1. The most important thing about buying a new bike is to make sure it fits. The only way you'll know if the bike is right for you is to size up the bike and make sure that the bike's geometry matches your body's geometry. Ask questions and do some research.
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2. If possible, try to find a shop that will let you demo the bike on real dirt. Five minutes in a parking lot won't cut it. You wouldn't buy a car without a real world test drive, and a bike should be no different.
3. Don't belive the hype. Just because your favorite rider or best friend rides a certain bike, that doesn't mean that's the best one for you. Have an open mind and be realistic about your needs and ability.
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  1. #1
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    Is carbon bar supposed to dent a bit when installed?

    Hi all - apologies for the newbie question.
    I just got a carbon flat bar. I installed it tonight. It says max of 6Nm so I used 5.5Nm on my new clicky torque wrench.
    However, I noticed it kinda dented where the pressure point is of the stem.....
    Is this normal? Is it cracked?
    I have installed it back anyway and took it out for a ride in the park - locked the suspension and banged on the bars hard a few times and did some rough wheelies and dropped wheel down hard to see if there will be any play or something but didn't feel anything.









    Last edited by Muscleflex; 06-04-2013 at 01:16 AM.
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  2. #2
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    Did you go by the specifications on the Carbon bars or the specs on the stem? No, it shouldn't dent. It may be garbage now...

  3. #3
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    It says 6Nm on the bar
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  4. #4
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    that's not a torque problem. that's an uneven clamping surface problem. and yes, that's a problem for your bars. This is why I don't use carbon bars. you have to be real nitpicky about clamping surfaces, filing off edges and being super diligent about the WAY you tighten the stem faceplate to avoid compromising the bar the way you did there.

  5. #5
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    That looks damaged to me. You may wish to have a qualified person give their assessment.

  6. #6
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    Carbon bars often have a grippy coating around where the stem clamps and it is a little bit pliable. What you are seeing may just be that softer coating getting a little smooshed.

    However, it is hard to tell on the internet. I would have a shop look at it to be sure.
    15mm is a second-best solution to a problem that was already solved.

  7. #7
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    Thanks - I've put it back on the bike... but I used 5Nm this time... I've contacted the place I got it from to ask..

    by the way, how am I supposed to install it? Was I supposed to put heli tape or something before I put in the stem? My stem is smooth and I made sure all sides were the same when I was tightening with my torque wrench
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  8. #8
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    Quote Originally Posted by Muscleflex View Post
    by the way, how am I supposed to install it? Was I supposed to put heli tape or something before I put in the stem? My stem is smooth and I made sure all sides were the same when I was tightening with my torque wrench
    Maybe get a better stem that has more of a wrap around the bars? A lot of CF friendly stems are coming out with the most minimal of faceplate gaps and increased bar wrap rather than having the faceplate cover 50% of the bar and the stem the other 50%.

  9. #9
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    Quote Originally Posted by Muscleflex View Post
    Thanks - I've put it back on the bike... but I used 5Nm this time... I've contacted the place I got it from to ask..

    by the way, how am I supposed to install it? Was I supposed to put heli tape or something before I put in the stem? My stem is smooth and I made sure all sides were the same when I was tightening with my torque wrench
    Despite what I said above, I would not ride it unless you are sure it is not a dent or crack in the CF itself.
    15mm is a second-best solution to a problem that was already solved.

  10. #10
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    Quote Originally Posted by GTscoob View Post
    Maybe get a better stem that has more of a wrap around the bars? A lot of CF friendly stems are coming out with the most minimal of faceplate gaps and increased bar wrap rather than having the faceplate cover 50% of the bar and the stem the other 50%.
    Got a link to one of these? I'm trying to figure out how, if the clamp diameter matches the bar, you can have it wrap more than half way around the bar and still get the bar into the clamp. I know you could do that on older stems, but they were a bit more flexible, allowing you to slide the bar in from the side.
    15mm is a second-best solution to a problem that was already solved.

  11. #11
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    bike is the cannondale flash. the stem is an integrated something... don't know if I can use a different stem with the lefty fork?

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  12. #12
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    Ritchey has 260 degree wrap on their new WCS stems:
    Road Bike Stems - Ritchey Road Bicycle Stems

    I'm pretty sure Raceface stems I've had in the past have had more than 180 degrees of wrap. Thomson stems always clamp down with no gap so I'd imagine that makes for very uniform clamping.

  13. #13
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    As many horror stories that go around dont ride it until someone qualified can tell you its safe or normal. Carbon seems to be a very scary when failing material.

  14. #14
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    Can anyone tell me what Nm you guys use on your carbon bars? Did I got too much by using near 6Nm?
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  15. #15
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    Re: Is carbon bar supposed to dent a bit when installed?

    The torque should be determined by the stem. It may be written on the stem, or you may have to look it up.

