# Carbon Mountain Bikes



## Peter10 (25 Oct 2010)

Hello all,


I have ridden mountain bikes most of my life before converting over to road bikes earlier this year as I hardly (if ever) did any actual of road riding. I want to get back into it and have been doing a little bit of research into a new bike. I keep seeing people saying carbon mountain bikes are a big no-no and should be avoided. Is there any reason for this or is it preference? I know someone with a carbon MTB (Bianchi Pulse) and he loves it, but the guy in my LBS said they should be avoided.

I probably can't afford a carbon MTB anyway, but wanted to ask what is the issue with them?

Pet.

On a side note, rather than starting a new thread, who are the main players in MTB's (as in do a good range of entry to top end bikes?). Seems every man and his dog sells a MTB these days.


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## Globalti (26 Oct 2010)

I'm in the same position as you; I rode MTBs for 22 years but went over to road riding 18 months ago and haven't done more than two MTB rides since. Recently though, I tried somebody's Specialized carbon MTB around a car park and it felt absolutely sublime to ride.

The reason why carbon is mistrusted for MTBing is that it is extremely strong and light as a structural material but has very poor resistance to knocks, so if you fell off your carbon MTB (which you inevitably will) and clouted a tube on a rock it could break the resin that bonds the carbon weave, in which case it becomes something like wet cardboard, probably still very strong but a bit floppy.


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## lukesdad (26 Oct 2010)

Had my scott endorphin 10 years still going strong.


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## Kestevan (26 Oct 2010)

Some people have an inate distrust of carbon fibre. 

They believe that one night they will come home and find that the carbon fibre has turned to cheese and their bike has melted.


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## Tim Bennet. (26 Oct 2010)

> but has very poor resistance to knocks


Is that why they use it for the safety cell in racing cars and boats? Do the drivers walk out unscathed because the resin that holds the weave has broken away? What a load of cobblers! 

A carbon fibre structure can be as strong as you like. If it *weighs the same as aluminium or titanium* then it will be many times stronger and stiffer. Any blow strong enough to break a carbon tube will be enough to totally bend or snap a tube in other materials.

However because carbon is so strong and stiff it allows designers to reduce (if they choose!) the wall thickness and make it as light as possible. A similar weight would be impossible with metal tubes as the wall thickness would be so thin it would fail strapping it to the bike rack on the way to a ride.

And don't get hung up on its mode of failure either. If you have two tubes *of the same weight*, the forces that will buckled and catastrophically destroy a steel tube will be shrugged off by a carbon tube because it will be massively over strength. If you make a steel tube the same weight as an adequately strong carbon tube, the steel tube will be so thin you could crush it in your hand. Lightweight carbon parts fail because they have been engineered to pander to weight weenies, but they're still way stronger than any other material of the same weight.

Carbon can deliver massive strength at reasonable weight (Car safety cells) and adequate strength at very light weight. By wisely to get what suits your needs and you'll be happy.


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## Rammylad (26 Oct 2010)

Don't know much about the science but love my Scott Scale which i use for events as its so much lighter and responsive than my full sus Trek.


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## ColinJ (26 Oct 2010)

I always felt a bit worried about CF mountain bikes. That's probably a bit illogical,given that I have been perfectly happy riding my Cannondale road bike which has CF forks. Having said that, I received a message on Thursday from someone who got pretty badly hurt recently when the front of his CF mountain bike suddenly snapped clean off - there's that catastrophic failure mode in operation!


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## 02GF74 (27 Oct 2010)

ColinJ said:


> s. Having said that, I received a message on Thursday from someone who got pretty badly hurt recently when the front of his CF mountain bike suddenly snapped clean off - there's that catastrophic failure mode in operation!




isn't there a post on here, some forest trip - Dalby? where a steel frame bike snapped in two?

this catastrophic failure mode is not limited to just carbon fibre.

there is always restistance to change; back in the day when aluminium alloy frames first came out, everybody was up in arms much in the same way yet you'd be very hard pressed to buy a top end road or mountain bike made from steel.

