Carbon question.

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Mulger bill
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Carbon question.

Postby Mulger bill » Sun Sep 16, 2007 9:00 pm

Call me paranoid, but after the recent "debate" on carbon I decided to have a good look at my bits...

Anyway, take a look at this...
Image
Image

The marks are from the saddlebag rubbing the post, the top one shown seems to be very minor, more a surface blemish. The othere one is the worry, I can feel a definite, if small groove when running a thumbnail over the post.

Is this worth worrying about? Is there a new post on the immediate horizon? Do red bikes go faster? I've since slid a length of old tube onto the post to sit between the bag and post and crossed fingers.

Shaun.

not wanting another round of plastic/beercan badinage, can we stick to the component in question thanks


Oh yeah, theres about a quarter mile of post inside the frame. Bearing in mind insertion limits, would there be any dramas in taking a hacksaw to the last 70mm of post?

Thanks
Shaun
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Postby toolonglegs » Sun Sep 16, 2007 9:19 pm

Hard to say looking at the photo...personally (dont sue :wink: ) i would stop the problem happening and keep an eye on it and keep riding...dosen't look that bad.Cutting post well below the mark would be no prob but for 15-20grams why bother...just pee harder :shock: .
But you do have to be careful all the same with carbon,I kid you not but I have to take the rubber nipples off my new maxxis tyres as they CUT thru my front forks if I dont....but I havent replaced them!

MountGower

Postby MountGower » Sun Sep 16, 2007 9:23 pm

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Postby europa » Sun Sep 16, 2007 9:30 pm

I wouldn't be too concerned about that Shaun. You've only worn away a bit of the resin. If it had gone deeper and started cutting the fibres, I'd toss it.

As mentioned by others, the big problem with carbon is the knock that's heavy enough to start a fracture, with nothing being visible (the old starting from the inside out routine).

Live with the thing, though you are right to prevent further damage. Ride happy and if it bothers you, put an ally post in - it'll cost you a poofteenth of a millenothing up every hill you climb but some of us are happy to live with that.

Richard
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Postby toolonglegs » Sun Sep 16, 2007 9:31 pm

MountGower wrote:From what I have read here and elsewhere, this sudden failure bizzo is usually an inside out job. I'm not sure small rub marks have been accused of anything that I've read about. I'd be more worried if the bike fell over and hit the seat post.

For me, I am obviously one of the more anti corbon people you will ever meet so you should bare that in mind when I say that I trust carbon seat posts and forks less than I trust the frames for reasons that won't boggle the mind too much.

I think if you trust carbon fibre you need to dismiss what people say against it and go with those feelings. If what you have read or seen lately is causing you preoccupation while you are riding, get rid of it. I have an aluminium seat post and steel forks. Somehow the blokes who had no choice seemed to put up with it, if indeed putting up with something that just isn't a problem is the right choice of words.
I have an alloy post....but steel forks....OMGosh :shock:

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Postby triode12 » Sun Sep 16, 2007 9:43 pm

More often than not, these "carbon" seat posts are really aluminium posts with a carbon outer wrap. i.e. The carbon is there only for cosmetic reasons. 8)

Check the inside of the tube to see if this is the case.
Last edited by triode12 on Sun Sep 16, 2007 9:45 pm, edited 1 time in total.

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Postby triode12 » Sun Sep 16, 2007 9:44 pm

toolonglegs wrote:
MountGower wrote:From what I have read here and elsewhere, this sudden failure bizzo is usually an inside out job. I'm not sure small rub marks have been accused of anything that I've read about. I'd be more worried if the bike fell over and hit the seat post.

For me, I am obviously one of the more anti corbon people you will ever meet so you should bare that in mind when I say that I trust carbon seat posts and forks less than I trust the frames for reasons that won't boggle the mind too much.

I think if you trust carbon fibre you need to dismiss what people say against it and go with those feelings. If what you have read or seen lately is causing you preoccupation while you are riding, get rid of it. I have an aluminium seat post and steel forks. Somehow the blokes who had no choice seemed to put up with it, if indeed putting up with something that just isn't a problem is the right choice of words.
I have an alloy post....but steel forks....OMGosh :shock:
Lugged steel forks can be as or more comfortable as carbon ones.

ggundersen

Postby ggundersen » Sun Sep 16, 2007 9:48 pm

I can remember in the old days fixing bikes that had a wooden stick jammed in their steel forks - just in case the forks should snap. I surpose if your paranoid you could do the same with your seat post?????

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Postby europa » Sun Sep 16, 2007 9:59 pm

ggundersen wrote:I can remember in the old days fixing bikes that had a wooden stick jammed in their steel forks - just in case the forks should snap. I surpose if your paranoid you could do the same with your seat post?????
Taking this far more seriously that you probably intended :D (hey, this is a forum, it's traditional :roll: ), but I'd have thought that would be the wrong move. A carbon seatpost is designed to work as a tube and so, filling the gut with timber would remove its ability to flex and lead to some other form of failure ... wouldn't it?

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Postby toolonglegs » Mon Sep 17, 2007 5:53 am

I wouldn't worry too much :shock: although going to steel forks may be a bit over the top :roll:
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Postby Mulger bill » Mon Sep 17, 2007 7:26 pm

triode12 wrote:More often than not, these "carbon" seat posts are really aluminium posts with a carbon outer wrap. i.e. The carbon is there only for cosmetic reasons. 8)

Check the inside of the tube to see if this is the case.
Yeah, heard about that scam, 'tis all good.

