Anasazi

I am a beginner at cycling, and I ride an aluminum frame bike with carbon fiber forks both front and back.

I have a few questions. What is carbon fiber? What are the advantages to having parts of the bike made from carbon fiber?

Thanks ahead of time for your help.

Pat

I am not sure exactly what kind of carbon fiber they use in bikes, but carbon fiber is like the stuff they use in graphite fishing rods. It is merely a bundle of very thin carbon fibers. They are quite strong and light weight. They are used in forks because they tend to lick up road shock better than other materials. And they are used in many rear triangles for the same reason. The major disadvantage to carbon fiber is catastrophic failure. Metals tend to bend when hit really hard. Carbon fiber just snaps and that is not a good thing to have your bicycle do. However, the engineers have pretty much gotten around the material's defects and there are very fine bicycles made competely out of carbon fiber.

RegularGuy

Everything Pat said. Plus, carbon fiber is light and strong. It allows bicycle frames to be shaped in unusual ways. Ithink that one piece carbon frames can be especially beautiful. Carbon fiber frames can be "tuned" to specific ride characteristics: compliant in one plane, stiff in another. Some people complain that carbon feels "dead" to ride.

shinomaster

Carbon fiber is very safe for bicycle frame construction. The aluminum is more likely to fail than the carbon. In the past the joints failed because of corrosion, but this problem has been solved-so they say. Carbon fibers are woven into fabric and molded and set in a epoxy or resin to harden the fibers into a solid form.Is is very important not to over-tighten carbon components like seat posts or bars, or fork crowns as they will crack and then fail.
The real reason that carbon was first used was for making very lightweight bicycle frames. Now it is used for softening the ride of harsh riding aluminum, style, and coolness. Soon everything will be carbon.....pure joy

camshaft

Correct me if I'm wrong....
Carbon fiber takes strands of carbon, which have a very high tensile strength and then weaves them together and then cures them in epoxy. The carbon fiber weaves are by themselves not smooth. The smooth finish you feel is the smooth epoxy. If you were to break a piece of carbon fiber in half, you would be able to expose the weaves inside. There is also a similar but cheaper material called carbon fiber composite (often just called composite). In the composite, instead of weaving long strands of carbon fiber, you take very small shavings of carbon and mix them into a paste, and the pour the paste into a mold. The final result looks somewhat like a coarse plastic, but is stronger. The composite can therefore be molded into various shapes more easily than true carbon fiber, but it isn't as strong as the woven carbon fiber and is consequently cheaper.
Carbon fiber has some great properties. It's strength to weight ratio is better than most common metals, which is why you also see it being used more and more on the bodies of high end sports cars and race cars. Aside from its light weight, it's fairly good at dampening vibrations, which is why in cycling they'll put carbon fiber in select places to dampen the road vibrations, such as in the front and rear forks and the seat post.

Austin

ImprezaDrvr

Aluminum is a brittle metal and will often snap under a great enough load. With bicycle frames, it's rare for a bike to just break under its rider anymore. Early carbon bikes, as well as earlier lightweight aluminum bikes, had their problems, but you don't hear of spontaneous catastrophic failure all that often these days.

FLY02

Carbon Fiber is a interlayering of actual carbon fibers and fiberglass. They are coated with resin to give them that shine and protectant. CF is stronger than steel when used in some applications but is extremely brittle when pushed the wrong way.


Here is some carbon fiber that i own....heeheh....it's my car. Fiber Images is making me a carbon fiber trunk right now. I really want a CF road bike to match my car.

camshaft

[QUOTE=FLY02]Carbon Fiber is a interlayering of actual carbon fibers and fiberglass. They are coated with resin to give them that shine and protectant. CF is stronger than steel when used in some applications but is extremely brittle when pushed the wrong way.

As far as I know, carbon fiber doesn't necessarily have to have fiber glass in it. I believe it can be, and often is, all carbon fiber, at least in the more expensive applications.

Austin

Anasazi

Thanks for answering guys, now I know more about carbon fiber. And what a cool car Fly02.

