Why can't machines stress relieve wheels?

Discussion in 'Cycling Equipment' started by Res09c5t, Jan 22, 2003.

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  1. Res09c5t

    Res09c5t Guest

    Hi, I'm curious about something. The main criticism of machine built wheels seems to be that they
    aren't properly stress-relieved. This seems like it would be fairly easy to automate. Why isn't it?
    It is just cheapness or is there something about the process that makes it more difficult? Thanks!
     
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  2. Alan

    Alan Guest

    Jobst,
    >
    > You don't need to detect windup if you don't have any, but the spoke machine people, both Holland
    > Mechanics and BMD, don't want to talk about it.
    >
    Isn't that the truth? Why fix it if it's not broken. Maybe in the end, the extra effort is just not
    worth it. If the wheels these machines are targetted at a market that don't expect the wheels to
    last 10,000 miles, then why build them to that spec? How about the Mavic Kysriums and other
    pre-built wheels? Are they machine built? How do they stress relieve and deal with spoke windup?
    Some of these wheels use bladed spokes, surely that must be a nightmare.

    >
    > By a radial pneumatic piston pressing on the rim to unload the spoke being adjusted gets rid of
    > thread torque along with spoke twist.
    >
    Won't you still need to have a method of holding the spoke? Even if the threads are greased, there
    must still be a measurable amount of friction between the nipple and the threads. I know when
    building my own wheels that no matter what I do, I still get spoke windup even if I do the
    prescribed method of turning and backing off the nipple. I would really need something to hold the
    spoke in place.

    >
    > As for stress relieving, there are two problems, the obvious one is to relieve peak stresses in
    > spokes but the other is to improve the spoke line so that 'outbound' spokes lie against the flange
    > on their way to the rim.
    >
    That's the other thing I notice when building some of my wheels is that in order for me to have the
    'outbound' spoke lie against the flange of the hub, I would have to put quite a 'bow' in the spoke.
    I bend the spoke one by one so that initially they lie against the flange but as I tighten up the
    wheel, they naturally straighten out and don't necessarily stay flat against the flange and I try to
    improve the spoke line as I tighten the wheel. I don't have any problems with my wheels but that's
    not to say they're perfect.

    Alan
     
  3. Jobst Brandt

    Jobst Brandt Guest

    Alan who? writes:

    >> You don't need to detect windup if you don't have any, but the spoke machine people, both Holland
    >> Mechanics and BMD, don't want to talk about it.

    > Isn't that the truth? Why fix it if it's not broken. Maybe in the end, the extra effort is just
    > not worth it. If the wheels these machines are targetted at a market that don't expect the wheels
    > to last 10,000 miles, then why build them to that spec? How about the Mavic Kysriums and other
    > pre-built wheels? Are they machine built? How do they stress relieve and deal with spoke windup?
    > Some of these wheels use bladed spokes, surely that must be a nightmare.

    Wheels of all price ranges should be machine built, if not today, some time in the future when
    someone realizes there is a large unmet market. The bicycle business is not a fast learner as you
    see especially in wheels. Just consider that until the printing of "the Bicycle Wheel" the cause for
    spoke and rim failure was not known, nor was the concept that the spokes of wheels standing on the
    shelf have more stress in them than in a wheel being ridden. This stuff has been hanging around for
    more than 100 years and no one in the bicycle business bothered to study the prestressed wheel and
    why it is such an elegant structure.

    >> By a radial pneumatic piston pressing on the rim to unload the spoke being adjusted gets rid of
    >> thread torque along with spoke twist.

    > Won't you still need to have a method of holding the spoke? Even if the threads are greased, there
    > must still be a measurable amount of friction between the nipple and the threads. I know when
    > building my own wheels that no matter what I do, I still get spoke windup even if I do the
    > prescribed method of turning and backing off the nipple. I would really need something to hold the
    > spoke in place.

