Contour

Alright after going through the previous threads I decided to make my own and maybe try to consolidate a the information into one place.

Just to preface, I'm not an experienced cyclist let alone frame builder. So anything that I may suggest is just my opinion. This thread is also to document my build process so others can use it for reference.

My goal is to build a bamboo frame and I think I've got a pretty good understanding but there are some parts that I could use some clarification. Firstly the seat post, is it just slid straight into the bamboo with the locking collar at the top?

Also for the bottom bracket is it best to get a lugless and weld or attach some mounts for the bamboo to slide onto just for increased rigidity. If this is the case what would the best method for this be? Or would it be easier to just chop an old frame up?

Also for the rear triangle are there any good methods for alignment? I plan to build a cheap jig (maybe something like this https://www.instructables.com/id/Almo...rame-building/ ).

Resources: (will be updated as the thread progresses)
https://www.instructables.com/id/Bamboo-Bike-Frame/
https://www.instructables.com/id/How-...amboo-Bicycle/
https://www.instructables.com/id/How-...cycle-or-bike/
https://www.instructables.com/id/How-...ome-and-a-bam/
https://www.bikeforums.net/showthread...ghlight=bamboo

Contour

Alright I'm going to reserve this first post and update it with progress, tests, and results.


From Plant to product:






These pieces were just practice so I could get used to the heat treating process.
At my school I have access to a large machine (the name slips my mind at the moment) that can apply a lot of force but measure it very accurately. I plan on using several methods of heat treating and messing with the bamboo to find the ideal methods. I'll try adding some foam as BME suggests and test whether it makes a difference and if so by how much. I'll try heating, sanding, reheating. Just heating, then letting it dry out in an oven and then hitting it with the flame.

Also to heat treat it all I did was take a plumbers torch with mapp gas and go back and forth over the bamboo until it started to darken. After the testing I'll figure out which method works best and try and repeat the results.

NoReg

There is some question over whether heat treating is actually anything more than a method to remove excess moisture. Invariably the material will return to the ambient level, but heat treating either removes excess moisture above ambient, from growth or storage, or it lowers the moisture below ambient to a more favourable range, depending on the ambient range. Flaming by itself is just rough and ready heating. People like it the look also.

I make bamboo rods but haven't made a bike. If it was me, I would get an aluminum BB and use carbon fiber to make the connections, or glass. Not sure this is an app where the benefits of carbon are required, at least for initial experiments. Carbon is always lighter, but since it isn't the stuff the bike is to be built of, it may not be necesarry. Some of that Rutan tow that Aircraft spruce sells might come in handy.

Old Town

Contour I applaud your craziness. I love this thing you are trying. I've made a few longbows out of Tonkin Cane which is a type of bamboo. In my work, however, it was cut into strips and then I made a press and used epoxy to bind everything together. Using the whole plant as a "tube" may require you bind the ends of the bamboo (like end of seat post) with some kind of thread to keep the bamboo from splitting. It can be done in a decorative way. I'll keep an eye on this thread. Can't wait to see what happens. Good luck.

Allen

The TOW is much easier to deal with than cloth in my experience.
The heat treating is to remove excess moisture and to help prevent splitting as I understand.
I smoked my bamboo, supposedly it helps keep fungus, mold, and bugs down.

Allen

With the bottom bracket you can get away with just scoring the surface so the glue/resin has something to grab ahold of.

Wrapping the chain stays in carbon helps to stiffen the frame.

Contour

Thanks for the suggestions an comments everybody!

Allen, how has the smoking worked out for you? Did you notice an improvement in protection from the treated and untreated pieces? I've been looking around for treatments for bamboo to ensure it's longevity but I have yet to see anything consistent. Some sources say let it soak in water for three months, others say soaking in boron solution, along with other methods. I'm curious as to how the compare with each other and will try to test different methods. However these are long term effects so it's hard to test for them.

Also have you had any issues with crank arm clearance with the bamboo chain stays?

Also, if anyone has any resources on curing carbon fiber (clothe or tow). Also what kind of epoxies are used with the hemp and sisal (having trouble finding a source for this, if anyone has one let me know) fibers. Does the curing matter based on the material, epoxy, or is it a combination?

Old Town

Contour you refer to curing carbon fiber. In all my years of building race kayaks (that's what I did for work) with carbon fiber cloth, I never heard of a person paying attention to moisture content. The stuff comes in a roll from the factory. It takes on whatever the relative humidity of the work shop is (in time). I would not worry about curing. Unless you are talking about the curing of the epoxy used to bind the fibers. Then you should just read the manufacturers literature. For any natural fiber like wood, sisal, hemp, you can not go far wrong with WEST SYSTEMS epoxy. It's formulated for wood boats. There are other equally good products available however. In time you will find there is very little magic in working with composites, natural or man made.

