Importance of proper torque and torque wrench?- Mtbr.com
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  1. #1
    SNOW BABY!!!
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    Importance of proper torque and torque wrench?

    Is it that important to set bolts and nuts at proper torque settings with a torque wrench or is tightening bolts/nuts reasonably tight with regular wrench/tools enough?

    Maybe it's part dependent? Say maybe proper torque is more important for suspension joints...etc and less so for pedals, shifters? Or it doesn't really matter?

    Thanks.

  2. #2
    dru
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    It depends

    It all depends on criticality and 'feel'. How good a wrench are you? I have been stripping bolts for the better part of 3 decades so I have a really good idea of how tight too tight is. Feel is especially crucial with steel hardware threaded into aluminum. If it is something like crown bolts or cranks I would use a torque wrench. I have two BTW.

    I have blown stuff up by incorrectly torqing stuff, even with a t. wrench. I blew up my Gamma because of an air leak simply because I didn't remove oxidation from the threads in the case halves. The oxidation binds to the bolts a little when tightening giving an erroneous higher torque reading than actual. Result-boom! A good mechanic learns from his/her mistakes. In this case chase the block threads with a tap, and the bolts with a die.

    It is important to have things correctly tight on a bicycle too.

    Drew

  3. #3
    thecentralscrutinizer
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    Torque is fairly important in most applications.

    Simply put, not enough torque can allow the part to loosen, to much can stress the metals and cause premature failure of the parts.
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  4. #4
    Enthusiast
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    I'll ask a related question then: where do I find correct torque numbers for the different bolts on my bikes? If I wanted to know the correct torque for, say, a water-bottle bolt, or for a stem bolt, where would I look? Sadly, none of that useful information is in the manuals for my bikes.

  5. #5
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    You can find torque values here http://www.parktool.com/repair/readhowto.asp?id=88

    While proper torque is important, most people go by feel, unless it is a very important part. I think the older parts such as square taper cranks and bottom brackets could get away by feel. The newer outboard bearing bb seem more sensitive. Same can be said for Thomson stems, the stem cap on my bike cracked due to improper and uneven torque.

    With that said, a breaker bar has no business anywhere near a bike.

  6. #6
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    A lot of components have the torque values etched or painted on them or in their individual manuals when bought aftermarket, component websites are also a good source.

    And with anything light or carbon unless you can buy another one get out the torque wrench. If two components have different torque values for the same interface like a stem says 50 inch pounds and a bar says 40 inch pounds always use the lower value.

  7. #7

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    Quote Originally Posted by rallyraid

    With that said, a breaker bar has no business anywhere near a bike.

    ...Except if using it to remove an ACS freewheel

  8. #8
    T , V , & K Rider
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    I have a tendency to over torque so for me using a torque wrench is very necessary ! Lets face it most aluminum alloy or carbon components do not require alot of torque and can easily be damaged or overstressed by to much torque and since I like to use high quality components on my bikes I can't afford to ruin them by trying to guess the right torque by feel ! TIG.

  9. #9

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    For anything carbon based, it's a must. For metal based, you can get away with a bit more in a pinch, if you've a fair idea of what you're doing, but I'd really advise you spending the time to get it right.

    I'd advise heavily if you only want to check some of the bolts to ensure the stem bolts, seat post clamp & saddle rail bolts, brake rotor for disk/mount bolts, and crank bolts are to spec. The rest isn't so critical, at least if all those stay on tight should something else go wrong you can stop safely. (And of course make sure your pedals are actually done up nice and tight to your cranks - saw that go wrong once, not good).

  10. #10
    Where is my mind?
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    How expensive is the part you're trying to...."screw." Sorry I tried to avoid the pun. Essentially, if it's more expensive then a torque wrench, get the wrench.
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  11. #11
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    more often than not, i can go by feel. the more you do it, the better you get. i have stripped stuff do to over-torquing though. live an learn.
    When under pressure, your level of performance will sink to your level of preparation.

  12. #12

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    Learn from my mistakes and be careful if you're dealing with aluminum and dissimilar metals, I would use a torque wrench mainly in those cases.

    Proper torque when dealing with aluminum mating to other surfaces is critical cause after time goes by and some rust builds up on the other metal the alumnum threads actually become the weak link and they rip right out rendering the aluminum part useless.

  13. #13
    Vaginatarian
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    torqueing is very important, and not doing it can come back to haunt you later.
    when you tighten a bolt or nut the specified torque is calculated to get the maximum performance . as you tighten the parts the elasticity of the metals allows the threads mesh & tighten completely, overtighten, and the metal weakens and stretches , you might not notice anything right away, but its weaker and could possibly strip or snap. Under tighten and things tend to come apart.
    One more caveat, sometimes the torque spec. requires lubed threads to be accurate, sometimes clean & dry.
    on my bike I torque, stem, controls, brakes, BB, all suspension mounts & bearings, 20mm axle and pinch bolts
    youd be surprised how many creaks dissapear when parts are cleaned and properly torqued.
    I dont torque pedals, they wont unscrew (reverse thread) and I find it alot easier to remove them when I havent cranked them on to hard

  14. #14
    i also unicycle
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    it's most crucial on carbon parts where you can damage the carbon fairly easily by getting it too tight. sometimes components come with a little too light of torque spec. some customers of mine have had problems with campy and sram road cranks coming loose, and when pressed both companies said to add a bit more torque and it should be fine, 10% or so.
    mtbr says you should know: i work in a bike shop.
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