    If you can thread a spoke nipple onto a flat spoke by hand, then the machine can do it just as
    easily by unloading the spoke at the moment of adjustment. These machines have myriad are pistons
    and control sensors anyway, so it's not a significant addition although it is a significant
    improvement of throughput and precision and enables high tension to be achieved.

    >> As for stress relieving, there are two problems, the obvious one is to relieve peak stresses in
    >> spokes but the other is to improve the spoke line so that 'outbound' spokes lie against the
    >> flange on their way to the rim.

    That's no problem. There are two machines, one is used to lace the wheel and bring it to 90% of
    final tension and the aligner robot that does final tensioning and truing. Spoke line problems are
    easily addressed in the lacer and stress relieving and tension in the aligner. You'll notice that
    Holland Mechanics as well as BMD calls stress relieving "stabilizing" because they do not understand
    the concept... and therefore cannot talk about it with mere people who don't use their product.

    > That's the other thing I notice when building some of my wheels is that in order for me to have
    > the 'outbound' spoke lie against the flange of the hub, I would have to put quite a 'bow' in
    > the spoke.

    I think there is something wrong here. Improving the spoke line is something done after the wheel is
    laced and moderately tight. I don't understand your "quite a 'bow'" comment. Are you sure we are
    talking about the same thing?

    > I bend the spoke one by one so that initially they lie against the flange but as I tighten up the
    > wheel, they naturally straighten out and don't necessarily stay flat against the flange and I try
    > to improve the spoke line as I tighten the wheel. I don't have any problems with my wheels but
    > that's not to say they're perfect.

    What can I say? You seem to be unique in this experience. Either that or you are doing something
    entirely different. The second seems to be the case judging from your earlier comments.

    Jobst Brandt <[email protected]> Palo Alto CA
     
  4. Jobst Brandt

    Jobst Brandt Guest

    John McGraw writes:

    > I would sincerely like to know how 'nominally normal' person finds the strength & pain threshold
    > to straighten the in bound (I think? whichever ones have their heads on the inside) spokes w/
    > their thumbs. (per Brandt's book) All I can figure is that they must eat a couple a NY Kryptonite
    > locks a day, to keep the doctor away.

    Inbound spokes do not need this treatment because spokes are made with an obtuse angle at the elbow
    because you can't get in there with tools or hands to change it. You'll notice that the book does
    not say that these need aligning.

    > When I try this, the line is improved slightly, but not nearly enough. (Doesn't look like the pics
    > in Brandt's book.) I find Sheldon's suggestion of using an old left Nuovo Record (if mem. serves)
    > crank to apply the pressure much more realistic.

    I don't see how you think that Sheldon's stress relieving method will change spoke elbow alignment.
    As I pointed out earlier, to alter the spoke line would require the entire spoke cross section to be
    raised to yield stress, something neither rim nor hub would survive in gracefully.

    > The only problem w/ that is that it's entirely possible to over correct them. Also how does Mike
    > Jacoubowsky measure the stress releasing tension? I'm not sure it improves the wheel, but I'm not
    > sure it doesn't. I suspect enough is enough.

    In that case you'll have to take it on faith, considering how much has been written about it here
    and in the book you profess to have read.

    > When a couple of revolutions of ~80% or so, of max S.R. do not produce any change. Either Brandt's
    > way or Shraner's lateral method.

    Go back to the book and read what stress relieving does. It does not produce any visible changes in
    the wheel and that's why your expectations are not met.

    > If the wheel lasts a few thousand miles w/o adjustment, does it matter? But I not sure. What is
    > ~80%? When the wheel or my hands feel like they're going to brake if I go much further. Any
    > answers appreciated.

    Stress relieving also has no effect on wheel alignment. As I said, go back to the book that you
    allude to having and read about it before saying it doesn't work. My problem with your presentation
    is that you may influence unsuspecting readers that your line of reasoning is valid. It is not.

    Jobst Brandt <[email protected]> Palo Alto CA
     
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