(I am biased ofcourse having recently bought a CF mtb but have been riding on CF posts and forks for some time)


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## 02GF74 (27 Oct 2010)

here is the post I referred to;
https://www.cyclechat.net/


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## addictfreak (27 Oct 2010)

Rammylad said:


> Don't know much about the science but love my Scott Scale which i use for events as its so much lighter and responsive than my full sus Trek.



Isnt the Scott Scale fanastic!

I have one, probably the best MTB i have ever owned. Its mega fast even with my fat ass on it.


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## Cubist (27 Oct 2010)

OP, you ask about main players in MTBs. You need to define your needs. If you're talking about CF I assume that you are into XC rather than freeride!

Having said that teh following mainstream makes cater for all disciplines: Cube, Specialized, Giant, Trek, Genesis,. Halfords' Boardman and Carrera MTBs are excellent spec. Pinnacle at Evans, Decathlon at Decathlon, Focus at Wiggle, some good 'uns to chose from. Many many more, but a lot of same old same old among the exotica.

Get a copy of What Mountainbike, as they do a guide to what sort of bike you want for what sort of riding, and then a guide to what's good and what isn't so good. 

Think of a budget and then add half again. Not for extras, but because whatever you think you want, then the next price point will be better......

Be hnest with yourself. If you want to ride on towpaths, you don't need a 800 quid bike. If you want to ride trails you won't get away with a 300 entry level bike with c rap forks.


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## Banjo (27 Oct 2010)

Have a look at this video of a guy doing stunts on a carbon fiber road bike. 
View: http://www.youtube.com/watch?v=5z1fSpZNXhU


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## BigmechUK (27 Oct 2010)

Carbon cannondales are amazing! Super light and yet super strong! Bit expensive but worth the money.


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## jonny jeez (29 Oct 2010)

Peter10 said:


> Hello all,
> 
> 
> I have ridden mountain bikes most of my life before converting over to road bikes earlier this year as I hardly (if ever) did any actual of road riding. I want to get back into it and have been doing a little bit of research into a new bike. I keep seeing people saying carbon mountain bikes are a big no-no and should be avoided. Is there any reason for this or is it preference? I know someone with a carbon MTB (Bianchi Pulse) and he loves it, but the guy in my LBS said they should be avoided.
> ...



Peter, I think you and I may have been separated at birth!

I am in almost the exact same position. I ride frequently on the road and do want a good ali frame road bike (as mine is sadly showing signs of age now) but having recently re-found my love of off roading so also want a new cross country bike. (santa's going to be busy this year I think)

I am "attracted" to CF just because it smells like quality but I am also resistant as at the end of the day, I am not a serious off road rider (I'm not out every weekend plodding out mile after mile) and am not the smallest chap in the world so the weight gain would be less beneficial to me.

Tim, I'm interested in your reply as it makes perfect sense...but what is the conclusion...is carbon "worth" the extra cash or is it just a gimmick to someone like me who rides off road around once a month.

Sorry to hijack your thread Peter


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## jonny jeez (29 Oct 2010)

Cubist said:


> Having said that teh following mainstream makes cater for all disciplines: Cube,



no surprise to see them top of your list Cubist ...I have to say, they are very pretty bikes and weren't a manufacturer that I had heard of until recently.


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## Peter10 (29 Oct 2010)

Banjo said:


> Have a look at this video of a guy doing stunts on a carbon fibre road bike. http://www.youtube.c...h?v=5z1fSpZNXhU



I love that video saw it a while back, very cleaver I think also.

I have had a look at a few bikes, still unsure of what I want though. I had great fun today at night cycling through a trail on a borrowed Specialised hard tail bike (not sure of the model). Starting to make really go and buy one now.


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## Cubist (30 Oct 2010)

jonny jeez said:


> no surprise to see them top of your list Cubist ...I have to say, they are very pretty bikes and weren't a manufacturer that I had heard of until recently.


Nor me until I went into the LBS to buy half a dozen Meridas for work, saw the Cubes and they sold themselves. Then young Cubester saw the attention and fell in love with it, and of course I had to get a Ltd for XC riding. Can't fault them, and they are incredible value for money now, with 2011 bikes getting better spec components pound for pound than a lot of the competition. They don't seem to cater for hardcore trail riding yet, but I would recommend them any day for trekking and XC/racing stuff. 

