Carbon Fiber?

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Hmm.... Plenty of medical insurance available? ;)
I think you will find the answer is "No, not as like-for-like sizes and dimensions".
People do indeed build CF trikes but the requirements of the CF members are very different from "16 Gauge".
 

Radical Brad

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The answer is absolutely not.
You cannot make any of my plans from carbon fibre or even aluminum.
Both will fail completely and without warning.
Neither material is forgiving at all.

Having said that, feel free to give it a try, and adjust as necessary!

Brad
 

Radical Brad

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It sure is.
And you will need to be a superman of knowledge in order to make it hold up.
There is LOT more to it than something simple like normal fiberglass.

You should follow your passion, but do let me say that there is nothing here that will aid you in that goal.
No design here is suitable, and there is almost no info on carbon or aluminum designing here.

Perhaps your trials, failures, and wins will be the first?

Brad
 
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Looking the plans over I can see how you rely on the properties of steel for more than strength but flexibility etc. so even if a carbon tube had the necessary strength I can see how it wouldn’t have the other necessary properties

Seems you rely on a specific amount of chassis flexibility as a form of suspension that carbon fiber would not have

I will stick with the known as opposed to trying the unknown
 

Radical Brad

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Yes, a mono boom frame of steel is great for strength and has some predictable flex, making it the perfect choice.
With aluminum or carbon, a mono boom frame is actually the worst case scenario.

Brad
 
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Carbon fibre diamond frame bikes have been around a while but they use almost perfect triangulation to keep all forces along the length of tubes. A recumbent uses a frame design that places many forces perpendicular to the length making it a serious issue. Utilising full suspension would mitigate that to some degree. How much I do not know. I would expect any failure to be sudden and dramatic, not to mention painful. There are a few high end carbon recumbents such as the NOCOM but these use a monocoque design with massive inherent strength that is exceeding difficult to replicate, explaining why they are high end.
 
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I think if I was an engineer I could design a simple truss frame from carbon fiber tubes that would work but, alas, I am not an engineer. This is a simple truss from 1" square tubes carrying over 2,800 pounds but then again some of those balsa wood truss designs carry a amazing amount of weight. I know it is a different application but then again essentially a diamond bike frame is simply a different type of truss.

https://dragonplate.com/carbon-fiber-truss
 
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A truss would distribute forces well but making one small enough to be practical would be difficult. I did consider carbon for my current project - a fat tyred SWB recumbent bike using round tube with internal steel joints in a similar but reverse manner to how the old brazed frames used to be made but decided to stick to steel as I could find very few examples of what I was considering.
 
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recumbents.com has information on building carbon composite bikes and trikes, good reading. Mono tube bikes and trikes need large diameter (50-65mm)and thicker wall (2mm or more) tubes. Read the information on recumbents.com before building carbon bikes!
 

Radical Brad

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The cool "Ground Hugger" by JQ Riley was also a DIY carbon frame, and I once considered building one.
But to this day I have yet to see any posted example at all (anywhere) of someone making one.

Brad
 
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And for goodness sake chaps and chapesses, its Fibre not Fiber. :ROFLMAO:
Like its Tyre not Tire (because we are all tired of the mis-spelling) ;)
:p:p:p
 
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I was thinking about making a trike out of pvc pipe them wrapping it in carbon fiber tape. I found this site that sells carbon fiber tubes, squares, and fittings that maybe cheaper. The site is https://dragonplate.com
Enjoy and let us know if it works.
 
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Carbon fiber is strong, but you can't replace steel for carbon fiber. You can copy a design, but you need to change things like diamer, thickness and joints.
As you put the model in a cad program, than you can see where it flexes and what the weak points are.
Look also ad oval shapes for surten parts.
As you don't put it in a cad program, make than first some test parts so you can check the strength and in what direction it's strong.
Also look ad how to make the carbon. You can get different effects by how you lay the carbon layers on each other.
There are tricks to save on carbon and tgat is by putting an other material in the middle, but it doesn't work everywhere and it also depends on what material you use.
This way you can make parts very stiff, but weak on impact.
 
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The cool "Ground Hugger" by JQ Riley was also a DIY carbon frame, and I once considered building one.
But to this day I have yet to see any posted example at all (anywhere) of someone making one.

Brad
This guy managed it :- https://roguelsr.wordpress.com/




Not read his blog as CF does not interest me ? why when you can burn metal ......
 
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Ahh, the sweet smell of burning metal and rubber. Whoops, I should have shifted that before I started welding.

It takes much, much longer to build something that does not have a plan. Prototyping, like changing from metal to CF will be, is a three-steps-forward-and-2 steps-backward kind of thing and creeping away finish date as you tweak design changes.
 
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Switching to carbon is harder than it looks like.
But as you like a challenge, than this is it.
Still I would advice you to design the frame in a cad program first and see where the strong and weak points are.
It helps a lot.

One tip, look ad oval shapes. Round is strong but you must look ad where the force on the frame or part is coming from and in some earias, the biggest forse comes in one direction. Making it oval, makes that it's stronger in that direction and makes that you can make the carbon thinner.
 
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