) There are the tall bikes where the rider sits 5 or so feet or higher off the ground that I feel are not quite safe. I was hit head-on last winter and taco'd my road bike. I'm sure the bamboo bike would have shattered pretty bad. Take care.
Hey REDandroid- I completely agree with you. ac-dc apparently has a fear of danger, even the slightest danger, and thinks that a fairly reasonable disclaimer is completely unreasonable. I myself couldn't live life without a little danger. It would just be BORING. And if the instructable is suggesting that someone try something risky, then the disclaimer was a good idea and was definitely not "irresponsible" as ac-dc suggested. It may "entice" the viewers to build the bike, but it in no way forces them to build it, and it is still entirely their choice to build a bike that is a little more risky than a welded aluminum one. So my suggestion to ac-dc: Back off with your arguments, I bet you that at least more than half of Instructables would readily disagree with your ridiculous statements.
How dare you suggest I should not voice my opinion because you don't like or agree with it. Did it occur to you that I will give your opinions no more respect than you have mine? Do you even understand why we live in such litigious times? Because people act without concern of the consequences then blame someone else!! They make statements like "blah blah blah that person has fear of danger" but you overlook something, if I choose not to build a bamboo bike there is no need for me to write anything about it here, I could just let Darwinism finish off the weaker links. As I had written already, indeed I do not control what choices someone makes including whether to build this or not, I only offered my opinion and you act like a spoiled child because it differs with your own. Grow up and accept we are not censoring people they are entitled to disagree and it should always be stressed to err on the side of caution. People really do, do dumb things and the reason eve more don't is because all the way through life we have little reminders from others that "hey this may be dangerous, think about what you are doing". It all comes back to central issue in many types of projects, if you have to be told how to do it instead of having the experience and intelligence to do it without instruction, you probably aren't fit to do it. When someone offers to help, how much can they really do so? Can they inspect your bamboo bike over the internet? Can they catch you if the frame collapses next to a car going 50MPH? Will they care that you have "no fear" (Nonsense! You hide behind a keyboard when you'd ever act this way IRL) if they wreck? I never claimed that the act of disclaiming was irresponsible, the irresponsible part is acting as though that is enough. Someone could easily follow instructions to the best of their ability and it still woudn't be enough, mere text readings "blah danger I no responsible" doesn't drill home that there is a reason average people aren't grabbing materials to DIY modes of transportation commonly used on public roads alongside dangerous vehicles. There is a difference between being afraid of something and acknowledging a risk. I knew the difference going in but you would LOVE to twist things so you can pretend to be more reasonable. What's the best case scenario if you build a working bamboo bike? you get to ride it same as you could've the original frame or any new bike. What's the worst? Is the worst really worth the risk vs payoff? Really? Have you built this several ways including wrong so you know where the issues lie? Or are you just upset that some things really shouldn't be tried at home? Being responsible isn't about your own safety, it's about how your actions impact others. Throwing around challenges like "fear of danger" is irresponsible. If bamboo were an equally good frame material, then one professionally made would seriously compete with other materials in the marketplace. I suppose you can't even accept this fundamental truth and it far precedes making a frame out of the best materials mankind uses.
Sorry if I made you feel as though I was saying you couldn't voice your opinion, but I still disagree. I think pretty much everyone else here disagrees with what you're saying. And I am not "throwing around challenges like 'fear of danger'" - you may not realize that you come off as someone who is afraid of risk and dangerous activities - I'm just saying it how I see it, maybe you don't intend to, but you do come off as a safe freak and that's not what Instructables is about.
I think we are beating a dead horse. All that needed to be said was, we are only offerining input and then each person decides what to do. I feel this is a strange reaction sometimes, if someone disagrees everyone thinks they "insist" it be their way but I do not. It is a forum where obviously we all add a little bit to think about. It's just about more info, if you or I choose risk, so be it, but let it be a fullly informed choice.
Do you know if carbon fiber fabric strips would work as well? I can't find a local source of carbon fiber tow. I'm in Singapore right now, and finding the materials is proving a little difficult.
I just did one using twine and got very neat and strong results. Basically just bathed the twine in fiberglass and wrapped it around the joints. <br />
Beautiful work!&nbsp; So how is this bike holding up now?&nbsp;&nbsp;Any concerns about durability?&nbsp; It seems like that would be the primary drawback to bamboo frames<br />
Looks great.&nbsp; Everyone thinking about building a bamboo bike should look at <a href="http://bamboobike.wordpress.com/" rel="nofollow">http://bamboobike.wordpress.com/</a><br /> <br /> There is plenty of detail on how to choose bamboo, how to make the hemp and epoxy joints (like calfee), how to choose bottom brakets, specifics about working with aluminum and steel, how to use an awesome online mitering pattern tool etc etc.&nbsp; Check it out.&nbsp; <br />
Nice, thanks for the link--is that a PVC&nbsp;frame jig in that pic?
