With every manufacturer now producing carbon fibre bikes how are they really working out for those of you that have shelled out their hard earned on a Cannondale, Giant, Ibis etc. I keep looking at the hype and the sniffy comments about competitors manufactuing techniques of folding weave but are they as light as aluminium? Do they last as long as titanium. Are they as springy as steel?

Mostly do they last longer than 2 years? Or is the old maxim of 2 years carbon fibre, 4 years aluminium, 10 years steel and a life time titanium still hold true.

I raced on a 14-year-old carbon frame yesterday, nuff said. Carbon is like any other material in that if you use enough of it you it will be stiff and reliable and if you don't it will break.

My Giant XTC Composite frame is amazing, i got it maybe a week and a bit ago - super stiff where it needs to be, absorbs the buzz from the trail and is lighter than aluminium by a good old way. It is a very very fast bike.

In terms of longevity, i'll let you know. So far it seems very robust, i have scuffed the paint off here and there in places already, revealing the top layer of carbon, but that doesnt seem to of affected anything.

I would definitely recommend one!

Interesting response all positive so far. A mate has a Whyte whose swing arm came apart but it didn't look like a CF problem. I've used Easton CF bars for years without a problem. Having pulped several ally frame in my time I'm cautious about going to a less tested material. The glut of biks this year from most manufacturers in CF has got me interested. I'm just surprised that if the material is that much stronger than ally that they don't weigh significantly less. Many manufacturers (Scott and Giant I thought - Smidge you may want to correct me) seem to have bulked up the joins to make them stronger but if its stronger in the first place is that because it doesn't bond that well? In which case I don't want to go near it, or is it that they are still learning about the material in which case I'm interested but next year.

I think the extra mass of carbon comes from improving impact resistance in exposed areas. Eg. if you smack an aluminium ransom downtube against a CF one, the ali one will die first.

So its stronger and they use more than they need. Why?

Some manufacturers don't use more than they need. Scott for example produce a 1kg carbon frame which is as stiff as you'll ever need. A Scandium frame in the same size will be 1.2kg and I'd put money on the Scott lasting longer than the Scandium.

What puts me off carbon frames is that I ride down quite a few fast stoney descents and can hear the stones being flicked up by the front wheel and bouncing off the downtube . I may be wrong but I trust steel or alluminium more than cerbon fibre to survive this kind of treatment.

Just buy one with a lifetime warranty, no worries.

Neil has a good point. I have dinged my ally frame in the past with a few substantial rocks - is the suggestion here that carbon fibre doesn't ding just shatters? That would be kinda worrying despite a lifetime guarantee. Having been taken off a mountain once by a paramedic team because of a bike failing under me at speed I don't fancy it twice. The bike had a lifetime guarantee but I learned I didn't. So any full on free ride/down hill rigs in carbon fibre yet?

I shattered a pair of carbon ski sticks last week but aluminium ones would have folded in the same crash.

Unfortunately "Lifetime" in warranty terms may only mean a few years in reality! It depends on the purpose/ use! That said some of the bike companies are very good with their cover eg Specialized and Marin.

I worry about high pressure impact damage from flint etc.
T

Have a look at something like the titus racer-x carbon, that comes with a replaceable plate on the downtube to prevent rock damage

Got two massive chips (chunks?) out of my carbon Stumpy downtube. The granite rocks were roughly the size of my foot and would have damaged any frame. Still going strong and seemed to be built to cope with it.

I didn't buy it because of strength, lightness or rigidity. I bought it because it looked pretty. Really I did. :)

Queeg thanks now thats what I wanted to hear about real war stories and damage taken. Whilst most of my riding is X country I like using one bike for everything and I've never been able to jump from bike to bike and feel confident. On paper carbon fibre should be the best but I can't understand why the frames are so heavy when the material is 50% lighter than ally for equivalent strength to weight and in practice its at best only 20% lighter. So why are the bike companies over engineering it so much?

To build in that margin for error. Stiffness is a huge factor in the bike industry too, that's where carbon frames tend to excel over their alu counterparts, they're lighter whilst being massively stiff in comparison.

Incidentally I've been riding carbon MTBs on and off for 5 years, never had any major problems, despite various crashes and knocks.

Like i say i have the 2007 Giant XTC Composite, the joints are a bit bigger than on last years XTC, but this is to give it better impact resistance to rocks etc.

My bike ride the t'other day involved massive amounts of clay then about 2 miles on loose gravel, the cumulative effect was stones being smashed at high speed from the sticky mud laden tyres onto my down tube. All i got was a very slight scratch to the paint (imagine a minor scratch on your mobile phone screen).

I thought exactly the same: one rock hitting it and boom - big accident due to broken carbon. The truth is, that's simply not the case, my last aluminium frame would of been dented by the pebble dashing, my carbon frame, as i say, was untouched - i was surprised.

Weight wise, my Carbon XTC frame weighed in at 1023g - an aluminium XTC would be a good bit heavier, so the benefits of carbon mean it can be much stronger with beefier joints whilst remaining lighter. So far i have been amazed at the strength to weight of this stuff, it really seems like a miracle material.

Also as Nick suggests, it's not all about weight either, carbon can be manufactured to be stiff where it needs to be, whilst allowing flex in other areas/directions to absorb shocks etc. Great stuff - i would seriously recommend.