By they way OP, I think for racing and XC stuff, even some moderate trail riding, carbon will be plenty strong enough.

Just to throw a bit of extra thinking at you, have you thought about Titanium? If you are into XC or trail and can afford to be thinking about carbon bikes, then Ragley, On-One and various others do some very good Ti frames, which I would choose over carbon. I saw a Ti frame for £700 in a mag the other day, which is extraordinarily cheap. Budget another 1200 for components and you can build your own!


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## KEEF (30 Oct 2010)

Kestevan said:


> Some people have an inate distrust of carbon fibre.
> 
> They believe that one night they will come home and find that the carbon fibre has turned to cheese and their bike has melted.
> 
> ...


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## Tynan (30 Oct 2010)

that driver cell example is nonsense, if you're happy to discard your carbon frame after a knock then great, you're not going to drive the car agai after having to call upon the carbon fibre crash cell are you

that vid is very impressive but the frame doesn't take an impact does it, that rider is very smooth, no-one is disputing that carbon fibre frames are strong


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## DrSquirrel (1 Nov 2010)

Tim Bennet. said:


> Is that why they use it for the safety cell in racing cars and boats? Do the drivers walk out unscathed because the resin that holds the weave has broken away? What a load of cobblers!



If they have a crash, do they use it again?

CF once cracked - in short - can't be repaired (in long, maybe).


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## jethro10 (1 Nov 2010)

Tim Bennet. said:


> Is that why they use it for the safety cell in racing cars and boats? Do the drivers walk out unscathed because the resin that holds the weave has broken away? What a load of cobblers!



In racing cars they are designed to be thrown away after a big accident as they can afford new ones. Folk don't want to do that with a bike
Your not comparing apples with apples here I'm afraid.
Yes carbon fibre is very strong but it does have poor impact performance.
Oh, and by the way, it's usually Kevlar fibre in racing car stress points and cells nowerdays, or at least has quantities of kevlar in there.

Jef


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## Tim Bennet. (1 Nov 2010)

No the carbon safety cells are NOT designed to break. Nor do they.

All the other components of the car are designed to be ripped of to both absorb the crash energy and reduce the total mass involved in the final impact. But the safety cell remains intact.

No amount of fairy stories and half understood science is going to change the fact that carbon fibre is weight for weight far stronger than any other bike material.





> CF once cracked - in short - can't be repaired


Of course it can. It's skilled work but not not hard.


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## Howard (1 Nov 2010)

I was under the impression that the problem with carbon bicycle components is a troubling combination of a catastrophic failure mode combined with an ability to disguise structural damage that would be immediately obvious if the component was made of metal. 

So just like Alu, then, except that the wallop the bike received last time you where downhilling may - or may not - result in the untimely collapse of your seat tube, and nobody short of round trip back the manufacturer will be able to tell for sure, and even then I've heard they'll struggle.

That's not to say I wouldn't buy one - I'd just think very hard about it.


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## DrSquirrel (1 Nov 2010)

Tim Bennet. said:


> Of course it can. It's skilled work but not not hard.



Skilled work? but not hard?

I did put "in short" for a reason.


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## fido (2 Nov 2010)

I've had a number of CF MTBs over the years and thought they were also great (the reason I've had a number is because the bloody things keep getting pinched).

The only failure I ever had was on a secondhand giant CFM frame I bought but even that went for 5 years for the original owner and a further 5 for me. I then had a proper ding with a car that kind of put a splintered hole in a chainstay (it was actually still useable with no discernable increased flex) so It was hardly down to any inherent weakness of the material.

In order to get the frame in the bin I had to cut in in half so I thought it would be fun to achieve this by throwing a concrete block at it - which I had to do again and again and again....etc. before in finally broke in any catastrophic sense.


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## BigmechUK (2 Nov 2010)

CF bikes really are solid and light weight. worth the money totally! i have had 3 cf bikes over the years and they are solid


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