Contour

Doesn't the carbon need certain tempatures to cure, that was one thing I was concerned about, or is it just all resin's/epoxies in general? And is there any specific West Systems epoxy that you would recommend?

Old Town

No on the carbon fiber. It is inert. Use it like it were wood or fiberglass. The only thing that is important is the kind of binder (resin) you use. It must me compatible with the carbon format (linear or fabric) and it should be allowed to set (cure) at the manufacturer's recommended temperature. Some do need an oven and higher temperatures. But most modern epoxies set at room temperature just fine. The list of agents is too long for me to type here. West Systems will work with all carbon products even though it's most often used in wood work and wooden boats.

It's been a few years since I used WEST SYSTEMS, but when I did, they only had one base epoxy with several different catalysts for different ambient temperature ranges. One was for temps around 75 F, another was called "Tropical" and it was a slower hardening catalyst for use in the tropics, or for a longer pot time. I think there was one other but I can't remember its purpose. A guy could do all that was needed to be done with the standard hardner and the slower "Tropical".

It's always a good idea when playing with resins for the first time to make up a test batch and get a feel for how it "sets up". Spread some on a little bit of carbon fiber or glass cloth. Glue some pieces of wood together with it. Thicken some with glass beads or micro-fibers. Get a feel for it. Making things out of wood and fiberglass is addictive.

P.S. Standard WEST SYSTEMS hardener has about a ten minute pot life. Less if it is above 80 F. Tropical extends the pot life to about 2 hours at 80 F. Both hardners set up faster as the temp goes up. At 95 F and above I used to leave the shop and go drink beer instead. Everything happens too fast.

Contour

May be a silly question but what is the difference in pot life and working time? Also just another general question, do you let the previous layer completely cure then add the next layer? Or is the second layer applied almost immediately after. For the linear how exactly would it work, just don't overlap on the same layer (if it needs to cure before applying the next layer)? Also for vacuum bagging is the primary purpose to get out the excess resin for weight purposes or strength?

Old Town

Pot time, working time, pretty much the same thing. Remember mixed epoxy in a container will get hot fast. That same epoxy spread out cannot develop heat as fast. So to extend pot or working time, spread the stuff on a surface and take it from there like a painter uses a palette. Make a practice batch and pour some in a dixie cup. Spread the rest on a paper pie plate. See how they cure at different rates. The cup will even start to smoke. (It's not real smoke) When I said 10 minute pot life, I meant the lump of epoxy in the dixie cup. That's the "worse case" scenerio. Same is true for tropical hardener. Maybe 2 hours in the dixie cup and could be 4-8 hours spread out.

You can add layers of glass or CF as soon as the first layer is set up. No need to sand between layers. This will only result in very clogged sandpaper as the epoxy is firm but not really stone-like. No problem with adhesion between layers. But do not go more than 48 hours between layers with WEST SYSTEMS or you will have to first wash the surface and then sand. The reason being the curing epoxy releases a chemical called "amines". I could have the spelling wrong and really don't know what the hell amines are. All I know is that they form a water-soluable top layer that is greasy to the touch. Almost like someone rubbed baby oil on the surface. And it has a strong chemical smell. This greasy layer will mess up further layers if you do not remove it with soapy water and then roughen the surface with course sandpaper. This should never be a problem if you simply do all your layup work in rapid succession.

Linear stands can be arrainged at your whim. It's the epoxy and how long you take between applications as mentioned above that is important. You always want previous work to stick to later work. If you have to wait long periods between epoxy application just wash the old work and sand. It's those damn amines that slowly work out of the epoxy you have to be aware of. If the thing you are making is done all in one shot, as in vaccum bagging, amines are a moot point. (unless you plan to paint the surface - then treat painting like another layer of epoxy: wait 3 days, wash, sand, paint)

You are exactly correct about vaccum bagging. It's the best way to control the exact amount of resin going into a known area of composite material like glass or CF. A good layup man working by hand can equal the quality of a vaccum bagged product. But there are damn few good layup men around. (Now for some shameless self-promotion) I was the first person to use vaccum bagging in commercial kayak construction in the US and probably the world. That was in 1978 about 5 years ahead of most other makers. I went to VBagging because I could not find workers who could do hand layup work of suitable quality. At first I held my nose at the notion, but in time came to realize what a good thing it is. The technique was taught to me by an engineer I hired from the aircraft industry. I did not invent VBagging by any means.