  16. #16
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    Re: Is carbon bar supposed to dent a bit when installed?

    [QUOTE=Muscleflex;10441944]It says 6Nm on the bar [/QUOTE

    It says 6nm on the stem.

    Have you read the instructions from FSA on the installation of your handlebar? In the instructions it clearly states that the torque value stamped on your stem is the maximum allowable torque before one might expect bolt failure. It has nothing to do with the torque spec for your handlebar. In the manual it also states that final torque value for your carbon bar should be about 2 to 3 Newton meters. It seems you have torqued the bar two to three times over the recommended amount.

    Is this your bar?

    http://www.fullspeedahead.com/produc...Flat-Handlebar

  17. #17
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    Re: Is carbon bar supposed to dent a bit when installed?

    Quote Originally Posted by tnrider View Post
    The torque should be determined by the stem. It may be written on the stem, or you may have to look it up.
    Completely false... 100 percent inaccurate advice.. Not trying to be a prick just trying to make this clear

    The stem has no idea what type of handlebar you are installing. Steel, aluminum, carbon fiber, balsa wood. Each of these materials would require a different clamping force independent of the stem bolt maximum torque value.

  18. #18
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    Quote Originally Posted by Muscleflex View Post
    Can anyone tell me what Nm you guys use on your carbon bars? Did I got too much by using near 6Nm?
    6 Nm seems like it is too much. I usually put mine at 1.75Nm with carbon paste and see if it holds. If it does, great. If not I up it until it doesnt slip. My bars right now are just over 2Nm and are perfectly tight.

  19. #19
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    Quote Originally Posted by eatdrinkride View Post
    Completely false... 100 percent inaccurate advice.. Not trying to be a prick just trying to make this clear

    The stem has no idea what type of handlebar you are installing. Steel, aluminum, carbon fiber, balsa wood. Each of these materials would require a different clamping force independent of the stem bolt maximum torque value.
    Well my Easton EC70 handlebars came with instructions saying torque to the spec of the stem. My Stem is a syntace f109 which says up to 6nm, so I torque to 5 and have no issues in the last 9 months since installing.

  20. #20
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    Re: Is carbon bar supposed to dent a bit when installed?

    Quote Originally Posted by mbco1975 View Post
    Well my Easton EC70 handlebars came with instructions saying torque to the spec of the stem.


    Well my apologies then. I can't believe it actually says that maybe they're referring to the aluminum bar. At any rate it makes no sense as those values are bolt torque specifications values. And really have nothing to do with the clamping force needed of the handlebar. I think its just lazy instructions. 6nm is way too much for any carbon fiber bar I've owned. The idea really is too snugg it up just enough that they don't move. Around 2 to 3 mm.

  21. #21
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    Re: Is carbon bar supposed to dent a bit when installed?

    Quote Originally Posted by eatdrinkride View Post
    Completely false... 100 percent inaccurate advice.. Not trying to be a prick just trying to make this clear

    The stem has no idea what type of handlebar you are installing. Steel, aluminum, carbon fiber, balsa wood. Each of these materials would require a different clamping force independent of the stem bolt maximum torque value.
    Just checked the manual again for my s-works bar, it says to use the torque settings for the stem. I have installed all of my carbon bars this way, my LBS has also told me to use the torque values from the stem. I am guessing that I am not more than 50 percent incorrect.

    Sent from my SCH-I510 using Tapatalk 2

  22. #22
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    I find it hard to believe that the bar, at the center of it's largest diameter, the heartbeat of it's demand, is so whimpy as to crush like an egg from a possible 2x torque'in. I ponder, How much torque might I be applying throwing my body weight into it as I'm grabbing for dear life- Like mountain biking is sometimes? If I had to guess, it's not broken. Hope that turns out to be the case for you regardless. I agree with everyone else, better to have it checked than to guess and get hurt.

  23. #23
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    Re: Is carbon bar supposed to dent a bit when installed?

    Echoing above, is it just smooshy material?

  24. #24
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    Quote Originally Posted by eatdrinkride View Post

    It says 6nm on the stem.

    Have you read the instructions from FSA on the installation of your handlebar? In the instructions it clearly states that the torque value stamped on your stem is the maximum allowable torque before one might expect bolt failure. It has nothing to do with the torque spec for your handlebar. In the manual it also states that final torque value for your carbon bar should be about 2 to 3 Newton meters. It seems you have torqued the bar two to three times over the recommended amount.

    Is this your bar?

    K-Force Light Flat Handlebar
    yeah that's my bar... and no, I didn't read it. I just went straight away to install it remembering not to go over the 6Nm torque...
    so will 3 or 4 nm be enough on the bar (for next time?)
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  25. #25
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    Thanks all. I'll get it checked. I won't be using the bike for trails... until I get it checked.
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