Think I'll keep going as is and keep a very close eye on it. Gonna be an awkward riding position, but what the... :wink:

Shaun
...whatever the road rules, self-preservation is the absolute priority for a cyclist when mixing it with motorised traffic.
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Postby Bnej » Mon Sep 17, 2007 8:11 pm

Most likely, it's just scuffing away the clear coat over the structural parts. If you run a cloth over it and it snags, or if you see little fibres popping out, or you get creaking/popping noises, then start worrying.

But it's probably just surface damage and nothing to worry about. If these things could be destroyed by a seat bag it'd be happening all the time. ;)

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Postby toolonglegs » Mon Sep 17, 2007 9:47 pm

at 3.35 kilos...it will never break :wink:


Image

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Postby gsxrboy » Mon Sep 17, 2007 10:35 pm

Do you have any more info on that bike longlegs? I can't fid a page anywhere for some reasons! just for interests sake. Cheers :)

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Postby toolonglegs » Mon Sep 17, 2007 10:44 pm

gsxrboy wrote:Do you have any more info on that bike longlegs? I can't fid a page anywhere for some reasons! just for interests sake. Cheers :)
It is on cycling news...eorbike wrap up part 10 :D ...i love toys,wish i had the money to fund my habit!.
http://www.cyclingnews.com/tech/2007/sh ... robike0710

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Postby europa » Mon Sep 17, 2007 10:46 pm

toolonglegs wrote:.i love toys,wish i had the money to fund my habit!.
You'll never have enough money - the habit just gets bigger to compensate :roll:

Richard
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Postby gsxrboy » Mon Sep 17, 2007 10:48 pm

Thanks oh legged to the max wise one.

*goes to read*

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Postby toolonglegs » Mon Sep 17, 2007 10:50 pm

europa wrote:
toolonglegs wrote:.i love toys,wish i had the money to fund my habit!.
You'll never have enough money - the habit just gets bigger to compensate :roll:

Richard
mmmm...tell me something I don't know!!! :lol: I only want 3 mtb's...super light hard tail,light xcountry dualie and a down hiller,2 track bikes...sprint and tt,plus a road tt bike,I actually have the road bike I want but a set of zipp 440 clydesdale's wouldn't go a miss,oh I also like my training bike....
going to bed to dream of unrealistic things :roll:

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Postby inaminit » Mon Sep 17, 2007 11:06 pm

I think there has been enough sound advice to help mulger out with his seat post concerns, but noone has even attempted to address the most important question he posed in the OP.....

Do red bikes go faster?

Of course they do, at least I hope they do as I own 2 of them :lol: :lol:
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Postby triode12 » Wed Sep 19, 2007 9:59 am

A former Boeing engineer says that Carbon shatters on impact and should not be used on the new 787.

http://www.news.com.au/travel/story/0,2 ... 77,00.html

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Postby europa » Wed Sep 19, 2007 11:00 am

triode12 wrote:A former Boeing engineer says that Carbon shatters on impact and should not be used on the new 787.

http://www.news.com.au/travel/story/0,2 ... 77,00.html
Maybe they shouldn't go crashing them :roll:

Interesting story though.

Richard :D
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Postby mikesbytes » Wed Sep 19, 2007 12:06 pm

So I shouldn't have a CF bike because it wouldn't survive a lighting strike.

Jokes aside, it seems that while CF is the strongest readily avail material, when it does break it tends to shatter. I've not had a single problem with the carbon forks and seat post I've got.

My conclusion on CF is that you should buy good quality CF components. Like any material there is the good the bad and the ugly.
If the R-1 rule is broken, what happens to N+1?

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Postby europa » Wed Sep 19, 2007 12:11 pm

mikesbytes wrote:So I shouldn't have a CF bike because it wouldn't survive a lighting strike.

Jokes aside, it seems that while CF is the strongest readily avail material, when it does break it tends to shatter. I've not had a single problem with the carbon forks and seat post I've got.

My conclusion on CF is that you should buy good quality CF components. Like any material there is the good the bad and the ugly.
Spot on mate - cf has its place. We tend to forget that when we say 'steel' we mean good steel, not the old water pipe jobs and bad TIG welding can produce weak joints in steel frames.

To be honest, if lightening took me out, the last thing I'd be thinking about would be the bike. Wonder what a lightening bolt would do to a steel frame. Surely it wouldn't be good for it - messing up the temper and stuff like that. Any engineers here willing to hazard a guess?

Richard
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Postby Aushiker » Wed Sep 19, 2007 12:29 pm

mikesbytes wrote:So I shouldn't have a CF bike because it wouldn't survive a lighting strike.
I have been in an Airbus 330 which was struck by lightening (my last flight out of Singapore). Bloody loud bang for sure. No idea about the carbon content but.

Andrew

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Postby triode12 » Wed Sep 19, 2007 1:34 pm

I think the thing to take away from that article and what Buzz has posted is that when carbon fails it does so catatrosphically.

You might own a well built frame, but if the inherent characteristic of the material is to shatter on impact, one cannot be certain how and when it will fail (if it does at all) after the frame has suffered a hit from a crash or fall.

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