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Old 09-29-06, 02:38 AM   #1
In Absentia
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Watch Out With Carbon Seatposts!





I'm pretty sure I just tightened the binder bolt way too much when I originally put it in. Last night I raised it up a bit and noticed that it seemed scored right where the collar was, so I pretty much expected this to happen. Fortunately I had another one in the garage and it broke right outside my house. Unfortunately I was already running late and this made me even later.

Also, it was a cheap ($25) post from Nashbar, so that might have something to do with it. Either way, if you have a carbon fibre seatpost, make sure you don't overtighten the binder bolt!
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Old 09-29-06, 07:56 AM   #2
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I will not use carbon fiber seatposts. I've seen too many instances of posts breaking here in BF. Plus, I like to hold my bike by the seatpost while on my work stand. Other than looking cool, I don't see much advantage to having one.
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Old 09-29-06, 08:09 AM   #3
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Maybe if your looking for some high zoot post maybe you could go with TI
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Old 09-29-06, 08:23 AM   #4
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Why even bother when there is Thomson.
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Old 09-29-06, 09:04 AM   #5
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My bike came standard with a carbon seatpost. All well and good except when you want to adjust the height without a torque wrenc.
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Old 09-29-06, 12:18 PM   #6
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Quote:
Originally Posted by ryanparrish
Maybe if your looking for some high zoot post maybe you could go with TI
I wasn't looking for anything fancy; I just bought it because it was only $25 and carbon posts are suppposed to give a smoother ride. I'm sure a $200+ carbon post would be a lot sturdier, but I don't see the point of spending that much money on a seatpost (for me).

I actually bought two of them, so I'm still using the same type of seatpost, but I only tightened the binder bolt until it's just tight instead of cranking it until I can't possibly tighten it anymore. I have nothing against carbon fiber seatposts in general, I think that you get what you pay for and you have to be more attentive if you're using one. Of course I was pretty lucky when mine broke: I heard and felt it starting to break and I knew beforehand that it was probably going to, so I was able to shift my weight forward and not fall. I've heard others' stories of crashing when their seatpost broke; I might be more anti-carbon if I were cleaning dirt out of road rash right now.
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Old 09-29-06, 01:58 PM   #7
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Unseen fractures are one of the problems with everything made- or supposed to be made, With Carbon Fibre. One hard knock- one bit of overtightening or even a lot of vibration can set up fractures that cannot be seen- but lead to sudden failure of the part. By getting one of the big name parts- with the big name price to go with it- you will have a guaranty that the part is made properly in the first place- but Cheap Carbon fibre bits are just a bit lower than carbon fibre bits to fit on my bike. And I used to be a fibre glass laminator.
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Old 09-29-06, 02:06 PM   #8
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I'm 220-230 riding the stock Bontrager cf seatpost that came on my Lemond Tourmalet. Have over 7000 miles on it without any problems.

I do remember last year on a century, a lady had a mionor crash. After she remounted the post snapped. Sucker was jagged and looked very dangerous. Good thing she didn't hit the post after it broke.

If my bike ever falls over or takes a dump, I'll be sure to replace the seat post!
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Old 09-29-06, 03:01 PM   #9
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Some CF seatposts are thick and some are sort of thin looking to me. I can't see what you've got there as far as thin versus thick. However, even for the thick CF posts (e.g., FSA, Alien) it is suggested that you should turn the collar 180 degrees so that the bolt is opposite the frame slot.
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Old 09-29-06, 03:08 PM   #10
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Quote:
Originally Posted by wagathon
, even for the thick CF posts (e.g., FSA, Alien) it is suggested that you should turn the collar 180 degrees so that the bolt is opposite the frame slot.

Is that right? I have a bud that got a new Specialized CF bike. He has the seat collar turned. I asked why it was like that but he didn't know. I just thought the assembler was a dork. He looked it up on the Specialized site and said all the bikes had the collar reversed.

I guess that prolly why they did it then?
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Old 09-29-06, 03:28 PM   #11
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Quote:
Originally Posted by barba
Why even bother when there is Thomson.
Exactly.
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Old 09-29-06, 03:57 PM   #12
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Exactly.
OK what is "Thomson?"

I happen to need a new seatpost and I don't want CF anything on my bike.
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Old 09-29-06, 03:59 PM   #13
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OK what is "Thomson?"

I happen to need a new seatpost and I don't want CF anything on my bike.
http://www.lhthomson.com/elite_features.htm
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Old 09-29-06, 04:15 PM   #14
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Originally Posted by barba
Why even bother when there is Thomson.
+1 I love my Thomson elite and I have no plans to upgrade it.

