The carbon debate

teabag73

Hi all - new boy here so please be kind. Been looking to buy new mtb for some winter training (from a road/triathlon background) and was wondering what the thoughts are on carbon mtb frames? there seems to be a mixed opinion - some peeps saying steer clear at all costs!! Anyway I came across the following and was looking for some advice - is it a good buy or not?? will the carbon disintegrate if I drop it??

http://www.jejamescycles.co.uk/id30438.html

any advice very much appreciated.

milkywhite

Good race/XC bike. At least one person on here I know of that's got one, and they love it.

Might need a couple of upgrades to make the most of the frame, but that's at your discretion, and probably only when things break/wear out.

Obviously, it's only a good buy if it fits. They only have 15" in stock there.

In general carbon is great. Until it gets damaged that is. It won't just disintegrate like some people seem to be suggesting. Look after it and it will stand up to general use and the odd bit of abuse.

teabag73

cheers milky, I'm 5'5" so i reckon 15" will be about right. I tried a 15" specialized and that seemed to be right size.

Thanks for the reply.

D

milkywhite

Means nowt. Different makes have entirely different geometry. Chances are it might fit, but you'll never know unless you ride it first.

I think XTCs have long top tubes.

BlackSpur

teabag73 wrote:

will the carbon disintegrate if I drop it??
.

No. When used correctly, carbon is just as strong as aluminium. Unlike metals it does have a tendancy to snap, instead of bend, but if you use it for it's purpose this will not be a problem.

teabag73

Thanks for the tip, I wondered if the carbon would delaminate if "knocked" on a sharp edge, rock etc?

I only intend to do trail type riding, maybe some singletrack - can't see me doing technical stuff, huge drop offs etc. My feeling is that the Giant XTC composite will be fine for my needs - providing it fits me comfortably and at over half the original price - maybe I should stop messing and buy it!!!

A friend recommended buying a 600 quid ali bike instead - something like a specialized rockhopper, commencal combi disc, kona etc - but I think this is more bike for the money!

Northwind

With a well made frame, the impact needed to snap a carbon frame will almost always bend or break an aluminium one anyway. Carbon will probably look a bit more dramatic if you do manage to break it but aluminium would be just as knackered.

In general metal fails soft while carbon fails hard (ie, metal bends, carbon snaps) but offsetting that is that it's very, very hard to break good quality carbon fibre. Unfortunately there is, has been and will be a fair amount of carbon fibre rubbish out there which I think helps to prejudice people against it- lots of people have had bad experiences with bad carbon, and so just think "carbon's rubbish". But if you bought a steel-framed Apollo and it was rubbish, would you say all steel frames are rubbish? Also, a lot of carbon parts are built light, or are just reproducing their metal forebears in composite rather than actually being designed around the new material, which obviously in both cases makes for a weak part.

carbon does have one other downside, which is that people expect it to be pretty. I have a few works-spec motorbike carbon parts, and they look like c**p compared to consumer-level parts, because they put a lot of effort into getting a nice uniform cosmetic finish on those. The works parts are made for strength, and they couldn't care less what they look like. It's kind of a truism in motorbikes that painted carbon fibre is stronger than naked carbon fibre, because the topmost cloth of the naked carbon was laid up purely for looks, while the painted carbon fibre can be built 100% for function.

ratty2k

Hmm, had a demonstration by the guy at the LBS (ex Scott dealer) He had a sawn off piece of top tube from the carbon MC20... Which he whacked onto the edge of his workbench with a lot of force.... followed by repeatedly smacking it with a hammer. Net result? Chipped lacquer.
The top bit you see with most carbon frames is a "pretty" one, and has almost no strength in it, but it will protect the underlying strong weave from minor knocks. Also, have a look at Helicopter tape as an extra barrier.

.blitz

teabag73 wrote:

any advice very much appreciated.

FWIW I have a CF road bike that's been down the road several times and as much CF as I can fit on my MTBs.

