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  1. #1
    "THE RIDE IS MY CHURCH"
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    Carbon Stems vs Alloy Stems & Carbon Seat Post vs Alloy Seat Posts

    I'm looking to upgrade to something lighter and wanted input from those who know...

    I've read some people put some carbon road stems on their mtb bikes...
    Is carbon strong enough for this application, as I haven't seen manufacturers spec this on factory mtb bikes?

    I've have seen and read about many mtb bikes with carbon seat posts?
    Any comments about the pros and cons is welcome...

  2. #2
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    After having a carbon seatpost break after a small jump, I will never go back. Use a Thomson Elite or Masterpiece seatpost and forget about it.

    I have no experince with carbon stems, but again recommend only Thomson there.

  3. #3
    "THE RIDE IS MY CHURCH"
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    Quote Originally Posted by PB Matrix View Post
    After having a carbon seatpost break after a small jump, I will never go back. Use a Thomson Elite or Masterpiece seatpost and forget about it.

    I have no experince with carbon stems, but again recommend only Thomson there.
    That's exactly what I was worried about... Ability to withstand regular stuff...
    Can you say what model of seat post it was that broke?
    Was it expensive or not..I've seen prices from $70.00 to $200.00...

  4. #4
    Plays with tools
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    Quote Originally Posted by PB Matrix View Post
    After having a carbon seatpost break after a small jump, I will never go back. Use a Thomson Elite or Masterpiece seatpost and forget about it.

    I have no experince with carbon stems, but again recommend only Thomson there.
    Funny you should say that because every Thomson part I've owned (2 stems and a seatpost) have all broken. I did get what I would consider a reasonable life expectance out of them.

    I've never broken a carbon bar or post out of the dozen or so I've owned (easton, campagnolo, enve/edge and bontrager). Gram for gram the carbon parts are stronger. The thing I notice with my Enve carbon stem on my MTB (which is approved for off road use) is how much stiffer it is over the Thomson it replaced. It's not really much lighter but it feels way more solid.

  5. #5
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    If weight savings is your goal, carbon stems are usually heavier than their lighter Al counterparts (Extralight, Ritchey, Syntace). The same is usually true for seatposts.

    FWIW, I usually run carbon posts on hartails, and Thomson Masterpiece posts on dualies. I have no experience with carbon stems, but the only argument for them is increased stiffness, and I've never felt like I had a flexy stem, so...
    Tire Design & Development Engineer. The opinions expressed in this forum are solely my own.

  6. #6
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    Carbon stems are more for looks than weight savings.

  7. #7
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    TI stems and post for me.
    2014 S-Works Epic WC
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  8. #8
    dru
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    It is super easy to damage CF. That is why I stopped riding it.

    Drew
    occasional cyclist

  9. #9
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    Hard to believe someone has broken a Thomson stem or seat post, but I guess everything can break.

    Thomson for me, looks an feel plus made in USA - beautiful components. Just looking and feeling, fondling Thomson components I can tell there is some serious mojo going on!

  10. #10
    Missouri sucks...
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    The only cockpit stuff I use is Ritchey C260 stem, Thomson Masterpiece post and ENVE handlebars. You can't get any lighter without starting to worry about planting your face in the dirt

  11. #11
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    I had a friend running a (solid) carbon stem on a Trek Fuel and had it fail on him. (He took some lumps). he has since sworn off carbon stems for both mountain and road biking.

  12. #12
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    Quote Originally Posted by BacDoc View Post
    Hard to believe someone has broken a Thomson stem or seat post, but I guess everything can break.

    Thomson for me, looks an feel plus made in USA - beautiful components. Just looking and feeling, fondling Thomson components I can tell there is some serious mojo going on!
    Yeah, breaking one I can understand, but considering their reputation if all three break I start to wonder a bit.

    Their road stem faceplates crack when they're overtightened by even a smidge it seems, and there's plenty of reports of that on the web. I won't ride one for that reason. I've never damaged one of their mountain bike parts, ever.

    I'm a 300 pound muscular fatass that tacos wheels and breaks cranks.

  13. #13
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    Quote Originally Posted by BacDoc View Post
    Hard to believe someone has broken a Thomson stem or seat post, but I guess everything can break.

    Thomson for me, looks an feel plus made in USA - beautiful components. Just looking and feeling, fondling Thomson components I can tell there is some serious mojo going on!
    One of the stems was a face plate failure. Which they replaced for free even though it was several years outside of stated warranty. The other stem cracked on the outside corner of the stem body. It was cracked through to the threads. And the seatpost cracked right down the middle starting at the notch where the lower half of the clamp sits. All of these parts were at least 5 years old and the seatpost I've had since 99. I think Thomson makes some pretty respectable stuff. The reason I brought it up is that light parts will fail regardless of what they are made from. I'd much rather have a 100 gram carbon stem than an aluminum one!