ImprezaDrvr

fly, what kind of car is that hood on?

roadwarrior

One of the advantages of carbon is that is does not develop a "memory"...think of a paperclip...if you bend it back an forth enough, it will break. Carbon will not do that.
The opposite of this is that you can't "lean" the bike.. a carbon bike will ride a lot differently, especially in the turns.
Not all carbon is the same..for example, Look makes a couple of carbon frames, the 361 and the 381I (the team bike). There's about a thousand (if my memory is decent) dollars difference in the frame cost.
The TCR Elite, Giant's bike is a carbon composite...not a full carbon bike.

Do your research and ride both types, aluminum and carbon, and the one that feels the best is the one to get.

I sell both and typically the customer is coming in to buy a new bike and has an old (like pre-1995 or older) aluminum bike and then they get on the new stuff and cannot believe the feel. Both are good, it's just a feel issue when you can pick either.

Carbon is very strong....Indy car drivers trust their lives to carbon fiber. That's how strong it is....but how it translates to the comfort your rear end will feel riding a bike is up to you.

FLY02

It's a 2002 Honda Civic EX. I don't have any updated pics. The most recent ones are of it at NOPI Nationals car competition.......

It was a show car but now I've stripped the car mostly and run it at the track. I have Stafford Fabrications in cali building me a turbo system for it.

Anasazi

Roadwarrior,

I'm new at cycling, so what do you mean by you "can't lean the bike" ?

Thanks.

roadwarrior

Bike's got a bit of "give" you can feel it go through a turn...in crit racing, going through a corner at 25+MPH, it's important..that's why I alluded to the feel of the bike. There's not a ton of flex in carbon..it is stiff.
Most carbon frames are really designed to be racing frames. Aluminum is all over the place from hybrids to mountain bikes to touring and heavier duty riding frames...they are a bit heavier, but are more durable and comfortable.
Think of it this way...carbon is like a sport suspension in a car...stiff but very responsive. But not real cushy. So it depends on what you are after. Responsiveness like a racer, or a softer ride for fun cycling.

ShinyBaldy

The TCR Elite isn't actually Giant's primary racing frame - it is a more of a comfort highperformance hybird...

The TCR Composite is full carbon...

all carbon frames are composites - epoxy + carbon fibre = composite.

MichaelW

Some Carbon frames do use glass fibre as an interface to separate metal inserts from carbon. This avoids electrolytic/galvanic corrosion. No frames use glass fibre in the weave. Glass is heavier, weaker and the cost of a frame is in its layup, build, and the mould. materials make little difference.
Some forks use a layer of kevlar which is weaker, but does not snap.
The big advantage of C over Al is not weight, it is in aerodynamics. You can fabricate far more slippery shapes from C, and for racers, this makes a bigger difference than a couple of gramms in weight.
The big dissadvantage of C is that it is quite soft and vulnerable to surface damage.

ShinyBaldy

I believe you are incorrect in your reasoning and understanding - alum as a structure is no more durable than a carbonfibre epoxy frame. Esp when lightweight is wanted - alum tubing becomes extremely thin.

Cannondale's CAAD7 is a good example - it is an ultra light frameset made completely of alum, to sacrifice for the light weight - the warrenty is only at 2 years with aggressive riding (whereas Cannondale usually gives a lifetime warrenty).

Carbon frames are no less cushy than alum in general - alum utilizes oversized tubing - which usually results in frames that are plenty stiff, if you want comfort, go for steel.

But the comparison between alum and carbon is false - the reason why carbon isn't used more often in general applications is because it costs more to develop and research - alum is just more cost-worthy as a beater bike because it is so darn cheap to use.

dexmax

Agreed.

(Steel is real!!!!! Go steel..)

anyway, stiffness is not directly material related. Several factors kick in, such as tube design/specs, frame geometry, etc.

Carbon fiber is hard, true. But it will flex to some amount, safely. That is why Bikes with carbon forks and stays will ride more comfortably than aluminum forks. But this may not always be the case, but usually true.

ShinyBaldy

I think one thing that isn't mentioned much is - steel is actually stiffer than alum if the same dimensions were used in tubing (oversized) - but that'll mean a unecessarily stiff and heavy frame.

The beauty of carbonfibre is - if done right - the composite's designerability allows you to manuiplate the material properties much more than some other materials.

Instead of being only to change thickness, shape of it - you can decide on how the fibres interact and where it is located... which I guess in theory is something you can do in metals, but who'll make tubing like that?