I don't know why CF has this 'fragile' image - some people can break a a wheelbarrow but it's not like any bike manufacturer is going to make a CF frame just because it looks good. Fit and forget IME.

Kiwi Kranker

Well I have what was considered to be a folly a few years ago, a Carbon all mountain freeride bike. I am a rubbish rider so it tends to get thrown away from me when I mess things up and or just generally screw something up.

I am light at 76kg but the result from my crashes and bails is nada. A few scratches here and there but thats it. As long as you use it for what it is meant for it will be fine ie no proper downhilling on a 1kg xc frame!!

I have owned a spesh S works carbon HT in the past, i was just as rubbish on that and it survived well too.

Good luck!

teabag73

Cheers everyone - thats helped me loads. Think I'll be purchasing said wee beasty and we'll see what happens!

cjw

Northwind wrote:

carbon does have one other downside, which is that people expect it to be pretty. I have a few works-spec motorbike carbon parts, and they look like c**p compared to consumer-level parts, because they put a lot of effort into getting a nice uniform cosmetic finish on those. The works parts are made for strength, and they couldn't care less what they look like..... laid up purely for looks, while the painted carbon fibre can be built 100% for function.

Exactly right. The newest Scott carbon bikes have abondoned the pretty carbon weave effect for plain black. saves about 100g apparently..... I don't like them

paulio40

cjw i have a scott strike with the pretty carbon weave (4 years old now and still looks awsome).To the author of this post i was a bit worried before buying my scott strike.Over the last 2 years i have upgraded it to xtr groupset,chris king hubs on hand built wheels,thompson seatpost and stem ect.In answer to your question i every faith in carbon and would definatly purchase one in the future.One final note,on speaking to the guy @ scott uk i asked him what the lifetime of a carbon frame is,his reply was lifetime unless it gets damaged from bad knocks ect because it does not fatigue like metal

cougie

Thats a hell of a saving on the Evans bike isnt it ?

lovewales

I have that exact bike bought last year from James' . I only went in for a set of pedal, they turned out slightly expensive :shock: but I fell in love with it. As someone says they have a long tube tube which I like and at 5'7" I bought the 17" frame but then they also offended me by telling me I didn't have a usual female body shape because I have short legs and long body :?

I had a fairly spectacular crash on mine at the start of summer where I miss judged a jump and landed with the front wheel solidly wedged in a gulley and me over the bars, the frame was OK but a new front wheel was needed as well as a lot of TLC for me!

I was going to change the forks for the rock shocks off my old bike but decided against it, as I was quite surprised with the manitou's and they are still fine. I have also up graded a couple of other things mainly for my preference and comfort. I swaped the tyres as the Kenda's did not suit the rooty local loops, I also put a WSD saddle on it and wider bars.

Hope this helps
Becks

Northwind

lovewales wrote:

they also offended me by telling me I didn't have a usual female body shape because I have short legs and long body :?

Don't worry, that's only usual for human females

pittpony

I have the 07 version. Its a very nice bike but the geometry is very race oriented. I ride a much more relaxed full sus most of the time now but still have the XTC for commuting and for when i want a blast at the local woods (its not very technical up there). I'll also use it for racing which I intend to try at some point. Overall its a great frame but with a fairly specific purpose.

FWIW i'm 5ft 8 and think i have a 17 inch frame (its a medium anyway)

strodey

You'll find the geometry good if your from a racey road backgraound, its aggresive!

easyg

Never had a carbon frame, but on ressearching it last year it seems that it is fine if its 'good' carbon as someone else said, and the reviews of the XTC have been decent over the years - I would always check the official reviews of bikes if poss (MBUK, What MTB etc), as well as ask on this forum, as the tests they do are pretty gruelling. Giant, like Scott for eg, is a good long standing manufacturer so its safe to say the carbon will be high quality.

At the end of the day, the force you would need to snap/ shatter that frame would prob break half the bones in your body anyway so being impailed on your beloved rig after a rotten landing will just mean you'll get to the hospital quicker in the ambulance!!