carbon bars

nasha48
nasha48 Posts: 231
edited December 2016 in MTB general
Quick question to make sure - there's no problem with fitting carbon bars to an aluminium stem is there?

Comments

  • cooldad
    cooldad Posts: 32,599
    Nope just don't do the bolts up like a musclebound gorilla.

    Most people use an aluminium stem anyway.
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  • Hinaultscrapcousin
    Hinaultscrapcousin Posts: 647
    Nope. Torque the stem properly and you might need some anti-slip paste in there and it'll be fine. You'll need some kind of paste/grease in there anyway as you can get galvanic corrosion.
  • rockmonkeysc
    rockmonkeysc Posts: 14,774
    Galvanic corrosion happens between two different metals. How's it going to happen to carbon bars?
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  • cooldad
    cooldad Posts: 32,599
    Because carbon can carry a current.

    http://ma.ecsdl.org/content/MA2013-02/19/1765.full.pdf
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  • Hinaultscrapcousin
    Hinaultscrapcousin Posts: 647
    RockmonkeySC wrote:
    Galvanic corrosion happens between two different metals. How's it going to happen to carbon bars?
    Because chemistry. Happens a lot the carbon seatposts in aluminium frames.
  • midgehulluk
    midgehulluk Posts: 195
    Hinaultscrapcousin wrote:
    RockmonkeySC wrote:
    Galvanic corrosion happens between two different metals. How's it going to happen to carbon bars?
    Because chemistry. Happens a lot the carbon seatposts in aluminium frames.

    daft question, can this happen the other way round???? where should you put carbon paste?
  • Hinaultscrapcousin
    Hinaultscrapcousin Posts: 647
    midgehulluk wrote:
    Hinaultscrapcousin wrote:
    RockmonkeySC wrote:
    Galvanic corrosion happens between two different metals. How's it going to happen to carbon bars?
    Because chemistry. Happens a lot the carbon seatposts in aluminium frames.

    daft question, can this happen the other way round???? where should you put carbon paste?

    I'm not sure what you mean by the other way round? Do you mean an Alu post in a carbon frame?
  • Monty Dog
    Monty Dog Posts: 20,614
    Galvanic corrosion generally a worse problem with carbon seatpost and alloy frames because the seattube gets reamed for size and you have bare metal contact - made worse by exposure to water. Most stems an anodised and this help prevent corrosion but assembly paste is still a good idea as it provides additional friction / corrosion inhibiter.
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  • rockmonkeysc
    rockmonkeysc Posts: 14,774
    Hinaultscrapcousin wrote:
    RockmonkeySC wrote:
    Galvanic corrosion happens between two different metals. How's it going to happen to carbon bars?
    Because chemistry. Happens a lot the carbon seatposts in aluminium frames.

    Well I never knew that. I know carbon will carry a current but I always assumed that the resin in carbon fibre would prevent galvanic corrosion.
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  • nasha48
    nasha48 Posts: 231
    Well then, appreciate all this - this is why I asked as I just wasn't sure of the chemistry bit. I'll proceed and use some paste. Cheers guys.
  • Hinaultscrapcousin
    Hinaultscrapcousin Posts: 647
    RockmonkeySC wrote:
    Hinaultscrapcousin wrote:
    RockmonkeySC wrote:
    Galvanic corrosion happens between two different metals. How's it going to happen to carbon bars?
    Because chemistry. Happens a lot the carbon seatposts in aluminium frames.

    Well I never knew that. I know carbon will carry a current but I always assumed that the resin in carbon fibre would prevent galvanic corrosion.

    As Monty Dog said it happens more at the seatpost/seat tube interface as it requires contact of the conducting materials via an electrolyte (aluminium forms a tough oxide layer which usually stops it, but when this is scratched, which is fairly easy sliding seatposts in and out of frames, it will happen) and with hard anodised, narrow contact points on stems it's less likely at the stem/handlebars but still possible.
  • keef66
    keef66 Posts: 13,123
    I have both a carbon post in an alloy frame and an alloy post in a carbon frame, and use carbon assembly paste on both. Partly to deter corrosion and partly to stop them slipping.
  • midgehulluk
    midgehulluk Posts: 195
    Hinaultscrapcousin wrote:
    midgehulluk wrote:
    Hinaultscrapcousin wrote:
    RockmonkeySC wrote:
    Galvanic corrosion happens between two different metals. How's it going to happen to carbon bars?
    Because chemistry. Happens a lot the carbon seatposts in aluminium frames.

    daft question, can this happen the other way round???? where should you put carbon paste?

    I'm not sure what you mean by the other way round? Do you mean an Alu post in a carbon frame?

    Yeah, I've got carbon frame with Alu post. I never knew about this galvanic corrosion. Best get some paste on it, is assembly paste the same as carbon paste ?
  • eric_draven
    eric_draven Posts: 1,192
    I have just put some carbon Cromags on my Scout,and they come with a rough texture around the clamping area,as if you don't use paste with them
  • Giraffoto
    Giraffoto Posts: 2,078
    eric draven wrote:
    I have just put some carbon Cromags on my Scout,and they come with a rough texture around the clamping area,as if you don't use paste with them

    Renthal do the same neat trick, and I can confirm you don't need paste with them.
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