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carbon fiber frame
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Posted by: surfercross
Has there ever been a bike that had a carbon fiber frame. It would seem that frame made from carbon fiber would be strong liteweight and have certain flex that could be beneficial. I know that the cost would be outragious but it something to think about
Posted by: spanky250
I don't think carbon fiber has very good abrassion resistance, and it is difficult to attach things to it. I'm not so sure a carbon fiber frame would be a good choice for the abuse a dirtbike sees. I would think the inherent stiffness would make for an easily broken frame, but I could be wrong. I know some race cars use it for their chassis, but they don't do tripple jumps or slam into rocks. Maybe one of these material guys here will shed some light on this?
Posted by: Patman
I have often thought the same thing (wouldn't a CF framed bike be cool?). Weeeeelll it just so happens one my cousins is on the Jag. GTP team and his job just happens to be CF lay-up (ever seen the WW of Sports crash scene with the guy sliding in the tub? That was his first job.). Anyway.... this is something that has been discussed and while it would be possible the actual weight and strength issues are pretty moot because the frame would either have large thick walled "tubes" or "solid" forms both with aluminum plates installed at key bends, joints, and wherever fasteners would be needed. The weight of the final product COULD be lighter but in reality would be equal or even slightly more than a convention frame. Also the lay-up schedule would be pretty involved because of all of the various forces involved with the suspension attachment points, etc... The abrasion concerns are pretty easily resolved with wear plates of any number of materials. Oh and the cost? Yup pretty outrageous.
Posted by: Kintan
How about duplicating a frame out of titanium.Looking at some of the mountain bike frame building companies ,I think the material would only cost 3 or 400 dollars.then all you would need is a good tig welder.any thoughts??
Posted by: OldassKDX
y'know, I'm pretty sure I saw a Carbon fiber frame for the YZ400F a few years ago in a Dirt Bike mag, dunno much more about it other than it was really expensive. Maybe Rich knows more?
Posted by: Rich Rohrich
http://www.synergymotorsports.com/
The original prototype was very pretty but seemed in my opinion to have ignored a few structural issues in favor of ease of building it. No real updates on the website so they may have decided it was too costly too produce.
15 or so years ago Armstrong built a very slick carbon road race frame that housed a 250 Rotax rotary valve twin. There are a few different Ducati carbon frames floating around in Europe as well. I'll hazzard a guess and say the loads in a 12in travel 240lb MX frame are much trickier than a road racer that keeps it's wheels on the ground all the time http://dirtrider.net/ubb2/biggrin.gif
Posted by: SpeedyManiac
They would look pretty sweet..... But I think a titanium frame would be really good.
Posted by: cujet
In the aerospace industry we use quite a bit of carbon fiber. I have a wing tip (trailing edge) section from a Gulfstream GIV in my shop that was damaged in the shop. It is very well built and cost 28,000 dollars. It is about 4x3 feet in size. It is non repairable and therefore may donate itself to a few projects I have in mind.
It is not like the carbon fiber many of you are familiar with. It uses a green epoxy and different form of fabric. It does not look really cool, however it is stronger than the standard form of carbon fiber we all know.
I think I will cut it apart and use the parts.
By the way carbon fiber tends to yield suddenly and without warning. This may be the only reason for not using it on a dirt bike. The proper form of carbon fiber will withstand the bolts and attach point stress very well.
Chris
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94 Husky 360 2 stroke, Street legal,(gotta clear my throat now)! Ported engine, FMF pipe, kehin PWK carb, full knobbies, Pro Action Showa suspension, Pro tapers. 50HP
Posted by: Norm
I've given the idea some thought because I have some composites experience and access to raw materials. But like others have posted already, the cost would be very high and there are drawbacks to using this material for a dirtbike frame.
Safety would be my major concern because CF fails catastophically, often with little warning. I've seen plenty of pix on the net of broken CF bicycle frames. A broken frame while riding a bicycle ain't cool - a broken frame while landing from a triple is downright dangerous. Repeated impact loading that dirtbikes see is probably not a smart application for a material that behaves in this manner.
Patman brought up a good point about needing to have metal inserts, which will complicate the design and possibly negate the weight savings of using CF.
Oh well, at least it's fun to dream about http://dirtrider.net/ubb2/smile.gif
Norm
[This message has been edited by Norm (edited 04-01-2001).]
Posted by: MikeT
I know they use CF on F1 cars in the frames as well as some of the suspension parts.
Posted by: surfercross
I wonder if it would be possible to make something less complicated like carbon fiber handlebars.
Posted by: Heywood
They have been selling carbon bars for mountain bikes for a while now. I am not sure why we haven't seen it tried on dirt bikes.
I think the catastrophic failure issue may have something to do with it. You would never bend bars, they would either survive or snap off. http://dirtrider.net/ubb2/rolleyes.gif
Posted by: Yamamoto
If I wipe out I would like my bars to bend rather then twisting the triple tree,ect.
If the bar did not bend on a crash I would think the impact would go to the stering stop tab,snap that off and end up allowing the bars to hit my tank.
A chain is only as strong as its weakest link.
Posted by: MikeT
I don't think I'd give Carbonsnap bars a try on my bike. That snap thing doesn't sound good.
Posted by: ButtonFly
Bimota makes (made?) a street bike with carbon fiber frame parts that bolted to other parts... SB8R... Pretty wild bike, but you pay for it too.
Posted by: Farmer John
The SB8 Bimota has the swingarm pivot portion of the frame made out of carbon fibre. http://www.bimota.it/old_site/home.htm
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<A HREF="http://www.timekeepersmc.com" TARGET=_blank>www.timekeepersmc.com
</A> 97 CR 250
I like 4 strokes...got one in my truck.
Posted by: Scrambler400
here you go...... http://mxsouth.com/c-fiber-2.jpg pretty sweet.
Posted by: kevkon
Coming from the auto racing side of the fence, I would add that carbon fiber may become more prevelant if motorcycle frames get away from the space frame type of construction and move towards an intergrated monocoque engine/frame type of construction, where a laminate material would be the way to go.
Posted by: elvismx
Another aspect of the "snap" issue is that when CF breaks, it usually ends up in jagged shards, just right for impalement. Dirt Bike did a test of a project bike (a 167-lb CR125) that used carbon bodywork (made by AirTech) throughout, and one of the fenders broke off just from the weight of mud.
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'96 CR250R, two '73 CR250M Elsinores
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