ultraman6970

what the topic says...

thanks...

ps: the link at sheldon regarding this topic sisnt working..

Bob S.

Since no one has bitten on this thread, I will give it a stab.

I don't see why it can't be done. It would be an easy task for those with high end composite laminating experience & skills. However, I suspect that it is a rare individual who has the requisite skills, knowledge, shop space, material access, time & motivation to undertake the task. Much the same as it is a rare individual who builds his own aluminum, steel or Ti frame. Another example & similar task are those in the Experimental Airplane Owners who build their own carbon planes. There as some, but not many, and most of those are kits.

Perhaps there is a market for kit bikes??? Bob

On edit: Thinking about it, I don’t have any interest in a bike from scratch, but a high end carbon might be intriguing.

Jonny B

Thought about it. The actual build process (laying up) isn't really that hard, but designing the frame (and deciding where to put what type of carbon cloth, and in what direction) and making a foam core or mould are very difficult and time-consuming. Also, you'll have no precident for how strong it will be (whereas a steel builder will now that, as long as his or her brazing is up to scratch, the lugs and tubes will make a good bike), so some form of testing will need to be undertaken (possibly a destructive test, like the guy on Sheldon's site). And bare in mind that it's gonna cost a bit too, for what Sheldon's pal spent you could have a top-spec 'normal' bike (about $2000 I think).

But if you're willing and able to spend a lot of time and money making things like moulds and jigs, that you'll probably only use once or twice and no-one will ever fully appriciate, the possibilities are endless. Just think how many weird and wonderful carbon frames there are out there, from crazy monocoques like the Lotus Sport bike, to bonded tubular ones like the Colnago C50, to the step-through that Sheldon's guy made. Just keep an open mind about design, and you could end up with a bike unlike any other.

potus

there's this one:

https://bikelugs.com/columbus_mecano.pdf

sestivers

My team won my college's senior-year design competition with a composite hockey stick. A hockey stick is more complex than many might think, but it is immeasurably more simple than a bicycle. It took most of a semester of work for our team to make that thing. We also had access to FEA programs and a shop to build it.

If you want to feel safe on your bike, I think you'd need a good handle on the FEA stuff.

ultraman6970

HI again thanks.. about that columbus kit its nice but they dont have a the track option to start with... and well... i dont have 2 grands to spend on it... regarding material it is posible find at ebay carbon cloth in big pieces and cheap ... Oh just like a tip for everybody in here.. thrre is a guy in eastern europe that built a MB frame with Bamboo sticks... looks like a nice proyect.. besides he did his own carbon frame too and looks like easier than work with glass fiber that is a pain in the ass... if u have no clue wtf r u doing heheh (me! hehe)

I wish I could see the sheldon's web page carbon bike proyect, but the link is broken since who knows when...

Doing some research I found out a few things.. well the core is a pain in the ass but using styrofoam RODS our life its a lot simplier, built a low budget frame jig isnt hard. I wish we could share info about it. I found a guy who sells a set of plans for a carbon recumbet (or whatever the spell it is) bike.

Well as far as I see this, the secret is building a nice foam core, if that core is straight the result is an straight frame, depending on the design a frame jig isnt needed at all. SO anybody knows how to use autocad or something? hehehe...

Well I would like to make my own track bike in carbon.. and doesnt look so hard after all, even apply preasure to the fiber to get it really compacted its easy to do using shrinking tape... but well maybe im only dreaming

thanks.. anybody wants to share ideas?

Ultra

ultraman6970

Fea********************

Nessism

Check out this guys web site:
https://homepage.mac.com/w.rentschler/PhotoAlbum71.html

Frames are built with the Dedacciai DCS kit - available from bringheli.com for about $600. Some sort of fixture is highly recommended to hold everything in place while drying.

Enjoy.

