Carbon fiber is actually a really cool material because the it gets its strength from the way the fibers are oriented. If you have a block with all the fibers in one direction and put tensile stress (pull it) on the direction of those fibers it will be extremely strong in light, but go against the grain and it will just pull apart very easily. By layering the fibers you can actually control the strength in different directions and design the frame for the actual stresses it will be under, instead of having relatively equal strength in every direction which is only really controlled by the thickness of the material.

Unlike carbon fiber there is not as much variance in the thickness and shape of the tubes with steel, Ti or Al, mainly because the frames are based around drawn or welded tubes and you can only vary them so much (double and triple butting and aero profiles ect.). So with carbon fiber you can control the strength of the material in different stresses and have a huge control over the tube shape and thickness through layering the fibers. Because of that you can make an extremely stiff frame with much less weight than the other materials and with much less hassle.

Also, comparing Steel and Ti and Al, the young's elastic modulus (E) has the most influence over their properties. The elastic modulus is a simplified relationship between the amount of stress (tension or compression) the material goes under and the amount of strain (% lengthening or shortening). The higher the E the less deformation or flex you get for that amount of stress. Modern steels have the highest (~195 GPa)then titanium (116 GPa) then waaaaaay at the bottom 6061 with 70 GPa. That tends to be the reason why Al frames have super big tubes (cannondale hoooo), they need a higher second moment of inertia to resist bending (takes too long to get into).

Also, ***I think*** and DW can probably either prove me wrong or back me up here, but Ti tubes don't use the large diameters that aluminum does and vary wall thickness instead, which is why they tend to be more flexy and not super stiff like Al (tube diameter plays a big part in stiffness). Not only that but Aluminums E is so low, they need to make the tubes extra stiff to prevent non-eleastic deformation.
****I think****

I am not a frame builder so I'm not 100% sure about that last paragraph, maybe someone else can give some input.

If it matches your shoes, it must be TRACK!

Don - that sounds like a bunch of Detroit claptrap regarding the magical carburetor NOT existing. What are you hiding from us? That the next wave of frame technology will incorporate the fourth element, Plasma?

Stop with the cryptic BS and get to the point, man! Or should we all just come to NAHBS?

Obviously you are right. That's why the pro tour rides steel!

Duret, the least you could have done is post pics of bike that were NOT the earliest generations of said materials. Come on, the Vitus and the Giant with lugged alu/carbon? This is not the early 90's.

Both materials now enjoy being built into some of the stiffest frames you will find. Stiffer than steel? Usually.

reference to gitzo's basalt tripods? or did i miss the joke?

fsnl
sparky

yeah that was kind of my point.


EDIT: and just to be even more clear by "kind of" I mean exactly.

I chose two outdated flexy examples of cf and Al to point out the the flaws of Judas' absurd statement that ti makes noodles. Yes a lot of early ti bikes(and some current touring ones) aren't the stiffest out there but the same could be said of early Al or CF. Ti, Al and CF are all made into incredibly stiff frames now and just because you can find a noodle made out of ti does not mean that ti frames are doomed to being flexy any more than with CF or Al.

EVEN MORE EDIT: apparently I was still not clear enough. the words above those pictures were purely sarcastic. I do not think that steel is the only material that can make stiff bikes. In fact I think ti, al, and cf all make better light stiff frames then steel does. I enjoy riding bikes made out of all these materials(and just wish I had more oportunities to ride ti ones.)

close enough to a possible truth though:

http://www.gitzo.com/Jahia/site/gitzo/pid/4696?rId=2

fsnl
sparky

dutret - i thought you rode an aluminum frame... the fuji track pro?

Nope. I will be riding that giant next week though and hopefully this once or twice.
http://images.competitivecyclist.com.../e1_zoom_1.jpg
(note this bike is anything but a noodle.)

Ah I haven't seen many Ti bikes, didn't know they were doing the oversized tube thing too. Seems like the thinner walls idea is asking for dents to me, and aluminums crumple tendancy keeps me riding steel.

That is until I finally break the TdF scene and have a need for carbon fiber.

ultra-stiff lightweight steel is just as bad as Al if not worse. OS Ti at least seems substantially more durable but I have never owned one.

Makes sense, can you still change the dropout spacing as easily on the new steels as you can on older ones? And can you do that on Ti bikes too? I'm pretty sure it isn't recommended with Al but am a little clueless on the new stuff.

I like my thick downtube. It's really stiff.

I call mine a "downtube" too. Heh.

This is getting really hawt...

I always thought head tube was more appropriate... I'm a tall guy so all my bikes have really long head tubes. Probably longer than yours.

Size doesn't matter...








































Unless it is aluminum ;)

If nothing else hate on the fibers make for some good threads. Ha!

Yeah but my ball bearings are totally smoother.

Thats because you have loose balls though.

I try to avoid the habit of repacking my bottom bracket every night. Its messy and not designed to be used that way.

Blah blah grease in my seat tube.

But it feels so good! And it's so cool when all the grease oozes out.

I can fit like two feet of post in my seat tube...