Proper torque w/o a torque wrench
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  1. #1

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    Proper torque w/o a torque wrench

    I succeed in ruining a nice set of handlebars (alu, not carbon) on my road bike b/c I tightened the bolts too hard. The bar now has a permanent depression in it and signs of stress-cracks.

    How do I avoid this in the future? Is there a way to be certain that torque is not too severe without the use of a torque wrench? I am working with alu stem/bar, here.

    Thanks.

  2. #2
    NeoRetroGrouch
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    Quote Originally Posted by Supersonic
    I succeed in ruining a nice set of handlebars (alu, not carbon) on my road bike b/c I tightened the bolts too hard. The bar now has a permanent depression in it and signs of stress-cracks.

    How do I avoid this in the future? Is there a way to be certain that torque is not too severe without the use of a torque wrench? I am working with alu stem/bar, here.

    Thanks.
    Find the required torque in inch-lbs. Measure the number of inches from the center of the bolt to the center of where you are holding the wrench. Divide the torque required by the distance from the center of the bolt. Apply what you think is that many lbs.

    One step further: Set up so that you are pushing straight down on the above wrench. Stand on a bathroom scale and push down until your 'weight' decreases by the required lbs.

    TF
    "Don't those guys know they're old?!!"
    Me, off the back, at my first 50+ road race.

  3. #3

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    I'll paraphrase Turbo's answer:

    10 ft/lbs means 10 pounds of force on the end of a foot long wrench. I think that most people can estimate pretty closely if they think it through that way.

  4. #4
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    get a torque wrench...

    Buying a torque wrench would have been cheaper than the bars you ruined. All you need is a basic beam type, with the proper range.

    http://www.excelsports.com/new.asp?p...ajor=6&minor=6

    After you properly torque some of the M5 and M6 bolts with the torque wrench, loosen them by hand, then retighten and check the torque with the torque wrench, to get a feel for this torque range. Then you can perform on the road adjustments without damaging the bike.

    Using a 4-5-6mm Y-style hex wrench or only short-handle hex wrenches will also reduce the possibility of over-torqueing. Using the Y-style wrench a modest twist will adequately tighten M5 or M6 bolts.

    http://www.excelsports.com/new.asp?p...ajor=6&minor=3

  5. #5

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    Riddle me this

    OK, excuse what is probably an idiotic question, but how would you use one of those torque wrenches to tighten a little hex head bolt like the ones on a handlebar? Is there an adapter to hold the hex head wrench?

  6. #6

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    good question

    Quote Originally Posted by CNY rider
    OK, excuse what is probably an idiotic question, but how would you use one of those torque wrenches to tighten a little hex head bolt like the ones on a handlebar? Is there an adapter to hold the hex head wrench?
    was wondering the same thing!

    will probqably pick up a torque wrench, tho.

  7. #7
    NeoRetroGrouch
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    Quote Originally Posted by CNY rider
    OK, excuse what is probably an idiotic question, but how would you use one of those torque wrenches to tighten a little hex head bolt like the ones on a handlebar? Is there an adapter to hold the hex head wrench?
    You get one of these that fits your hex bolt and the socket of your torque wrench. - TF
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  8. #8

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    Sears sells the Craftsman sets rather cheaply. They work quite well.

    Their site was hanging, but the set should be at: http://www.google.com/url?sa=X&oi=fr...wsYAAAAAAAAAAA

    Still hanging, but here's a cached version of the page, just in case:

    http://66.102.7.104/search?q=cache:L...ient=firefox-a

  9. #9
    Travels by Map
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    I just bought the Park torque wrench that C-40 linked to along with my new wheels a couple of weeks ago. Since I knew I would move my cassette from the old rear wheel to the new one, I wanted to be able to tighten the lockring correctly.

    Now that I've used it once, I've already justified the expense rather than having broken parts or improper tightening that could lead to some kind of incident while riding. It's worth the money.

  10. #10
    uhhhh, what?
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    Quote Originally Posted by Supersonic
    How do I avoid this in the future? Is there a way to be certain that torque is not too severe without the use of a torque wrench? I am working with alu stem/bar, here.

    Thanks.
    easy, tighten it until it snaps, then back off a 1/4 turn...

    kidding, that's just my standard smartass answer.

    in reality, i'm a compulsive torque wrench collector. inch/ounce, inch/pound, newton/meter, foot/pound, dials, beams, clickers, you name it i've probably got it.

    for bicycles you need a pair; inch/pound and foot/pound. beam style are the most affordable, and work just fine.
    plus a change, plus c'est la m'me chose - alphonse karr

  11. #11

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    Used to say I didn't need a torque wrench, but...