Yep PVC, but there is more detail on at the site. <br />
My bamboo frame is cool. But it flexes soo much when I stand on one pedal or even torque the handlebars. Does your bike do this too? <br /> <br /> Anyone have an idea as to how to reduce this flex?<br />
Indeed excellent. This is one of the few real &quot;practical&quot; applications I've seen in green thinking. Now that's for sure renewable energy right there.<br/><br/>Though, the resin could have been furan (aka furane or furfuran) instead of epoxy. The metal pieces I understand, although there's a wood called Pockenholts (scientific name is Guaiacum officinale) which is one of the hardest woods there is. It's actually used as bearing brckets in the local steel plant. =) Ebony is hard enough as well to work as bearing surfaces, though it's pain i a** to work these woods.<br/><br/>Nonetheless, excellent DIY project. 5 of 5 stars from me.<br/>
Wow, I was wondering if there were any alternatives to the epoxy and the metal and you show up and tell me exactly what they are! Thanks! However I did a quick google, and it appears that furan is very hard to work with, "a colorless, flammable, highly volatile liquid with a boiling point close to room temperature" and "toxic and may be carcinogenic". Not to say epoxy isn't carcinogenic, but it is fairly stable at room temperature. Do you know how to work with furan as a replacement for epoxy resin? Also, the trees that yield extremely hard wood appear to be mostly endangered... so perhaps some good old steel isn't so bad? What do you think?
I used some kind of non-toxic carpentry glue and hemp string. The glue was about half the price of epoxy to boot. <br /> <br /> A chemical engineer told me that the two components of epoxy are toxic on their own but fairly safe once mixed and hardened. <br /> <br /> My problem is lateral flex. I have a lot of torsion around the bottom bracket when I stand on one pedal. Is this normal? Can anyone think of a design that would address torsion? <br />
I really don't understand about that metal thing... but hey if thats such bad thing for the environment maybe next time you can forge all the metal parts out of melting tin cans by the power of the sun? a magnifying glass maybe?
Making steel is a very dirty process, involving large quantities of energy and pollution (You ever been to a steel plant?) and making metals such as aluminum is even more dirty and energy consuming. The woods I suggested here are as hard (and sometimes harder) than steel, lighter than steel and they grow by thenselves. Is that what you ment?
yes exactly what I mean... sometimes under the great wheel of the green movement people don't actually make any sense any more.... from the look of this project it's impossible to replace all the metal part with whatever wood you are talking about. even if you could how much more time and skill would require for this project? let alone the tools that'd require for it...unless if there are company out there thats already selling the ready made parts out of wood. it's just seems really impractical I think it'd be way too expensive it'd most likely triple or quadruple the price for this project. It just seems really unrealistic to think that it's possible for our society to live with out metal. Unlike plastic, most metal are harmless to the environment and it's extremely easy to recycle. I am all for cutting down the energy consumtion for every product we make, but you also have to keep in mind that there is always the practical side that we have to think about.... after all the end product are used by people. if it has to come to a point that people can no longer afford it then we are just wasting our time.
Any carpenter or cabinetmaker can manufacture these parts, and there are tools and machines for it as well....
Actually...<br/><br/>I used to work in a plastics factory (mostly fiberglass construction for industry applications) and we also worked with a development project concerning Furan as resin in an environment project. As this project is largely classified as of yet, I can only tell you basically what I've said so far, but Furan IS in the works to be commercially available as a &quot;green&quot; option to polyester and epoxi resins.<br/><br/>The one thing with it as far as I am concerned, is that it gets a brownish color, and looks like crap unless it's painted or some such. And it smells rancid! =P The styrene fumes from the polyester resins are perfume compared.<br/><br/>Anyways. Furan, as a pure compound, is certainly what you describe, but it is a working resin to date, although hard to come by and fairly expensive as well. Give it a few years though....<br/>
Cool! Even more reason to be excited about the future!
&nbsp;Hi, first off this instructional inspired me, im now starting to build one. but i have just one question for you. how did you get the bottom bracket shell in. did you use a glue/resin? thanks. ill be using carbon tow (string)
wats OSH?
That would be Orchard Supply Hardware, <cite>www.<b>osh</b>.com/ <br /> </cite>
Hi,<br /> I'm planning on building &nbsp;one of these babies, and i was just wondering, how deep does your seatpost 'shim' go? is that what you are going to put the clamp on?&nbsp;<br /> thanks,&nbsp;<br /> Adie
coolest thing ever,&nbsp; i have seen on the green channel (year right green) when they used to still show stuff that was actually interesting when it first started about a company that creates bamboo bikes, but that was like for $7000, that totally turned me off to the idea, but with these easy steps i know i can do one myself, but i will probably do a BMX frame since i prefer those kind of bikes, thanks for the post, when end up doing it i will definitely link it to yours,&nbsp; thanks for the inspiration and for being green (minus the chemical epoxy, but i understand) :)<br />
im thinking that you might have had a nice stronger finish if you had used a bit more epoxy that sanded it down a little so it is nice and smooth then if you want you have have added a varnish of some sort
the resin in a composite material has no strengthening properties on its own. extra resin is just extra weight(though you dont want to starve the fibers of resin). you can sand, but sanding any further than the surface of the fibers, weakens the joint because the strength of these composites comes from the long fibers. if you sand into the fibers, you shorten them.<br />
"get your reinforcement of choice (I chose hemp fiber) and break it into manageable chunks." did you consider just taking a spool of hemp, making an initial knot, and keep winding tight, and brushing on epoxy as you went? I assume you used a whole spool of thread for the bike (do you know weight of hemp), and I assume that its much easier to work with than fiber/carbon sheets?
people use spools of carbon threads, but not cloth, as far as i know<br />
On a similar project I saw, the hemp joints were done a little larger than needed and then sanded down after they cured. This was a little more streamlined and also the look was just fantastic. Give it a try and see how it works. Great project.
