zonatandem

Obviously, you don't have a c/f kickstand!!!

DannoXYZ 

Yeah, CF has a higher-to-strength ratio compared to steel, that's how they're able to build a 0.5lb CF fork. If you were able to trim down a steel fork to that weight, crashing it after a wheel falls off would've been just as catastrophic. Actually even worse as such a light steel fork would fail in normal use on rough roads.

SoreFeet

People who use carbon fiber bikes for off road shouldn't expect the frame to last as long as steel or aluminum. Any frame will damage with the right impact but riding carbon off road is asking for trouble. Lots of rocks and things can scratch the carbon up really easily. It is likely that your friend rides trails like maniac and previously damaged the frame but didn't know about it. I do think carbon is a stupid material for non professional riders but the bike stores won't tell anybody that. Most bike shops swear off steel as being primitive outdated material. I hope to see more carbon fiber riders learn to appreciate steel forks after they have a carbon blade snap. People who argue that they have broken forks of steel and ride carbon without trouble well... When a carbon fork fails there is nothing to aruge. You are either lucky or on the ground in pain. I'm using a brittle steel frame made of very thin wall tubing. I know it can get beat up pretty good. I'm affraid to ride it but it beats the potential of a carbon related failure.

hockeyteeth

Trek provides a limited lifetime warranty on their carbon fiber mountain bikes. The full suspension EX-9 is built from some heavy duty riding, so I'd imagine those frames hold up fairly well. I definitely would be cautious on a carbon frame though. Especially a mtb frame. You also couldn't pay me enough to ride a carbon fork on any of my bikes.

rivethead147

first, it's poor jusdgement from design. carbon should of not been a material to be considered for something like a mountain bike, the material has good durability from a front load pressure but not from a side load and a mountain bike considering it's use would see a lot of awkward load baring. the single reaosn that a carbon mountain bike exist is because of demand, the race community uses it, so it must be fine for other application as long as it is a 'bike'. no, not at all.

looking at the property of carbon and it's good and bad, which every material has; a good and bad, one must consider not just toughness of material but pliability as well. if it doesn't give at all, it well snap or shatter, in carbon's case it splinters when the wrong pressure is loaded in the wrong direction. think of carbon as something that likes a staright line and remain a straight line. you can wrap carbon in differant directions but when you make an object like a tube, the cross wrap only helps so much with side loading pressure.

steel, titanium, aluminum, and chrome-alloy, they all have the good and bad.the thing with a mountain bike, most engineers aren't considering various loads along with an ergonimical transfer of energy to the rear real, but the cookie cutter approach. take what has been done, it worked before, now use a differant material.

with differant material comes differant design considerations and those aren't carefully looked at in the bicycle community. the last bike that i saw that took all that into account was a cruiser designed by IDEO for shimano.

all of that said, without looking at the instance of breakage and understand the material, it is jumping the gun to say this is good or this is bad. if anything, think of ideas to re-inforce materials if the base design isn't going to change to compensate for material. for example and i don't know why i haven't seen this in the bike industry yet, mix kevlar with carbon fiber and that greatly increases what kind of side load pressure it can take, along with it using a highly elastic epoxy for the bonding helps (by elstic don't think rubber band but think plyability instead).