    I've taken pride in doing all my own work (except wheelbuilding) for more than 20 years, and I never needed any sissy torque wrench. When my dad died, there was one in his stuff and I took it home and, just for fun, checked the torque on a bunch of bikes I'd built by feel. I was all over the place, way high on some, low on others, no pattern at all. I'm a convert. It's just a cheap Craftsman beam model, nothing fancy, but it's consistent and repeatable and well worth having.

  12. #12
    zac
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    Ok you guys have me thinking. I have never used a torque wrench and have been wrenching my rides for years. But my latest ride has alot of CF hanging on it. I actually have several torque wrenches (both inch-lbs and its bigger cousin N-m / ft-lbs).


    But for the life of me, were the heck do you find the torque specs for the various components. For instance, I flipped my stem and bumped it down a spacer. Now the cap bolt is easy to do, but what are/should be/or where can I find the torque specs for a Bonty stem? both at the bars (aluminum Bontys) and at the steerer tube (Bonty XXX lite forks) ??

    Thanks in advance
    zac


    BTW, I checked at bontrager.com and found nothing.
    Also the "manual" that came with my 05 Trek is a pitiful 10 pages or so, and has none of this info. I have DL'd the Trek 2004 manual and notice that is has torque specs in it, but they are generic, and I couldn't find a 2005 manual on Treks site!

  13. #13
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    Typical & similar torque settings can be used from other brands of components. try Cannondale's site. Their service PDFs contain loads of torque values as do many of the Shimano service PDFs.
    Last edited by HAL9000; 10-27-2005 at 09:27 AM. Reason: From not form
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  14. #14
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    general guidelines...

    There are some general guidelines for the common M5 and M6 bolts on bikes. 5-6Nm is generally safe for M5 bolts and 9-10Nm is safe for M6. Thes are not maximum values. Better to stay on the lower side and tighten more only if something slips.

    50Nm is common for bottom brackets and cassette lockrings.

    Most stems and seatposts come with instructions that include the recommended bolt torque. Other items, like cassette lock rings have and bottom brackets most often have the torque written on them.

    Personally, I never use a torque wrench on small bolts because most are holding items that get adjusted on the road. You can't take that torque wrench with you.

    http://www.boltdepot.com/fastener-in...ed-Torque.aspx

  15. #15
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    Retighten as many turns as you loosen

    [QUOTE=C-40]
    Personally, I never use a torque wrench on small bolts because most are holding items that get adjusted on the road. You can't take that torque wrench with you.
    QUOTE]

    I always assumed that I could return a bolt to the same torque if I retighten it the same number of turns that I loosened it. I always start with the allen wrench sticking up and then count the number of full turns that I loosen it. Then, when retightening, I simply do the reverse.

    This assumes that I can remember the number of turns after I skin my knuckles and drop the wrench a couple times. ;)

  16. #16
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    Note of caution on using torque wrenches

    One often overlooked aspect of using a torque wrench in assembling a joint is the control and repeatability of all the factors that affect friction and the stretch of the bolt. In working on bikes, this is normally the presence or absence of things like grease or thread compound on mating surfaces, including washers and the underside of the head of the bolt. The real objective is to stretch the bolt to obtain sufficient tension in the joint. The amount of torque to do this can vary widely between degreased surfaces and those greased and/or dirty.

  17. #17
    zac
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    [QUOTE=Buster Groove]
    Quote Originally Posted by C-40
    Personally, I never use a torque wrench on small bolts because most are holding items that get adjusted on the road. You can't take that torque wrench with you.
    QUOTE]

    I always assumed that I could return a bolt to the same torque if I retighten it the same number of turns that I loosened it. I always start with the allen wrench sticking up and then count the number of full turns that I loosen it. Then, when retightening, I simply do the reverse.

    This assumes that I can remember the number of turns after I skin my knuckles and drop the wrench a couple times. ;)
    Funny I do this too.

  18. #18
    zac
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    Quote Originally Posted by HAL9000
    Typical & similar torque settings can be used from other brands of components. try Cannondale's site. Their service PDFs contain loads of torque values as do many of the Shimano service PDFs.
    Thanks, I didn't know about Cannondales site. However, I am very aware of Shimano's tech specs on their site. It is top notch and what any technical component manufacturer should provide. (It is almost too much information, bikes used to be simple to adjust...now with STI shifters...argh.)

