Big difference in torque values for different stems?

bungle73
bungle73 Posts: 758
edited December 2018 in Workshop
Just gone from a cheap Brand X stem, that has a torque value for the steerer tube clamp of 9-10 Nm, to a Deda Superzero stem that has a torque value of just 5 Nm. Obviously two entirely different stem qualities, but still that is a HUGE difference. One has bolts on both sides, where as the other has them only one side, it that makes any difference?
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Comments

  • cooldad
    cooldad Posts: 32,599
    Nope.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

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  • bungle73
    bungle73 Posts: 758
    cooldad wrote:
    Nope.
    Nope? Nope what?
  • cooldad
    cooldad Posts: 32,599
    Nope to your question. The one with the question mark (?) at the end.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • jermas
    jermas Posts: 484
    Those torque figures are always the MAX torque for the component. If using on a carbon steerer use 5NM as the max with either stem. I normally use slightly lower than 5NM on all stems.
  • Vino'sGhost
    Vino'sGhost Posts: 4,129
    Why don’t you nip into your local bike shop bungle and ask them what they advise?
  • bungle73
    bungle73 Posts: 758
    cooldad wrote:
    Nope to your question. The one with the question mark (?) at the end.

    OK, thanks. But the post was a question in its entirety, ie why such a huge difference for components that are doing the same job?
  • bungle73
    bungle73 Posts: 758
    jermas wrote:
    Those torque figures are always the MAX torque for the component. If using on a carbon steerer use 5NM as the max with either stem. I normally use slightly lower than 5NM on all stems.

    It's an alloy steerer, but that isn't really important to the topic of this thread. As above, I'm wondering why the difference?
  • super_davo
    super_davo Posts: 1,128
    I definitely wouldn't want to torque a stem up to 10nm however many bolts it had. 5nm is plenty, particularly on a carbon steerer.
  • cooldad
    cooldad Posts: 32,599
    Bungle73 wrote:
    cooldad wrote:
    Nope to your question. The one with the question mark (?) at the end.

    OK, thanks. But the post was a question in its entirety, ie why such a huge difference for components that are doing the same job?

    No idea, I've never used a torque wrench on a bicycle. My fingers have always worked fine.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • jermas
    jermas Posts: 484
    As said above, the torque marked on the stem is the maximum the component can take, not an instruction on how to install it. The steerer is important because it's the steerer itself that determines maximum torque. The reason the Brand X stem might have a higher MAX torque figure is that it uses steel bolts (rather than stainless) which have a higher loading before snapping.
  • imposter2.0
    imposter2.0 Posts: 12,028
    jermas wrote:
    As said above, the torque marked on the stem is the maximum the component can take, not an instruction on how to install it. The steerer is important because it's the steerer itself that determines maximum torque. The reason the Brand X stem might have a higher MAX torque figure is that it uses steel bolts (rather than stainless) which have a higher loading before snapping.

    Most stem bolts are steel anyway, not stainless though, so I'm not sure if that answer makes complete sense or not. Brand X stems seem to recommend 9-12nm, which is significantly higher than most other stems. I can only guess that they may be lower tolerance or lower quality castings, so require a higher torque to achieve a good bond on the steerer. I doubt if it's anything to do with the torque loading of the bolts themselves.
  • jermas
    jermas Posts: 484
    Nearly all stems have stainless bolts.
  • imposter2.0
    imposter2.0 Posts: 12,028
    jermas wrote:
    Nearly all stems have stainless bolts.

    I have about 15 stems in the garage, some on bikes, some in the spares box. None of them was ever supplied new with stainless bolts.

    I think your claim that 'nearly all' stems have stainless bolts is not correct.
  • jermas
    jermas Posts: 484
    Are you sure they're not stainless? -shiny and silver.
  • imposter2.0
    imposter2.0 Posts: 12,028
    jermas wrote:
    Are you sure they're not stainless? -shiny and silver.

    Mate - all bolts are 'shiny and silver' when they're new, especially if they're plated. Stainless bolts will be marked on the bolt head as to what grade of stainless they are, such as 'A2-70' or similar. No marking = no stainless.
  • jermas
    jermas Posts: 484
    Mmm maybe think you need to think again! You must have some very rusty bike bolts!
  • imposter2.0
    imposter2.0 Posts: 12,028
    jermas wrote:
    Mmm maybe think you need to think again! You must have some very rusty bike bolts!

