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stripped threads

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UK and Europe
Published
1 September 2005
Last activity
5 September 2005
Original author
davek
Posts
19
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  1. So, how do I know when to stop tightening a bolt?

    Say, for example, I was keen not to tighten a brake cable bolt to the
    point where the thread strips and I need to buy a whole new set of
    brake arms? (just a random example plucked from my imagination, you
    understand...)

    I think my problem is a worry that bolts will come loose, with
    catastrophic consequences, so I may have a tendency to over-compensate
    when tightening. But how can I tell when a bolt is /tight enough/? I've
    read enough past threads to have got the idea that a torque wrench is
    an unnecessary expense, but is there some other way I can learn when to
    stop tightening?

    (In the mean time, can someone recommend some good, cheap V-brakes?)
    :-(

    d.

  2. davek said:

    So, how do I know when to stop tightening a bolt?

    Say, for example, I was keen not to tighten a brake cable bolt to the
    point where the thread strips and I need to buy a whole new set of
    brake arms? (just a random example plucked from my imagination, you
    understand...)

    I think my problem is a worry that bolts will come loose, with
    catastrophic consequences, so I may have a tendency to over-compensate
    when tightening. But how can I tell when a bolt is /tight enough/? I've
    read enough past threads to have got the idea that a torque wrench is
    an unnecessary expense, but is there some other way I can learn when to
    stop tightening?

    (In the mean time, can someone recommend some good, cheap V-brakes?)
    :-(

    d.


    Brake cable bolts need only to be tightened to the point where the cable
    starts to flatten out or deform - any more and you risk damaging the
    cable. In general, bike bolts need tightened to the point just short of
    where you start gritting your teeth (when using the standard tools like
    Allen keys). In other words, tighten as much as you can without
    straining. Crank bolts are possibly an exception as they can do with
    some welly.

    Many bike shops will have V-brakes in the workshop just now taken off
    new bikes to fit discs. I got a decent set of Scott brakes for a tenner
    recently and the shop people might well have taken less if I'd pushed
    them a bit more.

    --
    Brian G

  3. davek said:

    So, how do I know when to stop tightening a bolt?

    Say, for example, I was keen not to tighten a brake cable bolt to the
    point where the thread strips and I need to buy a whole new set of
    brake arms? (just a random example plucked from my imagination, you
    understand...)

    BTDT (for a derailleur.) If you have a bit of mechanical nous, you get
    a tap for the next size up (if you stripped a hole) or a die the next
    size down (if you stripped a stud) and recut the thread and use the
    appropriate sized nut/bolt to rescue it. This is a lot cheaper than a
    new component. Be aware that you have to judge whether this weakens the
    component too much for safety (you are OK doing this to a derailleur
    but a front brake could be a bit more exciting)

    Quoted message said:

    I think my problem is a worry that bolts will come loose, with
    catastrophic consequences, so I may have a tendency to over-compensate
    when tightening. But how can I tell when a bolt is /tight enough/?

    Does the cable come loose? If not, then it is probably tight enough

    Quoted message said:

    I've
    read enough past threads to have got the idea that a torque wrench is
    an unnecessary expense, but is there some other way I can learn when to
    stop tightening?

    Itf the thread strips, it was too late ;-) But seriously, take it up
    finger tight using an allen key/spanner (ie as tight as you can get it
    using just one finger, not hand pressure on the tool. Then use your
    whole hand to take it to comfortably tight, where the tool doesn't
    leave a dent in your hand (probably between 1/4 to 1/2 a turn from
    there depending on the bolt). Remember what that felt like. If it comes
    loose then add a smidgin more next time.

    Quoted message said:

    (In the mean time, can someone recommend some good, cheap V-brakes?)

    Deore work for me. It might be a bit interesting tapping an M6 thread
    into the brake arms as there won't be much material left, though you
    might be able to use a small helicoil.

    ...d

  4. Quoted message said:

    read enough past threads to have got the idea that a torque wrench is
    an unnecessary expense, but is there some other way I can learn when to
    stop tightening?

    Don't know what has been said before on the group about torque wrenches but
    in my experience of them, mostly DIY car mechanics, everyone I know who has
    got one seems to have gone "I never had a clue about even roughly how tight
    I should get things and I always used to overtighten"

    I think they at least give an idea of what sort of ballpark range things
    should be.

    Henry

  5. Aluminium - gentle.
    Non tempered steel - a bit of welly!
    Tempered steel (ie bottom bracket axle) loads of welly!

    Its experience in the end - they don't have torque guides for bikes!
    Well I don't think so.

  6. citizen142 said:

    Aluminium - gentle.
    Non tempered steel - a bit of welly!
    Tempered steel (ie bottom bracket axle) loads of welly!

    Its experience in the end - they don't have torque guides for bikes!
    Well I don't think so.

    Try this http://www.faqs.org/faqs/bicycles-faq/part2/section-33.html
    --
    Phil Cook looking north over the park to the "Westminster Gasworks"

  7. On Thu, 1 Sep 2005 21:59:01 +0100, "Henry" <[email hidden]>

    Quoted message said:

    I think they at least give an idea of what sort of ballpark range things
    should be.

    After real tight comes real loose ...


  8. Quoted message said:


    Quoted message said:

    I think they at least give an idea of what sort of ballpark range things
    should be.

    After real tight comes real loose ...

    Hehe been there done that :-)

    Mind you the number of bolts that have failed under proper tensioning
    regimes that I have done, OK a handful in a few hundred, makes me wonder how
    many cars there are out there with disasters just about to happen.

