Carbon bars stem type

brindlescoops
brindlescoops Posts: 464
edited November 2012 in Road beginners
So.... I bought a bike recently with carbon bars and when i stripped it down to check everything, the stem had been overtightened and crushed the carbon bars, destroying them. I have a nice sparkly new set to fit, but wondered if you should use a specific type of stem to stop this happening again. The actual clamping force from the stem is across two thin bands in effect and I can help thinking that its a lot of force on carbon bars. I plan to use carbon paste and torque to 5Nm per bolt, will this be OK or am I risking wrecking another bar?
My biggest fear is that should I crash, burn and die, my Wife would sell my stuff based upon what I told her I paid for it.

Comments

  • just tighten it gradually, go for a ride if it moves tighten it..
    i would use this method as then you wont be over tightening it.
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  • You'll probably be fine at 3-4Nm, do it in stages (1/4 turn per bolt) so that you don't create pressure spots and see how it grips at below the max. You should be fine at 5 but some stem/bar combinations are a poor fit so less is good if it does the job.
  • 5nm is quite a common torque for carbon bars, stems and posts. All my Ritchey WCS stuff is 5nm, so I bought one of those handy Ritchey torque keys.
  • Grill
    Grill Posts: 5,610
    Keep in mind that when there is only one number published, as opposed to a range, it is the max torque spec. If you can get away with less then you should.
    English Cycles V3 | Cervelo P5 | Cervelo T4 | Trek Domane Koppenberg
  • All good advice thanks, i just wondered whether a stem with faces that cover the entire surface area under the clamp area would be a good idea, as it just seems you effectively have 2 bands of around 4 mm taking the entire clamping force, but if thats normal, then away I will go and fit them!
    My biggest fear is that should I crash, burn and die, my Wife would sell my stuff based upon what I told her I paid for it.
  • Grill
    Grill Posts: 5,610
    I use a Ritchey C260 stem. Not so much to protect my bars, but because it's light and stiff as hell. Go for it if you're that worried.
    English Cycles V3 | Cervelo P5 | Cervelo T4 | Trek Domane Koppenberg