Some people say carbon seatposts can help dampen road vibrations, while I have never ridden one, I doubt they make that much of a difference. For the amount of broken CF seatposts I've seen, I'll stick with alum thanks.
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Old 09-29-06, 04:29 PM   #15
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I have a Tompson on my other roadie. I love the micro adjustment!
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Old 09-29-06, 04:46 PM   #16
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I can't say I've broken a carbon seatpost, but a few years ago I installed an Easton carbon fiber handlebar and seatpost. I'm still using the handlebar, but after one ride I returned the seatpost, too much flex for me. I remember wondering if the thing was going to snap, the flexiness was something I was just not going to be able to get used to. This was on a hardtail mountain bike, so the flexiness was probably more noticeable off-road than it would have been on a road bike. So anyway, I installed a Thomson soon after, and have been happy with it since. The carbon fiber handlebar is excellent, it flexes a little but isn't troubling to me like the seatpost was-
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Old 09-29-06, 05:07 PM   #17
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Quote:
Originally Posted by well biked
I can't say I've broken a carbon seatpost, but a few years ago I installed an Easton carbon fiber handlebar and seatpost. I'm still using the handlebar, but after one ride I returned the seatpost, too much flex for me. I remember wondering if the thing was going to snap, the flexiness was something I was just not going to be able to get used to. This was on a hardtail mountain bike, so the flexiness was probably more noticeable off-road than it would have been on a road bike. So anyway, I installed a Thomson soon after, and have been happy with it since. The carbon fiber handlebar is excellent, it flexes a little but isn't troubling to me like the seatpost was-
I'm a big rider so I don't know if it applies to you, but I read all the part descirtions when I can. I think I've read on Easton posts that there is a weight limit. Have seen osme down ot 160lbs.

Any thiong that posts a weight limit, I steer clear. Wheels,saddles,posts,frames etc.
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Old 09-29-06, 05:27 PM   #18
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Quote:
Originally Posted by Mr. Beanz
I'm a big rider so I don't know if it applies to you, but I read all the part descirtions when I can. I think I've read on Easton posts that there is a weight limit. Have seen osme down ot 160lbs.

Any thiong that posts a weight limit, I steer clear. Wheels,saddles,posts,frames etc.
I weighed about 170, I think, when I used that seatpost (I've put on a few pounds since then ), but of course on a mountain bike I had a lot of exposed seatpost, which would have exaggerated the flexiness of it. I had heard a lot of good things about the Easton seatposts, and for some folks I'm sure they're fine. But I just remember thinking almost immediately that there was no way I was ever going to feel confident or comfortable with that seatpost flexing like it was. And I agree, if there's a weight limit on something like that, it's a good idea to read the fine print, or stay away altogether-
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Old 09-29-06, 05:33 PM   #19
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Originally Posted by barba
Why even bother when there is Thomson.

My feelings exactly. I love my Thomson Elite....that thing is, in my opinion, seatpost perfection.
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Old 09-30-06, 02:02 AM   #20
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I don't trust carbon ANYTHING on a bike. I'd rather my bike weigh a few extra grams then have a material that shatters or breaks in half when it fails holding me up at 30MPH. steel/chromoly all the way.
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Old 09-30-06, 07:46 AM   #21
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Quote:
Originally Posted by Mr. Beanz
I'm 220-230 riding the stock Bontrager cf seatpost that came on my Lemond Tourmalet. Have over 7000 miles on it without any problems.

I do remember last year on a century, a lady had a mionor crash. After she remounted the post snapped. Sucker was jagged and looked very dangerous. Good thing she didn't hit the post after it broke.

If my bike ever falls over or takes a dump, I'll be sure to replace the seat post!
I'm pretty sure that the CF seatposts that come on treks that are <$2000 are just CF wrapped aluminum. I know the one on my cannondale r5000 is, and thats a 3500 dollar bike.
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Old 09-30-06, 08:30 AM   #22
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My carbon seat post gives me the creeps if I think about it too much. It seems like a core-sample waiting to happen.
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Old 09-30-06, 10:12 AM   #23
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So are they making this stuff like the import car addons? A single layer of decorative cloth buried in glue, oriented for appearance rather than structure?
Does anyone bother making these out of braided tow, so that it will collapse and fold rather than snap in half? The collapsed section would still cut like a razor if you ran your hand across it, but I'd rather have that than this kind of spontaneous saddle existence failure leaving a jagged spike...
A little aramid or aluminum where the post meets the frame wouldn't hurt anything, either.
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Old 09-30-06, 02:14 PM   #24
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Carbon Seatposts

Of course the other big issue with carbon seat posts is the inability to attached rear bags to them (like the KlickFix, etc.); these companies say that can lead to post failure (because of the clamp to tighten the holder).
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Old 09-30-06, 03:38 PM   #25
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it because it was only $25 and carbon posts are suppposed to give a smoother ride. I'm sure a $200+ carbon post would be a lot sturdier,
It has to be better right? It's 10x the cost! You overtightened it. End of story.
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