Corbon fibre of high quality Alu for a high end XC / trial bike?

Question

There are quite a few high end XC trail bikes coming out with carbon fibre frames, like the IBIS Mojo or top end Stumpies. Is this the new thing? They are light (at least a pound lighter), but what are the drawbacks? If you were spending a lot on this sort of bike now, world you go carbon, or get a similar priced Alu frame bike?

Answer 1

come on hnab -- carbon fiber is much stronger than aluminum or even steel of the same size. if you saw carbon messed up it was more cosmetic than aluminum. there has to be a reason why racing vehicles are carbon fiber (strength V weight) and why aircraft are going carbon fiber (strength V weight). must be a good reason for bikes to go carbon too (strength V weight).


EDIT: 2 more cents on composite. It is more fracture resistant than steel, it is stronger. Undeniable facts. What is happening when you see broken frames in MTB is frames that were poorly engineered with minimal wall thickness. It's not the carbon, it's being light as possible and cheap as possible. Carbon frames will improve.

Answer 2

There is a slight advantage weight wise. Carbon frames have been around XC a long time. While I think all materials can make great frames I wouldn't buy a carbon XC bike. The reason being that I'd have to pay for it and it would have to last a long time. I've said this before: xc riding I've seen 3 frames messed up, all were carbon. Carbon is very strong but in crashes it can be damaged quite easily. If I were sponsored and my bike given to me I'd ride a carbon frame - no problem.

Answer 3

Carbon is much more expensive than Al. However, it is quite a bit lighter. As for durability, you can get into a pretty heated debate about that, but unless you get into a major crash, it should hold up just as well as Al if not better. Some carbon bikes and parts do have "unofficial" weight limits. As a 220 lbs rider, I don't think you will ever see me on a carbon fiber bike even if I could afford it. If I was 150, you bet.

Most people also talk about the strength of carbon fiber bikes. The bike is very stiff and you don't lose power because the frame does not flex.

Answer 4

McG, your enthusiasm for carbon is charming. Carbon fiber has many wonderful qualities, however, impact resistance is not one of them. Carbon fiber fractures on impact and ufortunately, if it doesn't crack immediately, it will fail later. So, while it is lighter and stronger than steel or aluminum, I think it is a very suspect material for a mountain bike - that is unless you never crash.

Yes, race cars and airplanes are made of carbon fiber. Yes, carbon fiber is strong and makes a wonderful material for race cars and airplanes. The difference is most of us want to be able to use our mountain bike after a wreck while few race car teams or airlines have any expectation of using their machines after a wreck.

I wouldn't have any problem with a carbon fiber road bike, but you still must be careful with one. In fact, a rookie mechanic at my local bike shop clamped a carbon fiber bike into his work stand. The torque placed on the frame from tightening a bolt cracked the frame. Oops...

So, would I love to have a carbon fiber mountain bike? Absolutely, especially if I was sponsored by a carbon frame maker! Do I intend to go buy one to save a small amount of weight for XC racing? Not on my nickel!

Just my $.02. Hope it helps you out.

Answer 5

Carbon will make the bike about 3 pounds ligher, but IMO it's not worth it. Weight gives you more stability when going downhill.

While aluminum might tend to scrape or bend on a nasty fall, carbon fiber is most likely to break. And also, carbon fiber is more expensive. You're better off buying an aluminum frame and equipping it with high-end components.

Carbon fiber also reduces vibrations from the ground, but i don't think it's much different from normal bikes.

IMHO, carbon fiber is for weight weenies and for people who take bike racing seriously.

I was thinking of buying a Rocky Mountain XC bike, but i am

Answer 6

CF is very though and light, and can resist a lot. But, if you get a ding.. bye bye frame. If it hits a rock on a fall on a wrong way, probably bye bye frame. When installing stuff on it (like a front deraileur) you have to make sure it's not overtightened, which again, can be a bye bye stuff.