  14. #14
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    Quote Originally Posted by customfab View Post
    All of these parts were at least 5 years old and the seatpost I've had since 99.
    Um, that is critically important information you should have added in your first post.

    The faceplate - yeah, they're known for that. Bad Thomson.
    The seatpost being what is it now, 12 years old? How many miles has it been ridden in that time?

  15. #15
    ballbuster
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    Yep, agreed.

    Carbon stems aren't any lighter than alu stems. I broke a Specialized Seatpost (that wasn't particularly light anyway) down the side by overtightening the seatpost clamp. My post kept sliding, even though the size was good, and I didn't tighten down the clamp that much. Nah, no carbon for those parts for me.

    Thompson stems... nice looking, but heavy and I know a guy who broke two of them... and he's not a heavy guy, or that much of a torque monster. They are nice and stiff, tho.

    I'm using FSA OS115 and RaceFace Deus stems right now. They are both lighter than Thompson stems, and way cheaper. The OS115 has a carbon faceplate.

    I've had mostly good luck with Sette parts. I've owned a few of the Sette APX seatposts and have had zero issues with them. They weigh in around 230 grams and sell for like $23. They use a two bolt style seat rail clamp.

    I did find a crack on my Sette Edge stem (135g, $25), so I stopped using it. However, I did EZ-Off it to silver and gave it a good mirror-like polish. I wonder if I polished off too much of the shot peening, and weakened it. That was the only stem I ever cracked... and it was a pretty tiny crack, like a 5mm visible edge.
    Last edited by pimpbot; 12-05-2011 at 12:18 AM.

  16. #16
    Trail Ninja
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    Syntace is a good brand to shop if you're going light. F109 stem + P6 seatpost are pretty reputable. Easton's stuff is pretty solid--I think their stuff is some of the most durable moderately lightweight parts going. No comment on Thomson, except that I'm selling all my Thomson stuff off.

    I have no experience with this stuff, but true weight weenies shop Extralite and KCNC. KCNC TI Pro lite seatpost 140g.

    I personally use a dropper post (Reverb) and a lightweight powdercoated CNC'd stem (Point 1 Split Second), but I'm very reluctant to recommend an anodized CNC'd part to anyone else. If I go carbon, I buy overbuilt carbon (stronger than alloy) over weight weenie carbon. IMO, CNC from billet alloy is a step back from forging and anodizing it can significantly reduce its fatigue light.

    Err, I mean 29er stems and posts are best. Niner only makes 29er stuff and they have seatposts and stems. A carbon seatpost and a forged stem. I can totally recommend them.
    Last edited by Varaxis; 12-04-2011 at 11:09 PM.

  17. #17
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    Quote Originally Posted by schnee View Post
    Um, that is critically important information you should have added in your first post.

    The faceplate - yeah, they're known for that. Bad Thomson.
    The seatpost being what is it now, 12 years old? How many miles has it been ridden in that time?
    I thought that the "a reasonable life expectance out of them" was for.

    The seat post is rather old and has a lot of miles. It was on my primary bike for 10 solid years. That bike has been retired since 09. Have no idea how many miles as I hate bike computers.

    I really don't have anything against Thomson and I have bought parts from them since the first three failed. I just threw that out there to displace the myth that light weight aluminum parts are some how impervious to failure.

  18. #18
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    Quote Originally Posted by customfab View Post
    ... The other stem cracked on the outside corner of the stem body. It was cracked through to the threads.

    ...I'd much rather have a 100 gram carbon stem than an aluminum one!
    How did you discover the crack? Creaking?

    I really try to get forged parts when I can. I figure at the minimum you need a certain amount of material to do the job, no matter what it's made of. Apply that to rims, stems, frames, spokes, etc. The lighter you go the shorter its life expectancy (in my mind anyway). I still can't see how something like a Loaded Precision stem at 100g will last as long as a Thomson at 190g.
    My current stem on my go to bike is 145g and it's not a Thomson, although I have them on 2 other bikes.
    And I can't get my mind past how a part functions in unusual conditions. Sure, everything works fine when JRA, but how does it work when you mess up, or when you ask it to do a little "extra", whatever that may be. The controlled chaos of MTBing suggests erring on the side of safety.
    Too light is too scary for me (I think that's a phobia I developed in the '90's).

    -F

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