Hope this in some way helps.

Contour

That is very helpful. Would it be worth it, at least in your experience to build a small vacuum bagger that could be fit around the joints?

Also for linear strands is it best to alternate the directions layer by layer, or at least to have the fibers going both ways?

Old Town

For what you are doing bagging would serve no real purpose. The little joints are easy to fuss with and not over-epoxy. Bagging works best with larger products where total finished weight is important. If you use too much epoxy on one joint it means (maybe) a quarter ounce. No big deal.

It's hard for me to advise how you should set stands of CF without seeing the application. I suggest you make a couple of test joints out of scrap bamboo and test them yourself. That is half the fun of making anything anyway. Do remember that carbon strands (unlike cloth) do not bend, they break all at once. This can be very exciting should it happen on the prototype at 30 mph. Make test pieces first.

Truth be told, 98% of my CF work involved fabric in boat hulls. The only strand work I did was in wing paddles. It was simple work and I can't really say I learned much. I'm sure there are guys on the forum who have done more with carbon in linear form than me. There might even be good information at the library or on the internet.

Do not listen to people who say what you are doing will not work. The world needs nuts like you. Push on, and if it doesn't work out, no big deal. As a kid I started to make a submarine out of oil drums. The cops stopped me at the launch site. I still regret not having completed the project. Carry on, and down periscope!

Allen

I use West Systems. One squirt from jar A one from jar B. Can't beat it.

I got my carbon through Aircraft Spruce and I don't remember where I bought my hemp fiber--I just searched for "hemp fiber" and picked one.

The bamboo I bought was already dried, I'm sorry but I don't know if the smoking process did anything but change the color a bit and made the wood smell good.
When I bought my wood I bought two different verities of bamboo, Black and Moso.
Some of the black bamboo split during the smoking process. The rest has been stable for several years now.
I did not smoke the Moso and it split (with sudden and loud pops) over the next two years just sitting in my shop.
Of the 80 feet of Moso I originally purchased, I have maybe 12 feet of usable wood. I won't buy moso again.

nwmtnbkr

Too bad you're on the opposite coast from the Bamboo Bike Studio. They have a 2-day course that teaches you the basics of building bamboo bikes. (They are doing good things in conjunction with Columbia University's Bamboo Bike Project--attempting to help establish factories to build bamboo bikes in a number of third world countries.) Since you're a student, maybe if you contact them, the Bamboo Bike Studio can give you some pointers via e-mail. Here's a link to their web page, which has contact info. https://bamboobikestudio.com/go/home Good luck, your project sounds interesting. This is a thread I'll keep track of.

Old Town

I had no idea that this had been done. I'll have to Google Bamboo Bike Studio. People who think along such odd lines are the best.

ChiapasFixed

i built three frames out of bamboo back in 2007
one broke due to undetected worm infestation
the other two are doing fine!
i had a couple threads about them and other's 'boo bikes here

Old Town

ChiapasFixed: Coolest bike photos I've ever seen. Do the bikes ride soft? There must be some flex.

ChiapasFixed

surprisingly little flex, similar to a steel frame but with the vibration dampening of a carbon one.
i understand the rear triangle can be stiffened further by wrapping the chainstays in carbon cloth.
I have not found this necessary, but I dont seriously race. the fixie is plenty fast, though. it is modeled after an Eddy Merckx corsa extra.

PhilNYC

Also check out Sol Cycles in Princeton, NJ...

https://www.solcycles.com

Old Town

Thanks for the link. If someone had told me you could make a working bike out of bamboo and it would hold together over the first lumpy road, I would not have believed it. Untill I joined this forum and found this link, I had never heard of bikes made out of any kind of wood let alone a grass. (bamboo)

PhilNYC

Here's another one...Calfee Design, a longtime top maker of carbon bikes (I believe they made Greg Lemond's Team Z bikes), offers a bamboo bike. They also have some kind of work they are supporting in Africa to make cheaper bamboo bikes:

https://www.calfeedesign.com/

PhilNYC

As far as other wood-frame bikes, here's one I found:

https://www.renovobikes.com/

Frames look absolutely beautiful, although they are not as "green" as bamboo. I don't think they are as strong/light as bamboo either...

Allen

Calfee got the bamboo thing going again (it's been around as a frame material since the beginning of cycling).

Calfee inspired Brano Meres, and he built a bamboo mountain bike. Brano's website has inspired a lot of hobbyist builders.

https://www.bmeres.com/bambooframe.htm