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Putting the Squeeze on Exotic Materials

Discussion in 'Tech' started by Andrew Deane, Jun 10, 2008.

  1. Andrew Deane

    Andrew Deane Speeding Up

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    Torque Wrenches

    I recently became the proud new owner of a Specialized Roubaix Expert Ulegra Compact, my very first carbon-framed bike (plug: Super-comfortable no matter what the road surface dishes up!). After all the excitement died down, I learned that carbon frames are not so forgiving of a rough hand, and that certain bolts must be tightened to specific torque specifications (NM Newton meters or inch-pounds). Failure to comply could result in damage to the frame cosmetics, tube compaction, bolt shearing, and a rash of other potentially catastrophic failures.

    Before I dare tell my my wife I'll be spending more money on a new torque wrench (they are expensive little babies), I have a few questions that I hope you can help me with:

    How seriously should these precise torque recommendations be taken?

    How many of you own and use a torque wrench?

    If you own & use one, what is the make and model, and what is its range? (I noticed several styles and several ranges on the web).

    If I were to shell out a lot of cash for one, what range is the most universal / most useful? (e.g. Pedro's runs 2.3 - 22.6 Nm, Park Tool has two - 0 - 6.8 Nm and 0 - 67.8 Nm).

    What is the typical range on a typical carbon-framed bike?

    I'd appreciate any help in tightening down the answers.

  2. simon

    simon Speeding Up

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    Great post and questions!
    I tightened up my seat post to "pretty tight" but then it slipped down whilst riding.
    So I tightened it up some more, but I was approaching the "dam tight" on the feeling measure and was starting to worry.
    Anyway, please help answer the above thread, o' knowledgeable ones :)
  3. Philip

    Philip Speeding Up

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    Wrenching . . .

    There are SAE (and other) standards for torque values on bolts of a certain size & material going into a given material. These are the tables where the manufacturers are getting their torque values from. How seriously you take them depends on how seriously your wife would take being told you needed to buy a new frame :)
    I do and anyone who does work on my bike does too!
    Tohnichi MTQL 40N (N.m 5-40) motorcycle torque wrench
    The security bolts on brake pads are N.m 1.5. Most everyday bolts (handlebar / stem etc.) will be around N.m 5. The Dura-Ace 10 speed cassette is N.m 40. For me, the most useful range is N.m 5-40. Check the torque requirements for all the components (which you are prepared to work on) to understand your requirements.

    Don't forget you will need to buy the hex bits.


  4. Phil

    Phil Maximum Pace

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    Congrats on the bike, Andrew! I've always liked the Roubaix and almost bought one last year.

    Re: torque wrenches, I have this one:


    This is for low-end torque... For the heavy-end stuff, I just tighten has much as I can, or take it to the shop.

    Got the wrench mostly for the seat collar around my old carbon seatpost on the Specialized, but now I hardly ever use it. I'm always switching out stems and bars and should use it then, I suppose, but I'm too lazy to fish it out the toolbox when the hex key is already in hand...
  5. Polymer Head

    Polymer Head Warming-Up

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    Liked the comment from Philip...

    Let's look at how torque settings are calculated by considering the following

    1. Grades of materials, fastener
    2. Application: metal-to-metal contact, with seal, gasket...
    3. Bolt in insert
    4. With or without lubrication
    5. ... better stop

    Fortunately, it's only a few numbers for us to follow preventing damage to our expensive equipment and it's safe operation. Use the ranges as recommended first (at least during the guarantee period) and adjust if necessary. Whilst torque settings are important for all materials cracking a 'carbon' component is probably a common worry.

    Not the answer you're looking for but, we need the right tool for the right job, a torque wrench that covers the lower settings and one for the higher settings. For repeatable torque results use grease where required and apply torque to the nut when used with a bolt and washer.

    I'm getting back into cycling and need a torque wrench as well, so thanks for reminding me.

    For general reading try this
  6. Edogawakikkoman

    Edogawakikkoman Maximum Pace

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  7. TOM

    TOM Maximum Pace

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    Using carbon assembly compound gives peace of mind (to some extent)

    Saddle sinking into the frame can be really annoying but increasing torque may crack and eventually destroy the frame. Lately I have been using this wonderful product developed by Tacx...it really works on my bikes: carbon post in carbon frame + carbon post in titanium frame. I also apply it between my handlebar (carbon) and stem clamp (aluminium).

    Carbon assembly compound
    Reduces your tightening moment by 30%

    This unique assembly compound is composed in such a way that high-quality carbon, aluminium and saddle parts like seat-pin, pedals and handlebar stem can be assembled without difficulty. The adhesive effect allows you to reduce your tightening moment by 30%, so minimising damage! Dynamic assembly compound stops parts distorting or loosening and ensures perfect corrosion protection.

  8. simon

    simon Speeding Up

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    Thanks Tom,
    I'll be sure to have a look out for it!
    Do most good bike shop carry it?
  9. TOM

    TOM Maximum Pace

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    I believe so. I got mine at Friend Syokai in Nishikokubunji (the looks of the product were different than the product on the Tacx website: mine is a white pot with red lid and blue and gray label). Brands other than Tacx may be on the market too. Hope this carbon assembly compound works for you too. When you are using a brand-new seatpost or handlebar, you may have to apply the paste two or three times before it becomes fully effective.
  10. Polymer Head

    Polymer Head Warming-Up

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    ...seems the filling fell out the sandwich...

    Torque = force (N) x distance (m)

    Hence the SI units of newton meter

    Drat, misplaced my specs again.
  11. Sangetsu

    Sangetsu Warming-Up

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    My only experience with carbon frames was my old Kestrel. After a year of coastal humidity in Miami, the seat post became permanently stuck in the frame. Materials technology has improved somewhat, but I found that I prefer the ride of steel, and my last (counting in my head, 7...?) 7 bikes have been steel.

    Smaller fasteners should be very clean before torquing them, dirty threads can make as much as a 20% off of the true value. And make sure to use a quality torque wrench, if it says "Made in China", use it only on Chinese bikes.
  12. Philip

    Philip Speeding Up

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    That means 95% percent of bikes then :p:p:p (including mine).

  13. Wolfman

    Wolfman Speeding Up

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    Thanks for that tip Tom.

    I recently upgraded my post to a Thomson aluminium - it's lighter but has been slipping continuously in the ti frame. After reading this thread, today I went and got some stuff called Fiber Grip by Finish Line (1050 yen). It seems to have been made more with carbon fibre frames in mind but I guess (hope) it works to the same principle -it certainly feels like it has the same small balls inside the gel and has a kind of roughness to the touch.

    Will report back on progress.

    7th July Update:

    Took the bike out on saturday and experienced no slippage whatsoever. Worked a treat.:bike:

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