    Henry

  9. davek said:

    (In the mean time, can someone recommend some good, cheap V-brakes?)

    I can de-recommend some; Tektros. Their Dual Pivot road brakes are
    pretty good (Although they did use to use nuts at a time when everything
    else could be done up with an allen key!), but (And I've met others now
    with the same opinion) their V-brakes suck. In fact... they squeal, and
    frequently fail to return. Given the difference in cost between them and
    Deores is pence, there is not reason not to upgrade.

    Jon


  10. Quoted message said:

    So, how do I know when to stop tightening a bolt?

    Tighten until you strip the thread then go back a quarter turn :-)

    But seriously, spanners and allen keys are sized to make overtightening an
    uncomfortable experience i.e. the spanner for a 4mm thread is shorter than
    that for an 8mm thread making the application of large torques difficultish
    without leaving dents in your fingers and making the experience painful..
    Using correctly sized spanners rather than an adjustable wrench makes
    overtightening less likely as well as protecting the nuts and heads of the
    bolts. Equally, allan keys get longer as the key size increases.

    Some folk have a natural feel for appropriate tighness, some learn through
    experiencing stripped threads, some never learn ......

  11. Response to vernon:

    Quoted message said:
    Quoted message said:

    So, how do I know when to stop tightening a bolt?

    Tighten until you strip the thread then go back a quarter turn :-)

    AASHTA:

    http://sheldonbrown.com/tork-grip.html

    --
    Mark, UK

    "The government is merely a servant - merely a temporary servant; it
    cannot be its prerogative to determine what is right and what is wrong,
    and decide who is a patriot and who isn't."

  12. Brian G said:

    Brake cable bolts need only to be tightened to the point where the cable
    starts to flatten out or deform - any more and you risk damaging the
    cable.

    I think that explains why I get through so many brake cables... I just
    have trouble overcoming the fear that if I don't do up the bolt
    /really/ tight, one day I will pull on the brake lever and find nothing
    there...

    Quoted message said:

    Many bike shops will have V-brakes in the workshop just now taken off
    new bikes to fit discs. I got a decent set of Scott brakes for a tenner
    recently and the shop people might well have taken less if I'd pushed
    them a bit more.

    Hmm, interesting thought. Thanks. I'll have to pop in to the LBS
    tomorrow.

    d.

  13. David Martin said:

    Does the cable come loose? If not, then it is probably tight enough

    It won't come loose in the workshop, but my worry is that it will come
    loose under real-life heavy braking conditions, ie exactly when you
    don't want it to come loose... maybe I worry too much.

    Quoted message said:

    Itf the thread strips, it was too late ;-) But seriously, take it up
    finger tight using an allen key/spanner (ie as tight as you can get it
    using just one finger, not hand pressure on the tool. Then use your
    whole hand to take it to comfortably tight

    That sounds like good practical advice. Thanks.

    d.

  14. Jon Senior said:

    I can de-recommend some; Tektros.

    Funny you should say that. Guess what make the brakes are that need
    replacing...

    Hmm, Wiggle currently has Deore M510 V brakes for 9.99 - sounds OK?

    d.

  15. davek said:
    Jon Senior said:

    I can de-recommend some; Tektros.

    Funny you should say that. Guess what make the brakes are that need
    replacing...

    Hmm, Wiggle currently has Deore M510 V brakes for 9.99 - sounds OK?

    Yup. I have them on Igor and on my commuting MTB (on the rear, Deore LX
    on the front)

    Good value kit.

    ...d

  16. Well, well I live and learn! Thanks for that.

  17. citizen142 said:
    Quoted message said:

    http://www.faqs.org/faqs/bicycles-faq/part2/section-33.html


    Well, well I live and learn! Thanks for that.

    I found that list of torque settings when a workmate was having loose
    crank problems. I figured it was better than telling him to give his
    crank-bolts a "really good heave" which is what I had always done.
    --
    Phil Cook looking north over the park to the "Westminster Gasworks"

  18. On Fri, 02 Sep 2005 08:33:36 +0100, Jon Senior

    jon_AT_restlesslemon_DOT_co_DOT_uk said:

    I can de-recommend some; Tektros.

    Seconded.

    Quoted message said:

    Their Dual Pivot road brakes are
    pretty good (Although they did use to use nuts at a time when everything
    else could be done up with an allen key!), but (And I've met others now
    with the same opinion) their V-brakes suck. In fact... they squeal, and
    frequently fail to return.

    It was the squealing that *really* [censored] me off, despite trying all
    sorts of different toe-in amounts. Replaced them with Magura HS11s,
    problem solved instantly.

  19. Also sprach Jon Senior <jon_AT_restlesslemon_DOT_co_DOT_uk>:

    Quoted message said:
    davek said:

    (In the mean time, can someone recommend some good, cheap V-brakes?)

    I can de-recommend some; Tektros. Their Dual Pivot road brakes are
    pretty good (Although they did use to use nuts at a time when
    everything else could be done up with an allen key!), but (And I've
    met others now with the same opinion) their V-brakes suck. In fact...
    they squeal, and frequently fail to return. Given the difference in
    cost between them and Deores is pence, there is not reason not to
    upgrade.

    Another disrecommendation for Tektro dual-pivot rim-polishers from over
    here. When I was obliged by al-Qaeda to borrow TWFKAML's Ridgeback Genesis,
    the lack of stopping power came as something of a shock to a young lad used
    to discs... and judging by the way they flex, they appear to be made from
    cheese.

    --
    Dave Larrington - <http://www.legslarry.beerdrinkers.co.uk/>
    I am Wan, for I am pursued by the Army of Plums.

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