    Some of them are indeed very rusty. But you are the one claiming that 'nearly all' stem bolts are stainless, because they are 'shiny and silver'. Zinc or chrome plated bolts (which most of them are - not stainless) will obviously look shiny and silver' when new - and then they will go rusty if not looked after.

    Simply look on your 'shiny' stem bolts for the stainless markings and see for yourself.
  • jermas
    jermas Posts: 484
    Stainless can rust. Having work with bolts for 40 years I know what a stainless bolt is. Why you believe that every stainless bolt is stamped is beyond me.
  • imposter2.0
    imposter2.0 Posts: 12,028
    edited December 2018
    jermas wrote:
    Stainless can rust. Having work with bolts for 40 years I know what a stainless bolt is.

    Low grade stainless can have a lower chromium content, so may show minor signs of corrosion over time. But if you've worked with stainless for 40 years, you will presumably be familiar with the markings on stainless bolts. Your claim to 'know what a stainless bolt is' is certainly not validated by what you've written here...
    jermas wrote:
    Why you believe that every stainless bolt is stamped is beyond me.

    Clearly...
  • keef66
    keef66 Posts: 13,123
    Stem clamp and faceplate bolts on the Deda stem on my winter bike all went rusty. Replaced them with some stainless ones and so far, so shiny. Summer bike rarely gets wet, and it's original bolts are still sparkly.

    Tricky things to find like for like replacements for though. Some have tapered heads and some have tiny captive washers. It would make life easier if the stems were designed to take standard bolts / washers
  • jermas
    jermas Posts: 484
    Low grade stainless can have a lower chromium content, so may show minor signs of corrosion over time. But if you've worked with stainless for 40 years, you will presumably be familiar with the markings on stainless bolts. Your claim to 'know what a stainless bolt is' is certainly not validated by what you've written here...

    Low grade has nothing to do with it corroding. The type/grade of stainless determines this and other properties like hardness. NEARLY ALL BIKE BOLTS ARE STAINLESS! Your thoughts on bolts is nuts!

    The reason stainless bolts start rusting is often due to them being tightened and scuffed by steel tools (Iron contamination) .http://www.bssa.org.uk/topics.php?article=55
  • keef66
    keef66 Posts: 13,123
    I suppose because they generally thread directly into the stem, they are screws, not bolts.

    I'm off to check my Ebay bargain SS screws for identifying marks...
  • imposter2.0
    imposter2.0 Posts: 12,028
    jermas wrote:
    Low grade has nothing to do with it corroding. The type/grade of stainless determines this and other properties like hardness. NEARLY ALL BIKE BOLTS ARE STAINLESS! Your thoughts on bolts is nuts!

    The reason stainless bolts start rusting is often due to them being tightened and scuffed by steel tools (Iron contamination) .http://www.bssa.org.uk/topics.php?article=55

    Stainless steel still has an iron content, whether you like it or not. This can result in rust flecks appearing. But after 40 years of experience, you would know this already.

    You keep saying that 'nearly all bike bolts are stainless' but you provide no evidence to support this. You claiming it does not make it correct. Conventionally - and in my own experience - the majority of fasteners on a bicycle are steel, usually nickel/chrome-plated. This does not stop people from replacing them with s/s afterwards, as many do. Generally speaking, if a bolt is 'shiny and silver' (as you eloquently put it) it is most likely to be chrome, not stainless. Stainless is only 'shiny' once polished, so unless you are suggesting that all the bolts on a bicycle are routinely hand-polished before fitting, then you might need to think again.

    Anyway, this taken from a Q&A on whether to replace steel bolts with stainlness. Hopefully you might find it relevant...
    All Bolt Heads Will Have A Strength Code Or Reference Forged, Stamped Or Engraved On To Them For Identification. Any Bolt WITHOUT Markings Shall Be Considered To Be Of The Most Inferior Grade - Unless Its Composition Is Supported By Paperwork. Sometimes "Specials" Are Made By Turning Hex Bar, For Example.
  • jermas
    jermas Posts: 484
    Stainless steel still has an iron content, whether you like it or not
    When did I say they did not contain iron? The clue is in the name stainless STEEL!

    So according to your quote if the bolt isn't stamped it still could be stainless and if it has paperwork with it top quality stainless.
    So what you are saying is I'm correct that an unstamped bolt could be stainless. Because a bolt isn't stamped doesn't mean it's not stainless!!!!!!!
    Generally speaking, if a bolt is 'shiny and silver' (as you eloquently put it) it is most likely to be chrome, not stainless. Stainless is only 'shiny' once polished, so unless you are suggesting that all the bolts on a bicycle are routinely hand-polished before fitting, then you might need to think again.