A Zen-bike!! Never-mind 'be one with nature', you're gonna be one with the pavement! lol Very cool idea though.
Just a question about the &quot;test&quot; weight. Wouldn't velocity increase your actual weight through force/speed? I wouldn't know how to accurately figure that, something along the lines of weight x speed = force/perceived weight at contact point. I'm showing my calculative ignorance here but, just wonder how that all plays out? Great idea though and looks like a fun ride.<br/>
I've used a flexural strength testing apparatus (a machine that does pretty much what you were trying with the bricks) on different frame materials, including bamboo aluminum and steel. The machine wasn't calibrated, so the readouts were essentially unitless, however the results of each material could be compared with each other. The bamboo withstood the most amount of force out of all of the materials, which was impressive. It also sprung back into shape when the weight was removed (unlike the other materials). So not only would I not worry about the crash safety of bamboo, but I'd actually prefer it over the other materials. It deserves way more credit than most people give it.<br/>And as an aside, acceleration does not increase force. Rather force <em>causes</em> acceleration. Further if the force is constant the acceleration will be constant, not increasing. But if you're worried about crashes you should actually be looking at inertia, and more specifically inelastic collisions.<br/>
Depends how the seat is, and the g forces wouldn't be enough to increase his weight by all those bricks.
When moving on a bike, your only acceleration is parallel to the ground (unless you hit a curb or a pothole), so I doubt that the perceived weight/normal force increases. I'm not so hot on the physics either.
I was thinking in reference to impacts (which I apologize for not making clear). Potholes (big and small) and other road imperfections might cause quite a beating on the joints.
velocity increases I rather than F, acceleration increases F. So initially you will have an increase in F but in a static system you have the exact same F as you do in any other static state. The only change you should really worry about is when your acceleration is sharp. That could cause problems.
What type of hemp fibre did you get?
You have got to be kidding. If you are on this site at all you must know that most anything home made will have risks. I think this Instructable is great. There are now commercial bike builders ( saw one on Green Network TV) using bamboo. They are very expensive. The techniques they used were the same. Please give this guy the respect he deserves . And, if you don't feel safe building one... DON'T!
If this is your philosophy of DIY, you will be writing a lot of these 'shame on you' comments. There are many, many dangerous things posted on Instructables. We would hope that individuals are smart enough to know their limitations. David, who will not be building a 7 foot Tesla coil or a Leyden jar out of a 3 foot cylindrical acrylic aquarium.
... and I am totally in support of warning on each and every one of those Instructables. Not just the token gesture disclaimer of "I'm not responsible", but that people should take a good hard look at the possible outcome if things don't go according to plans. Just because you "can" do something, doesn't necessarily mean you "should". I am going to generalize that there are very good odds that a substantial % of people DIY building a bamboo bike frame will have it fail on them. Possibly even the author, I don't want him injured either. Individuals that don't have limitations that would pose a risk don't generally need to be told how to do something like this. As the old saying goes, "If you have to ask...". Now I have already written more than I ever intended to, but some clarification was in order. IMO, not every project is as reasonable as the next one, I think deep down you would agree that children and young adults feel a little more invincible than they really are, as accident rates tend to show statistically.
ac-dc, I'm not here to flame you. I think your responses are well reasoned, despite some of the angry responses you've received. Personally, I am glad you wrote in with your initial comment. It raises a question worth debate. So the question is: As a maker and writer of an Instructable, what is your responsibility to keep your readers safe? How far does your culpability extend?
It is not your responsibility alone, that is why we should welcome all input from posters as to the potential risks, and ways to test and ensure as much safety as possible. Until that happens, it remains more and more of a risk. I suppose we could make automobile frames out of bamboo too, but that I would even more strongly encourage people to pause and think about before doing it. Contrary to some posters here I cannot agree that because something in life has a risk we can simple sweep aside though of risks, especially when not all risks are truely equal. I do however feel this project should not be posed to people who cannot compare the strength of the new frame against the original and find it at least as strong, keeping in mind bicycle frames are generally, per type/purpose of bike, as light as they can be and still meet a minimum durability level. One last thought. In more and more industrialized areas, there tends to be more and more automobile traffic. Places where it is more common to have a homemade bamboo bike, you are less likely to have as many very high speed vehicles around to make a mistake a terrible one.

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More by xman:Mobius Zipper Bamboo Bike Frame. 
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