landotter wrote:
> On Jan 16, 2:53 pm, [email protected] wrote:
>> Granddaughter writes:
>>>>> does anyone know for a fact whether the QBP wheels are stress
>>>>> relieved? I asked Sheldon but he is not sure. Looking for value in
>>>>> an old school wheel.
>>>> Whether it works or not, doing it again yourself won't hurt
>>>> anything.
>>>> You can squeeze all the spoke pairs together yourself in less than
>>>> five minutes, including the time to find some heavy gloves. That's
>>>> Jobst's method.
>>>> Or you can try Sheldon's method--stick a smooth crank arm into the
>>>> vee of the crossing spokes and twist 'em:
>> http://www.sheldonbrown.com/wheelbuild.html
>>
>>>> Or you can take the wheels off, set the axle on a block of wood,
>>>> put a hand on either side of the rim, and lean on it, repeating
>>>> around the clock and then on the other side. That's the Mavic
>>>> method, which uses your body weight and seems to produce higher
>>>> tension:
>> http://home.comcast.net/~carlfogel/download/SpokeTension.pdf
>>
>>> The axle and block of wood method is far superior to anything else.
>>> With factory wheels I always do this, retrue and build up the
>>> tension between 1/2 and 3/4 turn and end up with very stable
>>> wheels. Squeezing or using granny's pasta fork just doesn't pull the
>>> spokes hard enough.
>> I think you are mistaken in that method. If you put a tensiometer on
>> the wheel and try both manual spoke stretching and the method you
>> outline, you'll find they produce similar increases in spoke tension
>> except that pressing down across the diameter of the wheel deforms it
>> and puts permanent deformation into the wheel. By manually working
>> pairs of spokes that overlap each other, there is only a slight radial
>> deformation with no lateral effect.
>
> ********. The axle-on-wood method works far better than the squeeze,
> which rarely gets the spoke head seated fully in the flange. The
> "permanent deformation" claim is also ********. You just work the
> wheel till you see the spoke heads seat. You're simply lying and being
> dogmatic for your ego. How Jobstian!
It's not the increase in tension that makes the "axle on wood" method
superior. It's the decrease in tension on the under side of the wheel.
What you're essentially doing is simulating the unloading of spokes that
naturally occurs when you ride on a wheel.
On the road, as each spoke comes to the point normal to the plane of the
ground, the rim is ever so slightly deformed to unload the tension on
the spoke. Without that tension, the static friction force in the
threads that is holding the spoke against unwinding (and you have to
have spokes with wind-up in them for this to matter) is reduced, and the
spoke twists in the nipple to relieve the wind-up. This is why you hear
the "pinging" sounds if you ride on an unrelieved wheel.
There's a good discussion of this in Barnett's Manual, Volume 2, page
17-24. There's also a discussion of spoke squeezing on page 16-42 that
basically says the reason for squeezing is not to relieve spoke wind-up,
but to prevent spokes from breaking due to fatigue by introducing a
slight bend in the spokes where they cross. For this purpose, I expect
that Sheldon's method is superior.
A consequence of this latter contention is that it would do no good at
all to squeeze spokes on a radial lacing or on a wheel like the recent
Shimano rear wheels, that don't actually have the crossing spokes
touching each other.
Jobst's remark about putting a permanent deformation in the rim is total
****. Doesn't happen, unless you push hard enough to taco the wheel.
Mike Johnson