    Stainless bolts can be highly polished or satin or matt. If polished, maybe they'd use large machinery (tumblers) and not polish each one by hand but i thought that would be obvious.
  • keezx
    keezx Posts: 1,322
    jermas wrote:

    1-Low grade has nothing to do with it corroding.
    The type/grade of stainless determines this and other properties like hardness. NEARLY ALL BIKE BOLTS ARE STAINLESS! Your thoughts on bolts is nuts!

    1-It does, lower grade usually means ferritic stainless steel (less nickel) and it corrodes easyer....
    Kitchen stuff is made from that.(cheaper)
    Tha vast majority of bike bolts are certainly not stainless.
  • jermas
    jermas Posts: 484
    http://www.wiggle.co.uk/ritchey-stem-stainless-steel-bolt-set-6-parts/

    Thats Ritchey for one using stainless^^^^.

    So Shimano bolts (shiny polished) on everything from derailleurs clamp bolts, crankset bolts, brake bolts etc etc etc aren't stainless?? Think again!!

    Finally nearly all silver bolts on a bike ARE stainless. Some black ones are stainless or plain steel. Different grades of stainless corrode/rust to different degrees.

    My knifes and forks are very shiny but also stainless steel. Cheap too!
  • Vino'sGhost
    Vino'sGhost Posts: 4,129
    Keef, here is a place for you to save

    https://www.pro-bolt.com bolts screws and nuts to your hearts content.

    peruse through there, its quality. BTW they have an ace little credit card sized metric thread gauge, i got one its worth having.
  • pinno
    pinno Posts: 51,316
    I'm afraid you are wrong jemas.

    Have a look at this:

    https://www.engineersedge.com/hex_bolt_ ... cation.htm

    ...or an even more extensive listing:

    http://www.americanfastener.com/astm-sa ... fasteners/

    There are many variants: hardness, stretch (look up Young's modulus of elasticity), grade.
    Just because Ritchey uses SS, it does not mean that all manufacturers use ss.
    I would suspect that as far as gruppo's are concerned, DA and Record/Super Record probably deploy a lot of ss and titanium but as you go down the tiers, they probably head towards plain old steel

    Here's a picture of my stem (on a Colnago - a good quality stem) but it's my winter bike:

    c5689c5e76e02bc10ecf82bfecad4ffb.jpg

    ...and here's the stem bolts on my Wilier. Another decent stem but it's my summer bike:

    fcddde8b9de60aae405417254cf0665e.jpg
    seanoconn - gruagach craic!
  • imposter2.0
    imposter2.0 Posts: 12,028
    jermas wrote:

    Not sure what point you are making with that link. That's a stainless steel bolt upgrade set. It only proves that Ritchey sells aftermarket stainless bolt sets. Ritchey also sells titanium bolt upgrade sets - but that doesn't prove anything either.


    jermas wrote:
    So Shimano bolts (shiny polished) on everything from derailleurs clamp bolts, crankset bolts, brake bolts etc etc etc aren't stainless?? Think again!!

    Finally nearly all silver bolts on a bike ARE stainless. Some black ones are stainless or plain steel. Different grades of stainless corrode/rust to different degrees.

    My knifes and forks are very shiny but also stainless steel. Cheap too!

    All you are proving here is that you don't know as much as you think you do. The majority of Shimano's fasteners - with some exceptions, I'm sure - are simply plated steel. No idea why you think that all 'silver' bolts on a bike are stainless. You still have not provided any evidence for this.
  • Vino'sGhost
    Vino'sGhost Posts: 4,129
    Imposter wrote:
    jermas wrote:

    Not sure what point you are making with that link. That's a stainless steel bolt upgrade set. It only proves that Ritchey sells aftermarket stainless bolt sets. Ritchey also sells titanium bolt upgrade sets - but that doesn't prove anything either.


    jermas wrote:
    So Shimano bolts (shiny polished) on everything from derailleurs clamp bolts, crankset bolts, brake bolts etc etc etc aren't stainless?? Think again!!

    Finally nearly all silver bolts on a bike ARE stainless. Some black ones are stainless or plain steel. Different grades of stainless corrode/rust to different degrees.

    My knifes and forks are very shiny but also stainless steel. Cheap too!

    All you are proving here is that you don't know as much as you think you do. The majority of Shimano's fasteners - with some exceptions, I'm sure - are simply plated steel. No idea why you think that all 'silver' bolts on a bike are stainless. You still have not provided any evidence for this.

    Imposters right you know