Why don't they make dirt bikes with carbon fibre frames?

[cheese]

I was in kiwivelo the other day and they were showing me the latest in mountain bikes. They have a $16,000 bike that had a carbon fibre frame and it was so incredibly light. So any ideas as to why they haven't used them on dirtbikes to get the extra edge that they all try so hard to get?

[honda_power]

iv seen a few pics of carbon fiber subframes being used in japan... they would cost a shitload to produce and cant be used in ama etc unless they are available to the public

[flyingcr250]

i think id rather have steel or alloy.......just for piece of mind ha ha ha

[Crisis management]

The only carbon fibre frame I know of (yes, I know I'm old and my memory is shot, but bear with me...) is the Ducati Moto GP bike and that has been fraught with difficulty, simply put, it is easier to achieve the desired flexibility (feedback) and life with an aluminium or steel frame than carbon fibre.
If light weight was the singular goal then carbon fibre may be the solution but you need to ensure the frame will last 400? hours of use in an environment where it will collide with stuff, get stuffed into other bikes and generally be beaten up. Carbon doesn't like collisions and impacts so won't last long in the crash and bash of competition (or even trail rides).

Give it 5 more years and I will be eating these words......

[hayd3n]

i was reading somewhere where they had invented a new super metal but cant remember where

[scott411]

flex is needed in a frame, even the first alloy frames were to stiff and the riders hated them, the 97 CR250 is still talked about as being the worst handling bike ever,
every brand always talk about putting more flex into alloy frames to make them feel better to the riders,

steel frames are easier to set up because of the flex that is built in it,

[peadub]

The new Husaberg 4 strokes have a plastic (cross-lined high-strength polyethylene) subframe This is probably almost as light as carbon but cheaper to produce

[george formby]

i was reading somewhere where they had invented a new super metal but cant remember where

Graphine I believe. Lighter, stronger, more expensive etc.

[avgas]

Because it shakes like a mother fucker......

Have you seen CF disintegrate - usually caused by vibration.

[Buyasta]

Graphine I believe. Lighter, stronger, more expensive etc.

Graphene isn't a metal, it's a carbon structure - much along the lines of carbon nanotubes, but created as a one atom thick flat sheet, rather than a cylindrical structure as in nanotubes.

More to the point, Graphene is probably at least 5 years from seeing any commercial application - they're finding newer and cheaper ways to manufacture it, but it's still very new, so they've brought the price just to manufacture it down from about $1,000,000,000USD/cm^2 in 2008 to about $100USD/cm^2, but that's still pretty expensive, so you can imagine what a product incorporating it would retail for.

[steve_xland]

Well if anybody has the Bucks and wants to try it , my brother is a Carbon Fibre technician

[Crasherfromwayback]

Carbon fibre frames would probably be quite deep too, making it hard to get at the engine.

[Rupe]

CR250 is still talked about as being the worst handling bike ever,

Thats what I've heard too...a lot

[B0000M]

Thats what I've heard too...a lot

lol

yet at the time i thought my 99 125 was all good...

[gwynfryn]

The reason they use carbon fibre in push bikes is that they can build it up in places that you require rigidity such as the bottom bracket, then feather it it out in other places to provide shock absorption. Generally aluminium frames have been lighter and stiffer than cf but harsh. Thats why a common solution has been a aluminium frame with a cf fork. A quality steel frame is still desirable for its ride quality albeit at a slight weight disadvantage.
I wouldn't want a cf framed mx bike!