Ed

sestivers

FEA = Finite Element Analysis. It evaluates the strain on any point of the frame after you place all the loads on it. From this, you determine which places need thicker/more layers of carbon, different fiber direction, etc.

ultraman6970

Thanks

khuon

This guy is my hero. Not only has he made himself a homemade carbon fibre MTB frame, seatpost, saddle, hubs and headset but also a composite CF/bamboo frame as well. Check out his axle-less hub with carbon fibre bits!

khuon

Note that if your shapes/mesh is not complex or you're not incredibly picky then you can utilise a standard spreadsheet program such as Excel (I once used Lotus123) as a poor-man's FEA program. I even validated my node model results using ANSYS and everything was close enough... at least within what one would expect of engineering tolerances. Obviously a very large and complex mesh would be a pain to set up in a spreadsheet.

ultraman6970

thats the guy i was talking about.. i wrote him but he hasnt asnwer yet...! awesome job...

potus

here's another one:
https://www.fixedgeargallery.com/2005/july/SethDavis.htm

Bob S.

The trick here is the experience & ability of the laminator. Quality control & technique important. Without it, the laminate part's physically properties can run all over the board. A poor lay-up or resin cure problem will never meet the needed physical properties. But, to the experienced fabricator, these are second nature.

If one goes with traditional straight tube geometry, the molds are easy, assuming that you are willing to go a male plug, wet contact lay-up route. Simply use fluorescent light tubes as the mould. Put your mould release agent on the light surface, do your lay-up, once the part has cured, give the part a sharp tad to break the light tube, & presto, finished hollow part. If desired, one could use this with other curved light tubes if their shape & size fits your needed radius & size.

ON EDIT: As for the fiber orientation, my first instinct w/o any reasearch would be: A triaxial layup of 0, +45, -45 deg. relitive to the frame C/L. (strength along the length & tortionally). I doubt that much hoop strength is needed. For a bi-axial, I think +/-45 deg. I would be worried about not having the 0 deg. layup. I thing I will start looking @ the carbon frames to see what is commonly used.

Thanks for the link on the kit bike. Bob

meb

I'm building a homemade carbon framed monotube bent.

John Climaldi (aka Portland John over at Bentrider Online) came up with the idea of using carbon sailboard masts for monotube recumbents and then carbon wrapping at the frame junctures.
https://homepage.mac.com/john4bho/Menu3.html
It looks as if he has removed the construction details of his bike, unfortunate since it was very impressive.

I've acquired a sailboard mast and will saw cut the mast and lug the frame tubes together.
I think lugs are a proven lower tech solution readily facilitating repair, modification, and assembly better for the inexperienced composite worker.

ultraman6970

HI thanks ...

well u can get carbon fiber tubes in the market so far...

Thanks hope we could talk about your proyect since we r in the same area...

Ultra.

Serpico

guy says he works for Parlee and made it in the shop

doesn't sound like "home made carbon" to me

(but cool nonetheless)

ultraman6970

Hi again I got an answer from Brano the guy that did the carbon and bamboo frames and he says that both are ok so far today...

...

Jake B

Hey Ultra-where do you buy the tubes?

Thanks,
Jake

bharnett

I have made several carbon frames since 2000 my first was a pivotless rear suspention mountain bike.
Here's a link to see some of them, I build them for a hobby.
https://www.harnettcycles.com/harnettcycles.html

Brian

Cyclist0094

Nice bikes! I love the tandem!

meb

Pivotless?

Is this a Moots-like suspension in carbon?

If so, how does the carbon hold up under the flexing?

bharnett

It is only similar to moots in that it has a flex plate behind the bottom bracket attaching the chainstays.
I made a carbon leaf spring attaching the seat stays to the frame to keep the frame from having any torsional twisting, that works very well and there is a elastomer damper attached to dampen the rebound effect.
The first carbon bike was my mountain bike the suspension is fine after 5 years of riding singletrack.
Carbon has an infinite fatigue life as long as it is designed within its limits.

Kustomz

bharnett,
Interesting design on the rear suspension! Thanks for sharing with us.

If you don't mind, did you use alu or ti for the metal inserts, such as dropouts, bb, and head cups. Also, did you make any special prep to the metal first such as liquid coatings. This would all be in reference to possible galvanic reaction between the carbon and metals, that I have read about elsewhere.

And then if you are really willing to share, how about some info on the main structure. Is your material laid up over a foam core, or have you bonded to shells together.

Thanks again, great stuff.