    Anyway that still doesn't help as I was looking for Bontrager info.

    I did notice that the 2004 Trek manuals have torque settings for the Bonty parts. You just have to read the real fine print, oh my eyes.

    I also email Trek, I will wait and see how they respond.

    Thanks all
    Zac

  19. #19
    zac
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    Quote Originally Posted by C-40
    There are some general guidelines for the common M5 and M6 bolts on bikes. 5-6Nm is generally safe for M5 bolts and 9-10Nm is safe for M6. Thes are not maximum values. Better to stay on the lower side and tighten more only if something slips.

    50Nm is common for bottom brackets and cassette lockrings.

    Most stems and seatposts come with instructions that include the recommended bolt torque. Other items, like cassette lock rings have and bottom brackets most often have the torque written on them.

    Personally, I never use a torque wrench on small bolts because most are holding items that get adjusted on the road. You can't take that torque wrench with you.

    http://www.boltdepot.com/fastener-in...ed-Torque.aspx
    Thanks. I will convert those values to lb-ins (my Nm wrench is a big boy for my jeep.) and double check what I have done.

    I really dont want to wait for slippage on my stem and bars though. I think hitting a road bump at 30mph+ going downhill only to find my bars drop...will leave me wishing that I snaped or stripped a couple of bolts and replacing a stem, than the inevitable trip to the ER with a busted collar bone or something.

    peace
    zac

  20. #20

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    Great link below:

    http://www.parktool.com/repair/readhowto.asp?id=88

    There's a .pdf on the same page for off-line referrence.
    Last edited by clintb; 10-27-2005 at 07:17 PM.

  21. #21

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    zinn's Roadbike Maint. book has a chart in t he appendix with rec torques for nearly every bolt. They have been w/in about 10% of every mfgr torque spec I've seen. It's a very useful table.

    Here's a table I've put together based on Zinn and mfgr specs


    Brake lever to handlebar 52-69 in-lbs
    Brake anchor bolt 69-87 in-lbs
    Brake shoe 43-61 in-lbs
    Brake pad 9-13 in-lbs
    Cable bolt 52-69 in-lbs

    BB
    Crank arm fixing bolt 305 - 435 in-lbs (35-50 NM)
    Dust cap 44-60 in-lbs
    Bottom bracket 435-608 in-lbs (50-70 NM)
    Chainring bolts 75 in-lbs

    Cassette lock ring 261-434 in-lbs (30-50 N-M)
    Freewheel body fixing bolt 305-434 in-lbs (35-50 N-M)

    FD/RD
    Wire fixing bolt 44-60 in-lbs
    FD M5 x15 Fixing bolt 44-60 in-lbs
    Rear DR attaching bolt (the one through the brake bridge) 70-86 in-lbs

    Stem
    Headset bolt 70 in-lbs
    Handlebar bolt 90 in-lbs

    Seatpost Binder bolt 50 in-lbs

  22. #22
    zac
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    Quote Originally Posted by felt35
    zinn's Roadbike Maint. book has a chart in t he appendix with rec torques for nearly every bolt. They have been w/in about 10% of every mfgr torque spec I've seen. It's a very useful table.

    Here's a table I've put together based on Zinn and mfgr specs


    Brake lever to handlebar 52-69 in-lbs
    Brake anchor bolt 69-87 in-lbs
    Brake shoe 43-61 in-lbs
    Brake pad 9-13 in-lbs
    Cable bolt 52-69 in-lbs

    BB
    Crank arm fixing bolt 305 - 435 in-lbs (35-50 NM)
    Dust cap 44-60 in-lbs
    Bottom bracket 435-608 in-lbs (50-70 NM)
    Chainring bolts 75 in-lbs

    Cassette lock ring 261-434 in-lbs (30-50 N-M)
    Freewheel body fixing bolt 305-434 in-lbs (35-50 N-M)

    FD/RD
    Wire fixing bolt 44-60 in-lbs
    FD M5 x15 Fixing bolt 44-60 in-lbs
    Rear DR attaching bolt (the one through the brake bridge) 70-86 in-lbs

    Stem
    Headset bolt 70 in-lbs
    Handlebar bolt 90 in-lbs

    Seatpost Binder bolt 50 in-lbs

    Thanks clint, thanks felt for taking time to respond and provide the values. I have bookmarked and printed this page for my toolbox.

    Thanks again
    zac

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